Sciences : histoire orale

BOILOT Jean-Pierre, 2000-12-12

Sophie Jourdin — 2011-10-28T12:00:58Z

Jean-Pierre Boilot worked on b-alumina in the 1970s and subsequently on ionic conductors within the framework of chimie douce.

BERNADETTE BENSAUDE-VINCENT (BBV) : Quel fut votre parcours individuel ?

JPB : Je suis entré au laboratoire Collongues en 1971, étant assistant à l'Ecole de céramique de Sèvres où j'enseignais la chimie. Mon sujet de thèse portait sur l'alumine-b plus exactement sur les gallates. On cherchait à améliorer la conduction ionique en remplaçant l'aluminium par du gallium. On connaissait, bien sûr, les travaux de Yao et Kummer et on savait déjà échanger les ions sodium par d'autres. Mais ceci n'a constitué qu'un chapitre de ma thèse qui devait en avoir 5 ou 6.
Après j'ai eu un rôle très particulier : travailler à l'interface de la physique et de la chimie. Cette expérience de collaboration de la physique et de la chimie du solide, c'était une innovation. Seul Yves Le Car avait commencé avant moi. Lui avait un financement industriel, avec CGE qui est devenu Alcatel. Cette collaboration est issue de discussions entre Robert Collongues et André Guinier qui était responsable d'un groupe de physique du solide à Orsay au bâtiment 510. Le Car a commencé à faire de la diffusion des rayons X, organisation des ions de conduction dans alumine-b. J'ai poursuivi dans cette voie. La collaboration s'est étendue. Je passais 50% de mon temps au labo Collongues et 50% en physique chez Guinier et chez Jérôme, un autre groupe de physique du solide qui faisait de la RMN. Une grande partie de ma thèse concernait des problèmes fondamentaux : comment les ions s'organisent, ordre désordre, stœchiométrie.

BBV : Quels étaient les modèles théoriques à l'époque ?

JPB : Peu de choses pour comprendre les mécanismes de conduction. C'est venu plus tard. Les physiciens durs ont attaqué le problème plus tard.
J'ai soutenu ma thèse d'Etat en 1975 devant un jury très impressionnant : Jacques Friedel, Jean Rouxel, Michel Fayard, qui est devenu directeur du secteur chimie au CNRS, Jeanine Théry et Robert Collongues. Je me souviens avoir été mauvais, je n'étais pas fier de moi.

BBV : Avez-vous poursuivi sur alumine-b ?

JPB : Oui de 1975 à 82 j'ai travaillé avec Gaston Colin, cristallographe et avec Philippe Colomban qui est arrivé au labo Collongues. Je l'avais eu comme étudiant à l'école de céramique. On a travaillé essentiellement sur deux aspects : alumine-b stœchiométrique et alumine-b''. Même type de base : compréhension, organisation des ions en utilisant les paramètres fondamentaux du solide : répulsion entre ions, transition au désordre etc.

BBV : Y avait-il alors une communauté française de chercheurs sur l'alumine-b ?

JPB : Oui, il y avait des séminaires organisés ici à Polytechnique par Bernard Sapoval->http://pmc.polytechnique.fr/bs/english.html] et Hervé Arribart. Les gens ici ont commencé à travailler sur l'alumine-b avec des porteurs de protons et ils utilisaient la RMN.
Donc si l'on fait le bilan de ces 10 ans, il y a deux caractéristiques propres à ce sujet

- C'étaient les premières recherches fondamentales menées parallèlement à la recherche industrielle car CGE en France, Ford, General Electric aux USA faisaient des recherches plus appliquées sur les accumulateurs sodium-soufre. C'était particulièrement motivant de voir qu'il y avait des possibilités d'application.
- Deuxième caractéristique : c'était la possibilité de travaux à l'interface physique-chimie. Ces deux aspects là se retrouvent plus tard dans les recherches sur les supra-conducteurs au cours des années 90.

BBV : Aviez-vous des contacts avec l'industrie ?

JPB : On avait des contacts avec CGE et on allait parfois à Marcoussis voir M. Dumas de CGE. Mais on faisait de la recherche fondamentale.
Des contacts avec l'industrie, il y en avait sans doute au labo Collongues. Mais je n'étais pas au courant. Par contre, au laboratoire Collongues, Didier Goureyet était plus proche des préoccupations industrielles, tout en étant en recherche fondamentale.

BBV : Avez-vous ressenti un certain pessimisme industriel sur l'alumine-b au cours de ces années ?

JPB : Non, il y eut une effervescence de 1970 à 76. Le pessimisme est venu après. Il y avait peut être des problèmes pour les gens qui ne travaillaient pas sur le sujet. C'est faux de dire qu'il y avait un pessimisme dans les années 70. Pour les années 80, c'est une autre histoire. Plus de problème d'énergie, d'autres problématiques sont arrivées : utiliser des systèmes. On savait que les batteries sodium-soufre ne seraient pas commerciales. Elles ne le seront peut-être jamais. Donc du point de vue industriel, c'était un tout petit peu moins motivant.

BBV : Avez-vous participé aux congrès internationaux des années 70-80 ?

JPB : Bien sûr je pourrai vous donner la liste. C'est un autre aspect important : il y avait une compétition internationale, essentiellement avec les Américains, avec les gens de General Electric - Roth - et les gens de Bell Telephon. J'ai commencé à participer en 1976 Schenectady ; 1979 Lake Geneva (USA), Gatlinburg (Tennessee) en 1981, Grenoble en 1983, Lake Tahoe en 1985 ; Garmisch en 1987. Outre cette série des Solid State Ionics il y avait Rome (1976) et Saint-Andrews en Ecosse, en 1978. A chaque fois on avait des papiers dans ces conférences.

BBV : Y-a-t-il eu une évolution ou réorientation de vos recherches sur cette période ?

JPB : On a pousuivi les mêmes pistes de recherche sur les deux alumines-b.
Philippe Colomban, chimiste, s'est consacré à l'élaboration des mono-cristaux d'alumine-b. Seuls deux groupes au niveau international savaient faire la synthèse des alumines-b : Colomban au laboratoire Collongues et Farrington chez General Electric. C'était un procédé à haute température avec quelques subtilités chimiques pour parvenir à faire l'alumine stoechiométrique. Mais il n'y eut pas de brevets sur les mono-cristaux. L'objectif était purement fondamental car les applications se faisaient sur un milieu polycristallin, céramique.
Parallèlement à partir de 1978, on a commencé à travailler sur d'autres conducteurs ioniques qui pouvaient remplacer l'alumine. Ils faisaient partie d'une série qu'on appelait nasicons : c'étaient des phosphates ou des phospho-silicates avec des ions sodium.
Le choix du sodium repose sur des arguments très simples : il faut un ion monovalent, de la bonne taille. S'il est trop gros il ne diffuse pas facilement ; s'il est trop petit (cas du proton ou du lithium) il vient se coller sur le réseau ; ou on a une interaction trop forte avec les anions (les chimistes disent trop polarisants). Les meilleurs ions sont Na+ et Ag+. Ensuite le choix dépend des applications. A cette époque là le problème était le stockage d'énergie, on visait des accumulateurs de haute puissance pour faire du stockage. Les critères de densité d'énergie massique portaient le choix sur les éléments légers, donc le sodium plutôt que l'argent.

BBV : Est-ce que la crise d'énergie a infléchi les recherches au labo Collongues ?

JPB : Peut-être mais à cette époque j'étais trop concentré sur ma thèse et je n'avais pas de vue d'ensemble. Pour revenir aux applications, les nasicons ont eu moins d'intérêt car ils sont moins stables, ils résistent moins bien au sodium liquide. Ils n'ont pas eu le succès de l'alumine-b mais des gens travaillent encore dessus. Il y a eu beaucoup de travail sur cette famille : diversité de compositions et de phases. Elle présente un intérêt pour la compréhension des paramètres fondamentaux du solide mais moins que l'alumine-b.

BBV : Rétrospectivement considérez vous que ce travail sur les nasicons a été positif ?

JPB : Oui on aurait peut-être pu arrêter un peu plus tôt. On a travaillé là dessus de 1978 à 1984 mais toujours en parallèle avec l'alumine-b. C'est un travail qui se faisait à Polytechnique où je suis venu en 1981. C'est un sujet qu'on a développé ici avec Colomban, toujours en liaison avec les physiciens du solide (Collin) d'Orsay dans le groupe de Robert Gomès qui avait pris la succession de Guinier.
Après on a pris un virage vers les sols-gels. La transition s'est faite par le biais des nasicons. On avait dans l'idée d'élaborer des phases amorphes pour conducteurs ioniques. Elles étaient dérivées du nasicon. On a préparé les premiers verres organo-minéraux en s'inspirant des conducteurs ioniques type nasicons. Notre modèle à nous était le conducteur ionique. Puis on a eu des résultats intéressants sur ces matériaux, sans rapport avec la conduction ionique. Ces hybrides organo-minéraux, à la frontière entre organique et minéral sont faits à température ambiante avec une chimie douce.

BBV : N'est-ce pas un paradoxe que de la chimie à haute température du labo Collongues sorti une chimie à température ambiante ?

JPB : Oui à la même époque Jacques Livage faisait des gels V205.

BBV : Qu'est-ce qui a motivé votre virage vers les verres ?

JPB : Du point de vue industriel, l'alumine-b c'était moins motivant et, du point de vue fondamental, on avait fait le tour. De plus, je démarrais un groupe ici à Polytechnique, c'était le moment de passer à un nouveau projet.

BBV : Est-ce que ce virage vers les verres organo-minéraux a changé votre place dans la recherche ?

JPB : Au niveau du CNRS, non, car on appartient toujours à la famille chimie du solide. Mais on a eu des contacts industriels nouveaux avec Saint-Gobain (Silor). Bien sûr pendant deux ans, on a eu un peu de ralentissement dans la production de publications. Mais le virage se fait bien.

BBV : Quelles sont les activités de votre laboratoire actuellement ?

JPB : Actuellement on est toujours sur la chimie douce. En plus des hybrides organo-minéraux, on travaille sur des objets nanométriques. On part de molécules et on essaie de construire des solides à partir de ces molécules. Ce sont essentiellement des matériaux pour l'optique : lasers ou stockage de l'information optique.

BBV : Quelles sont les techniques que vous utilisez ? Sont-elles totalement différentes de celles qu'on utilisait au laboratoire de Collongues ?

JPB : C'est de la chimie classique avec des béchers mais pas de haute température. C'est bien différent des labos d'alumine où on avait des fours à 2000°C. Le labo Collongues était surtout tourné vers l'élaboration de matériaux alors que maintenant on fait surtout de la caractérisation. Comme maintenant on dispose de nombreuses techniques, on peut faire des thèses sur la caractérisation avec peu de chimie.
Ce que m'a appris l'alumine-b c'est qu'il faut faire de la chimie. C'est le matériau qui est intéressant. C'est le message le plus important. Toutes les avancées qu'on a eues au laboratoire Collongues, c'est parce qu'on a su faire de la synthèse de matériaux avant et mieux que les autres. Notre premier travail est de faire de l'innovation en matériaux, mais on a beaucoup de collaboration en physique.
Notre troisième thème est la pile à combustible. Il est arrivé avec un ancien du laboratoire de Collongues : Philippe Barboux. Il travaillait sur les films minces de céramique et prépare maintenant des membranes conductrices ioniques pour les piles à combustibles. C'est donc un retour à la tradition d'origine.
Mais il y a un lien entre les verres, les particules nanométriques et les piles à combustibles. Ce sont toujours des procédés à basse-température. On travaille sur la diffusion de molécules comme autrefois on travaillait sur la diffusion des ions.

BBV : Combien de personnes travaillent dans votre groupe ?

JPG : Actuellement notre groupe de chimie du solide comprend 10 personnes et il est l'une des composantes de l'UMR-CNRS intitulée Laboratoire de Physique de la matière condensée qui comprend 50 personnes.

BBV : Quels sont vos liens avec l'étranger ?

JPB : Nous avons gardé des relations avec Bruce Dunn de UCLA (nous avons ici un chercheur permanent qui a fait son post-doc là bas). Nous avons également une collaboration avec un laboratoire allemand. Pas de programme européen, c'est trop de paperasses.

BBV : Comment voyez-vous la chimie du solide française sur la scène internationale ? Est-ce qu'elle n'a pas d'une certaine manière fait obstacle à l'essor d'une science des matériaux en France ?

JPB : C'était suite au démarrage de la physique du solide. Il y a avait a deux pôles de chimie du solide en France, celle de Hagenmuller à Bordeaux et celle de Collongues à Paris. L'une plus mandarinale que l'autre. Des gens comme Rouxel, je les mets dans la famille Hagenmuller. En fait, si on prend les labos actuels de chimie du solide, ce sont tous des descendants d'Hagenmuller ou des descendants de Collongues.
Les deux écoles sont tournées vers la science fondamentale plus que vers les applications. C'est totalement différent de l'approche science des matériaux aux USA. Elle n'existe pas en France. L'approche Materials Science est plus tournée vers les applications. En France, il y a eu beaucoup de recherche fondamentale. L'originalité française n'est pas dans la collaboration avec l'industrie mais dans l'approche physique, dans la collaboration entre chimistes et physiciens du solide. Je défends l'approche française. Si les gens avaient été très proches du milieu industriel, je ne crois pas qu'on aurait été aussi forts en chimie du solide.

BBV : Peut-on associer une coloration politique à cette discipline ?

JPB : Traditionnellement en France, les physiciens sont plutôt à gauche et les chimistes plutôt à droite. Quant à la couleur de ces deux écoles de chimie du solide, je dirais que Hagenenmuller était un gaulliste bon teint ; il serait plutôt proche de Pasqua aujourd'hui ; Collongues, lui, était plutôt centre droite, bon vivant.

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Pour citer l'entretien :

« Entretien avec Jean-Pierre Boilot », par Bernadette Bensaude-Vincent, 12 décembre 2000 Sciences : histoire orale, https://sho.spip.espci.fr/spip.php?article121.

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Entretien avec Jean-Pierre Boilot, par Bernadette Bensaude-Vincent, 12 décembre 2000

Lieu : Ecole polytechnique, Palaiseau, France

Support : non communiqué

Transcription : Bernadette Bensaude-Vincent

Edition en ligne : Sophie Jourdin

FRIEDEL Jacques, 2001-10-17

Sophie Jourdin — 2011-09-19T08:25:40Z

Jacques Friedel, born in Paris, February 11, 1921, entered the Ecole polytechnique (1944-46) then the Ecole nationale supérieure des mines (1946-48). He thus followed up the family tradition starting with his great-grand father Charles Friedel, a famous organic chemist and crystallographer at Paris Sorbonne, his grand-father Georges Friedel best known for his work on liquid crystals, his father Edmond Friedel who was the director of the National School of Mines (1937-65). Jacques Friedel obtained a Licence ès sciences degree at the University of Paris in 1948, then was initiated to physical metallurgy in the Metallurgy Laboratory of the School of Mines headed by C. Crussard. He spent three years at Bristol University (UK) in Nevill F. Mott's physics department. There he became acquainted with the electronic structure of metals and with dislocations, a topic developed by Charles Frank. In 1952 he got a PhD. from Bristol and a Doctorat d'Etat in Paris in 1954 on the electronic structure of impurities in metals.
In 1956, he became assistant professor at Paris University, then full professor of Solid State Physics at Paris Sud in Orsay from 1959 to 1989. For thirty years he developed a research school in solid state physics, authored a volume Les dislocations (Paris, Gauthier Villars, 1956, 2nd ed. Dislocations, Pergamon, 1964) and more than 200 journal articles. His original contributions dealt with various branches of solid state physics, in particular the electronic structure of metallic alloys and of metals, the structure of surfaces of dislocations and of clusters.

Jacques Friedel chaired the Consultative Committee to the French Government for scientific and technological research (1978-1980), was the President of the Société française de physique and of the European Physical Society. Among many responsabilities in French scientific institutions, Jacques Friedel became the President of the French Academy of Sciences (1992-1994)

Pour citer l'entretien :

« Entretien avec Jacques Friedel », par Hervé Arribart et Bernadette Bensaude-Vincent, 17 octobre 2001, Sciences : histoire orale, https://sho.spip.espci.fr/spip.php?article80.

JACQUES FRIEDEL (JF) : Je voudrais commencer par quelques remarques générales que m'inspire votre projet.
La première concerne la notion de matériaux. Le terme et ce qu'il représente pour l'enseignement comme pour la recherche font partie d'une évolution générale des universités après la Deuxième Guerre mondiale. Il faut se rappeler, en effet, que jusqu'à cette époque et au delà, les départements universitaires étaient définis par grands secteurs - mathématiques, physique, chimie, biologie, géologie, astronomie - à l'intérieur desquels les « chaires » professorales de spécialité étaient définies, en physique du moins, par la nature de l'instrumentation employée : cristallographie (c'est-à-dire rayons X), acoustique, optique, thermodynamique, etc. En chimie, par contre, l'opposition entre minérale et organique était transcendée par le développement plus récent de la chimie physique qui, avant guerre, avait tendance à couvrir le futur domaine des matériaux. Ces subdivisions existaient aussi dans les organismes de recherche comme le CNRS. Le développement des applications pratiques de la physique nucléaire comme des grands laboratoires de recherche industriels (Philips, GECO, Bell, IBM) avaient fait éclater ces divisions et montré la nécessité de repenser l'organisation de la recherche comme de l'enseignement.

C'est dans ce contexte lors d'une réunion de l'American Physical Society que Roman Smoluchowski a le premier, je crois, proposé le développement d'instituts de recherche et la création d'une société (américaine) centrée sur l'étude des matériaux. Elle devait regrouper chimistes, physiciens, mécaniciens et aussi cristallographes et métallurgistes alors dispersés dans diverses sociétés.
Cette proposition avait une résonance évidente dans les grands laboratoires appliqués, relevant soit de l'industrie soit d'organismes d'Etat. Mais elle était trop extrême pour la recherche universitaire. Celle-ci avait commencé à se réorganiser à l'intérieur de la physique comme de la chimie, en départements distincts mais spécialisés autour des particules et des noyaux, des atomes et des molécules, et finalement des solides. Pour ces derniers Bristol, avec N.F. Mott et bien d'autres, a été un premier noyau conscient et organisé, dès avant la guerre. Mais la personnalité de F. Seitz, auteur du premier livre sur la physique de l'état solide, a joué un grand rôle, avec la création au début des années 50 de son département de physique à Urbana (Illinois). De la même époque, datent l'Institut de physique des solides de Tokyo et le groupe de physique des solides de Pierre Aigrain à l'Ecole normale supérieure (Paris). Notre laboratoire de physique des solides a été fondé à Orsay en 1959. Le Max Planck de Stuttgart (Physique et chimie des solides) et le laboratoire correspondant du centre nucléaire de Jülich (Allemagne) datent des années 1960. Enfin, en France, le développement des 3° cycles universitaires à partir de 1955 s'est fait en physique et (sauf pour la cristallographie) suivant le même découpage. Peu après, le CNRS suivait la même voie pour réorganiser ses commissions avec une section « physique des solides » remplaçant, à ma suggestion, l'électronique, la thermodynamique et l'optique des solides. Toutes ces réformes confortaient le découpage des universités comme des organismes type CNRS ou Max Planck en domaines disciplinaires de physique, chimie, mécanique etc. Ce grand découpage sera maintenu dans la réforme Fouchet de l'université française en 1968. Elle supprimait en physique quelques vieilles chaires remplacées par des enseignements plus modernes, vus d'un point de vue plus général. Cette évolution s'est poursuivie dans les années 70 avec le passage vers 1975 de physique des solides à physique de la matière condensée. En Europe, ceci a permis de regrouper dans une même division de European Physical Society les gens des solides et les gens des liquides - sans oublier les cristaux liquides et les polymères remis à l'honneur par Pierre-Gilles de Gennes et d'autres. En France, le changement de dénomination a permis aussi aux cristallographes de rentrer dans le rang au CNRS, par la création de deux sections de matière condensée, au prix d'une séparation regrettable entre aspects atomiques et aspects électroniques.
C'est donc dans ce contexte général qu'il faut juger le développement du concept de matériaux. Aux USA, la création au milieu des années 60 d'instituts universitaires des matériaux - dont seuls certains ont survécu - a été présentée et jugée comme une tentative d'introduire l'interdisciplinarité dans un milieu encore dominé par le découpage en départements de grandes disciplines et par l'individualisme des enseignants, souvent encore instables et toujours dépendants de contrats personnels de recherche.
En France, les matériaux ont émergé officiellement en 1970-71. J'étais alors le premier président physicien (et non chimiste) d'une Action Concertée en Métallurgie de la DGRST (Délégation générale à la recherche scientifique et technologique, précurseur du ministère de la recherche). Cette action, comme bien d'autres en électronique, par exemple, avait pour but de favoriser l'octroi de contrats de 3 ans, des travaux en commun de laboratoires différents, appartenant si possible à l'université et à l'industrie. Sous la poussée du vent de réformes post-1968, la commission de cette Action concertée a bâti un programme d'enseignement des matériaux, animé par mon cousin et premier patron Crussard, alors de retour d'un voyage aux Etats Unis et membre de la Commission. Ce programme, qui accordait une place prépondérante aux matériaux de structure, a été immédiatement adopté par les écoles d'ingénieurs impliquées dans ce domaine (métallurgie, plastiques, céramiques). Il y a eu aussi la création de DEA universitaires en matériaux en province comme à Paris. Le rapprochement entre physiciens et chimistes, comme les débouchés industriels ont été jugés positifs. Les cristallographes y ont souvent vu une manière de s'épanouir, de former des gens qui iraient plus facilement dans l'industrie. En se séparant en 1971, cette Action Concertée de Métallurgie a laissé un rapport émettant le vœu qu'une Action Concertée Matériaux pour la recherche lui succède, en suggérant un premier programme. Sous la direction de Pierre Aigrain, ce projet a été accepté par la DGRST. Le CNRS a suivi très rapidement en créant les premiers programmes de recherche intersectoriels, destinés à jeter des ponts entre les départements. Celui des matériaux, l'un des plus importants et des plus stables, a longtemps été dirigé par Jean Hanus.

Ce démarrage des matériaux reste relativement modeste. En France, comme aux USA, il concerne surtout l'enseignement des écoles d'ingénieurs et de certains DEA. Il se réduit bien souvent à une alliance entre métallurgistes et physicochimistes dans une perspective d'ingénieurs. L'électronique reste au départ en dehors du mouvement.
Je pense que l'importance qu'ont prise graduellement les matériaux est venue principalement de ce que c'était un terme commode pour couvrir une large gamme de recherches à la fois interdisciplinaires et débouchant sur des applications pratiques, dont on pouvait affirmer l'importance pour la société et garantir d'un mot le secteur dans les plans et les budgets. C'est incontestablement ce qui s'est produit en France comme à Bruxelles (siège de l'Union européenne) dans les années 1980. La situation a dû être similaire aux USA. Cela explique le ralliement des gens de l'électronique et des semiconducteurs à cette époque.
Ensuite le mouvement s'est affermi avec la création de la Materials Research Society (1973) dont la branche européenne, animée par des physiciens nucléaires de Strasbourg, s'est développée nettement plus tard. La réponse des sociétés de métallurgie en Europe a été de se transformer en sociétés de matériaux et de se fédérer à l'instigation des Britanniques, pour faire front à l'impulsion venue des USA. Même dans la Materials Research Society, on peut noter que des réunions plus « électroniques » alternent avec des réunions plus « atomiques » !
Pour moi, la conclusion est claire : si un minimum de connaissances communes est nécessaire pour tous les gens actifs dans les matériaux, et s'il est utile qu'ils fassent front commun pour défendre ce secteur, il est moins facile de gérer au jour le jour des recherches en commun et il faut tenir compte d'autres forces et d'autres nécessités, dans l'enseignement universitaire notamment. De ce fait je ne pense pas que la notion de matériaux ait le même sens actuellement en France et aux USA.

Deuxième remarque, l'interdisciplinarité, souvent présentée comme caractéristique de la recherche en matériaux, s'est pratiquée bien avant le développement de ce terme. Ainsi la Société française de métallurgie avait, juste après la deuxième guerre, un groupe de physique du métal, présidé par André Guinier et qui réunissait dans des discussions et des colloques tout le gratin d'alors : industriels, gens des organismes, des écoles, des universités, mais aussi des physiciens, des chimistes, des mécaniciens, des cristallographes. Pendant dix ans, entre le milieu des années 60 et 70, la même Société de métallurgie a copatronné avec le CEA (Commissariat à l'énergie atomique) et l'IRSID (Institut de recherche sidérurgique), des écoles d'été annuelles fort suivies. Ces écoles d'été menées par Y. Adda (CEA), Yves Quéré (CEA, puis Ecole polytechnique), et J. Philibert (IRSID puis Orsay) réunissaient de jeunes chercheurs et des gens confirmés des universités, des organismes et de l'industrie. Elles couvraient des thèmes généraux qui seraient maintenant jugés matériaux. A partir de 1969 des groupes dits de Monestier (l'endroit où s'est tenue l'école cet été là) ont fait périodiquement le point sur l'état des recherches dans une dizaine de domaines spécialisés (défauts ponctuels, plasticité, surfaces, etc.). Ces réunions régulières sont maintenant oubliées car elles ont été publiées chacune séparément, en français, par un éditeur différent. Ce qui fait qu'elles n'apparaissent pas comme une série homogène.
L'interdisciplinarité a été aussi renforcée par les Actions Thématiques Programmées (ATP) du CNRS, assez similaires aux Actions concertées décrites plus haut mais dans des domaines plus pointus et variables. J'ai moi-même suscité et présidé des ATP sur les surfaces et sur les agrégats, qui ont fortement développé l'interdisciplinarité de ces domaines en France.
Un dernier aspect de l'interdisciplinarité est la nécessité de collaboration entre chimistes et physiciens pour produire des matériaux et en étudier les propriétés physiques. Dans certains cas, et sans parler de l'approche « matériaux », ceci a été fait sur place, dans le même (grand) laboratoire. Ce fut le cas (peut-être pas si souvent) dans les deux grands instituts de Stuttgart et de Jülich par exemple. A Orsay, notre laboratoire de physique des solides a cherché à résoudre partiellement le problème en implantant de petites équipes de chimistes d'abord dans la production d'alliages métalliques, puis de cristaux liquides, enfin de composés organiques conducteurs. Si ces groupes ont été très utiles, il a été parfois difficile de défendre leurs membres avec succès dans leur commission CNRS respective. Les grands laboratoires de chimie des solides français ont aussi acquis une compétence utile dans certaines techniques physiques.
Une solution très différente et, je pense, de plus d'avenir, est une collaboration entre deux groupes, l'un physicien, l'autre chimiste, sur le développement et l'étude de matériaux nouveaux. C'est de cette façon que Jean Rouxel (Nantes) et Monceau (Grenoble) ont découvert le courant de Frölich des ondes de densité de charge, que Beckgaard (Copenhague) et Jérôme (Orsay) ont découvert la supraconductivité organique (à la suite des travaux d'une ATP sur les conducteurs organiques), etc.
Donc pour résumer, avec la création des DEA, des écoles d'été, les ATP les enseignements et la recherche en matériaux ont été développés en France et assez actifs. Mais ce mouvement est assez difficile à saisir car l'ensemble ne s'appelait pas science des matériaux comme aux Etats Unis.

Troisième remarque : comme les matériaux sont un peu une création américaine, une dynamique américaine, il faudrait éviter de rééditer les problèmes posés par la réduction de l'histoire de la physique du solide jusqu'aux années 50. Le groupe de spécialistes qui avait initialement travaillé à ce projet - principalement anglosaxons et quelques allemands- ont fait une sorte d'hymne un peu excessif à John Bardeen, passant sous silence la plupart des contributions européennes notamment entre les deux guerres. Dans un deuxième temps, d'autres personnes ont été consultées. Alors trop occupé et voyant l'ampleur de la tâche, j'ai refilé la demande qui m'était faite à Guinier qui a pu rétablir un minimum de corrections, sur la conduction électrique des métaux (Linde) ou le magnétisme (Néel), par exemple. Mais le résultat final reste biaisé et j'ai été frappé récemment de voir citer cet ouvrage comme une référence irréfutable. Votre projet aussi est initialement américain et internet est surtout implanté en Amérique. Vous avez donc un biais dont il faudra vous dégager.

BERNADETTE BENSAUDE-VINCENT (BBV) : Pourriez vous préciser ce qu'il en est de l'essor de la recherche en matériaux en France ?

JF : Comme je vous l'ai expliqué, il m'est difficile de vous répondre clairement. Qu'est-ce qui appartient aux recherches matériaux, aux phases condensées, aux solides ? Si on prend l'ensemble, il est considérable et je pense comparable en valeur et en quantité par chercheur à ce qui se fait dans les autres pays développés.
Si vous prenez le sens restreint d'une recherche dans un institut analogue aux instituts de recherche en matériaux américains, je vous répondrai que cela débute bien avant le mot matériaux dans quelques laboratoires industriels comme Saint Gobain, Péchiney, Thomson CSF, CGE Alcatel comme dans les organismes de recherche appliquée, en particulier à l'ONERA (Office national en recherches aéronautiques) et au CEA (Commissariat à l'énergie atomique). Le CEA a eu, dès le départ, des sections de recherche fondamentale mais aussi beaucoup d'activités science des matériaux, où il fallait fabriquer quelque chose pour quelque chose de précis dans un but donné. De même à un moindre niveau, l'IRSID pour la sidérurgie, l'ONERA pour l'aviation et l'Ecole des mines de Paris dans son centre de Corbeil puis de Sophia Antipolis, ont développé assez tôt une approche génie des matériaux, reprise par l'université de Compiègne.

BBV : Pourquoi la science des matériaux s'est-elle mieux développée en Grande Bretagne ?

JF : S'est-elle vraiment mieux développée là bas qu'en France ? Je n'en suis pas convaincu.

BBV : Oui si l'on en croit Robert Cahn.

JF : Je connais Robert Cahn depuis 1948. C'est un métallurgiste très distingué, qui a fait des travaux remarqués dès sa jeunesse sur la polygonisation des métaux écrouis. Ses fonctions d'éditeur l'ont amené au contact d'énormément de choses. Mais il a quand même des limites, comme tout le monde.

HERVE ARRIBART (HA) : Il se pose comme un fondateur de la science des matériaux.

JF : Robert Cahn a certainement contribué à développer une image positive et vivante de la recherche en matériaux. Ceci dit, il faut tenir compte de deux effets d'optique : les matériaux dont il parle dans son livre sont surtout les matériaux de structure. Il y a fort peu de choses sur les semiconducteurs et encore moins sur les supraconducteurs, assez peu aussi sur le magnétisme. On reconnaît là la dichotomie atomes/électrons qu'il est d'ailleurs difficile de maîtriser dans un domaine aussi étendu.
Robert Cahn est maintenant connu par les livres qu'il a édités sur les matériaux. Les auteurs qu'il a sollicités sont loin d'être tous britanniques. En fait, il a, comme je l'ai dit, des contacts depuis longtemps avec la France (où il a été professeur à Orsay trois ans en métallurgie) comme avec les USA et bien d'autres pays. Ses livres reflètent donc la pluralité des pays actifs dans ce domaine avec un biais bien compréhensible pour la Grande Bretagne.

HA : Et connaissez vous John Goodenough ?

JF : Depuis moins longtemps que Robert Cahn mais je l'ai pas mal vu lors de ses séjours à Bordeaux puis à Oxford. Je pense que c'est un chimiste de grande valeur, qui a des idées théoriques intéressantes tout en produisant des matériaux nouveaux.

HA : Pourquoi avez vous choisi d'aller à l'Université de Bristol ?

JF : J'explique cela dans mon discours à la Materials Research Society pour le von Hippel Award en 1988. Je développe aussi ce point dans Graine de mandarin (Odile Jacob, 1995).
J'ai commencé une recherche expérimentale chez C. Crussard au laboratoire de Métallurgie de l'Ecole des mines de Paris, en 1948. Après quelques tâtonnements où je me suis familiarisé avec les instruments, presque tous conçus par Chevenard d'Imply, Crussard m'a donné une petite plaquette d'aluminium recristallisé dont les grains avaient des joints perpendiculaires à la plaquette. J'ai mesuré la variation de l'énergie de joints en fonction des désorientations entre grains et j'ai voulu comparer avec des calculs. A part le cas des faibles désorientations, où on se ramène à un problème de dislocations, rien n'existait alors dans les livres de physique des solides. Seul Seitz considérait l'énergie d'un cristal parfait de métal alcalin. Mais rien n'existait sur les énergies de changement de phase ou sur les énergies de défauts. Je ne pouvais pas progresser dans ce domaine sans avoir compris un peu mieux les électrons dans les métaux, responsables de leur cohésion.
Crussard me présenta alors à son ami Nevill Mott, physicien du solide à Bristol lors d'un de ses nombreux voyages sur le continent. J'étais payé par le Corps des Mines pour faire de la recherche (par le décret Suquet de 1939, applicable à 10% des corps techniques de l'Etat). J'ai ainsi passé trois ans à Bristol à apprendre la physique et à faire un Ph D. Bristol était connue, outre les travaux sur les rayons cosmiques autour du futur prix Nobel Powell, pour les travaux sur la structure électronique des solides (N. Mott) et les dislocations (F. Charles Franck). Mott m'a mis sur un problème fondamental , celui des impuretés. Quand on change la nature d'un atome de métal, qu'on ajoute ou retire un atome de ce cristal, comment les électrons réagissent-ils ? J'ai été le premier à étudier les franges de diffraction ainsi produites autour de l'impureté, d'abord numériquement (à la règle à calcul) dans des études autocohérentes puis par des théorèmes généraux simples que j'ai ainsi découverts. Dans un second temps, revenu à Paris, j'ai compris avec A. Blandin, un de mes premiers thésards, que quand les effets de diffusion par les atomes étaient faibles comme dans l'aluminium, les forces interatomiques étaient additives à volume constant et pouvaient se déduire simplement de la diffusion des électrons par chaque atome pris isolément. Le détour par Bristol m'a ainsi permis de comprendre la nature des forces interatomiques dans les métaux comme l'aluminium et donc de calculer l'énergie des joints de grains.
Avec F.C. Franck j'ai appris les dislocations, un domaine alors en grande expansion. De retour en France en 1852 j'ai continué sur les deux sujets. J'ai d'abord passé une thèse française, pour pouvoir éventuellement entrer à l'Université. Je ne voulais pas réitérer les ennuis de mon grand père, directeur de l'Institut de cristallographie à Strasbourg après avoir dirigé l'Ecole des Mines de Saint-Etienne, mais barré de la Faculté des sciences parce qu'il n'avait jamais passé sa licence ! En 1956, je suis finalement entré à la Sorbonne et en 1959 André Guinier, R. Castaing et moi avons emménagé à Orsay. Pierre Gilles De Gennes nous a rejoints en 1961 et nous avons été un des premiers laboratoires associés au CNRS (le N°2) dépendant de plusieurs commissions.

HA : Quand vous avez eu un laboratoire à Orsay avez vous accueilli des chercheurs de Bristol ou d'Angleterre ?

JF : Nous avons assez vite recruté au CNRS un Ecossais, J. Campbell qui avait fait une thèse expérimentale avec N. Kurti à Oxford dans les techniques nucléaires à basses températures. Nous avons aussi recruté C. Froidevaux, un Suisse issu du Polytechnicum de Zurich, spécialisé en techniques de résonance à Berkeley après avoir lui aussi fait une thèse chez Kurti à Oxford.
Mais c'est au niveau des échanges temporaires que nous avons eu le plus de contacts avec l'étranger, dans les deux sens et la plupart avec des pays industriels. Des thésards étrangers sont venus quand nos groupes théoriques et expérimentaux ont pris de l'ampleur. Dans la vingtaine de mes propres élèves j'ai eu ainsi un Polonais, un Chilien, un Libanais, un Croate, un Allemand. Ce dernier H. Schulz, sans doute le plus brillant et le dernier de mes thésards, est malheureusement décédé récemment.
Avec l'Angleterre, j'avais des relations privilégiées avec N. Mott, devenu mon beau-frère, chez qui j'ai passé en famille de nombreux étés, surtout à Cambridge. Par lui j'ai développé des contacts avec P.B. Hirsch, S. Zimian, V. Heine. J'ai maintenu de fréquents contacts avec F.C. Franck à Bristol. F.R.N. Nabarro et R.W. Cahn ont été aussi visiteurs à Orsay.
A Bristol, où il y avait peu de thésards britanniques à l'époque, j'ai établi autant de liens avec les visiteurs étrangers, notamment des spécialistes allemands des défauts cristallins comme A. Serger, G. Leibfried, D. Kuhlmann-Wilsdorf. Enfin j'ai eu très tôt des contacts avec nombre d'Américains, dont C. Kittel, H. Brooks, W. Kohn, N. Bloemberger ont le plus compté pour mon début de carrière.

HA : Pour autant que je m'en souvienne il n'y avait pas beaucoup d'étudiants étrangers dans le DEA de physique du solide à Orsay, du moins l'année où j'y étais ?

JF : En effet on en a eu que quelques uns par an, surtout d'Europe de l'Est et des pays méditerranéens, parsemés de quelques Allemands, Hollandais, Chinois et une année deux Américains du Nord. Il n'y avait pas d'Anglais. Le DEA qu'on a créé à Orsay avec Guinier et Castaing en 1959 ne s'intégrait pas dans le cadre de formation des thèses anglaises. Leurs thèses se faisaient beaucoup plus vite en trois ans au maximum après une licence en 3 ans. Donc c'est après leur thèse que les Anglais venaient et nous nous envoyions nos propres étudiants en post-docs à l'étranger. Cette formule d'échanges de post-docs me semble de toutes façons meilleure. Il faut dire aussi que le DEA de physique des solides couvrait toute la région parisienne et que notre laboratoire recrutait (et recrute) aussi sur d'autres DEA de la région parisienne ou de province.

BBV : Votre enseignement de DEA était-il expérimental ou théorique ?

JF : Après un démarrage officieux en 1955 à Paris avec l'aide de Roman Schmolukovski nous avons eu longtemps trois cours de base, essentiellement théoriques : cristallographie, phénomènes de transport, structure générale des solides, assurés au départ par Guinier, Aigrain et moi-même. Seul Guinier avait des travaux pratiques. A partir de 1961, De Gennes a fait un cours de physique quantique. Par la suite nous avons demandé aux étudiants de faire un court stage dans un laboratoire et de rédiger et soutenir un mémoire à l'issue du stage. Mais nous n'étions pas un DEA classique, la plupart des DEA ayant la moitié de leur temps en laboratoire. Dès le début nous avons aussi développé des cours complémentaires de deuxième année beaucoup plus spécialisés et variant d'une année à l'autre. C'est ainsi que sont nés de nombreux ouvrages comme les premiers livres de De Gennes mais aussi des introductions par différents auteurs aux défauts ponctuels, à la mécanique électronique, aux ondes de spin, à la supraconductivité, le cours de G. Toulouse sur les statistiques en dimensions fractionnaires, le livre de M. Kléman Points, lignes, parois et bien d'autres.

BBV : Avez vous développé des liens avec les chimistes d'Orsay ?

JF : J'avais au départ des liens avec P. Lacombe qui dataient de l'Ecole des Mines. Je connaissais Chaudron et ses élèves, notamment Collongues et surtout Revcholevski qui collabore depuis longtemps avec Jérôme sur les supraconducteurs. Je connaissais beaucoup de gens à Vitry, particulièrement D. Gratias, dont j'ai suivi le démarrage pour sa thèse sur les structures incommensurables de surfaces et surtout sa découverte des quasicristaux. Les chimistes avaient au départ, en France, une plus longue tradition de théorie quantique et j'ai eu des contacts fructueux dans les années 60 avec plusieurs chimistes de mon âge à Orsay. Il en a été de même avec la chimie physique, initialement brillante à Orsay dans des domaines originaux comme les cristaux plastiques ou la tenue aux irradiations des molécules organiques, deux domaines dispersés par la mort ou le déménagement des acteurs, à part la réaction photographique de Mme Belloni. Quant à Henri Kagan dont on parle beaucoup ces jours-ci, je l'ai surtout connu et apprécié au Conseil de Troisième Cycle à Orsay quand je le présidais.

BBV : Et des liens avec les industriels ?

JF : Soyons clair : je suis un modeste théoricien des solides, pas un grand manitou des matériaux. Ceci dit, au laboratoire de métallurgie de Crussard j'ai eu l'occasion de rencontrer des métallurgistes industriels comme Herenguel et surtout Chevenard. Au retour de Bristol, j'ai fait systématiquement le tour des laboratoires industriels ; Péchiney à Chambéry a même cru que je venais espionner ! C'est l'époque où j'ai fait deux expériences extrêmes. Un sidérurgiste très distingué m'a demandé de visiter le centre de recherche d'un de ses groupes sur les ferrites ; il s'agissait en fait seulement de fabrication et on me suggérait d'espionner Philips, ce qui n'était pas dans mes cordes. Un jeune ingénieur italien de St Gobain (alors au Sud du Brésil) m'a spontanément invité à visiter le laboratoire et m'a parlé de recherches intéressantes qu'il avait engagées sur les centres colorés des verres trempés ; jusqu'à sa mort prématurée, j'ai ensuite reçu chaque année un cadeau, production Saint-Gobain.
Plus sérieusement, j'ai gardé deux contacts suivis mais avec des organismes de recherche appliquée : avec l'IRSID où j'ai été conseiller pendant près de 30 ans et avec le CEA où j'ai été également conseiller de 1955 jusqu'après ma retraite. E. Grison, qui m'a recruté, dirigeait la métallurgie civile de l'uranium et du plutonium (qui donnera le MOX). Mais très rapidement, j'ai débordé vers des problèmes de chimie physique et la physique de Saclay. Mon activité a été essentiellement fondamentale, au CEA comme à l'IRSID. J'y ai dirigé des thèses toujours dans des domaines fondamentaux : Y. Quéré par exemple sur les défauts d'irradiation dans les métaux, travaux sous-tendus par les questions de fragilité, gonflement, fluage sous irradiation dans les réacteurs nucléaires ; M. Kléman sur les phénomènes magnétoélastiques qui jouent un rôle majeur dans les mémoires magnétiques, en couches minces. J'ai aussi été longtemps au conseil d'administration du LEP (Laboratoire d'études de Philips en France). J'ai présidé les conseils scientifiques de Saint-Gobain et de France-Télécom, après celui du CENT (Centre national d'études en télécommunications) de Bageux sur les semiconducteurs.

BBV : Ces présidences étaient-elles honorifiques ou plutôt directives ?

JF : Comme toujours c'était ni blanc ni noir. Le CNET Bagneux puis France Télécom sont de bons exemples. Les créateurs du CNET Bagneux, M. Bernard et J. Serphagnon, avaient le souci que le laboratoire garde une excellence fondamentale tout en s'ouvrant largement sur la recherche appliquée. Présidant alors la Commission de physique des solides du CNRS, j'ai facilité la création d'un laboratoire associé CNET/CNRS dont j'ai présidé le Conseil scientifique durant plusieurs années. Ces réunions annuelles obligeaient les gens de laboratoire à rendre compte et les dirigeants du CNET à prendre position sur le développement du laboratoire. Avec l'adjonction d'une section venant purement des applications, puis d'un groupe propre du CNRS, l'ensemble était, lors de la création de France-Télécom l'un des meilleurs laboratoires de semiconducteurs hors silicium en Europe (composés II-V et organiques essentiellement).
J'ai quitté le CNET-Bagneux pour devenir le premier président du Conseil scientifique de France Télécom. Là les problèmes étaient d'un tout autre ordre, techniques d'abord, puis rapidement économiques et politiques. Dans un premier temps, quand France Télécom était nationalisé, nous avons de nouveau obligé les gens à présenter leurs problèmes et leurs solutions et nous avons œuvré pour l'ouverture de France Télécom à la recherche française extérieure. Le temps de la privatisation, avec le développement d'Internet et du portable, a conduit à l'abandon des grands secteurs de la recherche - y compris au Centre de Bagneux - et à la mise en sommeil de réflexions à long terme sur les nouveaux matériaux (organiques en particulier) comme sur les réseaux. Nous avons éclairé, dans notre mesure, sur les dangers tant immédiats qu'à long terme et cherché à éviter que France Télécom se referme sur elle-même au point de vue recherche.

HA : Vous avez mentionné les deux orientations de vos recherches vers l'électronique des métaux et les dislocations. J'ai le sentiment qu'à un moment vous avez favorisé le premier et un peu abandonné le second.

JF : Depuis Bristol, j'ai toujours eu une activité de recherche sur l'électronique des solides. J'ai essayé de développer des modèles approximatifs mais simples, compréhensibles et même utilisables par des non-spécialistes. Je suis un vrai élève de N. F. Mott en ce que, dans un domaine complexe où 1024 particules sont en interactions fortes, des caricatures faites sur un dos d'enveloppe me semblent pouvoir être plus pertinentes que des collections de papillons, photos léchées à l'ordinateur mais souvent peu généralisables. Après de nombreuses études sur les alliages métalliques développées avec mes thésards, je me suis intéressé à la cohésion et au magnétisme des métaux purs, dont les électrons de valence sp, d ou f sont progressivement localisés et demandent des approximations différentes. Je me suis aussi intéressé aux covalents sp qui gardent, avec l'ordre local, une bande interdite de covalence même dans l'état amorphe. Plus récemment je me suis intéressé à la physique, très riche, des surfaces et des agrégats, sans oublier des sujets à la mode comme les supraconducteurs ou les quasicristaux.
J'ai abandonné pour un temps les dislocations après la seconde édition de mon livre (1964) sous la pression des événements et puis parce que j'avais le sentiment de n'avoir plus trop à dire sur le sujet, du fait notamment que je n'avais pas développé de groupe expérimental à Orsay sur ce sujet. Mais j'y suis revenu avec les cristaux liquides. De Gennes avait été persuadé par G. Durand, rentrant de Harvard, de l'intérêt de ce domaine mésoscopique justiciable de méthodes d'analyse analogues à la méthode qu'il avait utilisée pour les supraconducteurs. De Gennes s'est penché sur l'étude des dislocations de ces corps. Mais c'est plutôt Maurice Kléman (laboratoire de Physique des solides d'Orsay, puis laboratoire de minéralogie et cristallographie de Jussieu) qui a développé ce domaine en liaison avec F.C. Franck. Je me suis remis à ce sujet, notamment aux possibilités de dislocations de rotation caractéristiques de certaines de ces phases. Les réseaux plus ou moins réguliers de telles dislocations posent des problèmes topologiques intéressants, mis en jeu dans certaines phases mésomorphes dites cholestériques (germes, phases bleues) mais aussi dans les quasicristaux. J'ai gardé le contact puisque cette année j'ai rédigé des préfaces substantielles pour deux gros livres sur la dislocation dans les cristaux liquides. J'ai fait aussi un commentaire introductif à un gros bouquin sur l'écrouissage des métaux qui reste toujours un problème ouvert.

HA : Vous avez évoqué les supraconducteurs à propos de De Gennes. Comment avez vous vécu l'arrivée des cuprates et l'excitation sur les supraconducteurs ?

JF : Les Français auraient dû découvrir les supraconducteurs cuprates si les chimistes des cuprates avaient accueilli des physiciens. C'est un beau contre-exemple de l'interdisciplinarité.
J'étais intéressé par les supraconducteurs organiques. Il y a pas mal d'analogies avec les cuprates car ce sont des structures anisotropes faites de chaînes ou de plans d'atomes parallèles ou faiblement liés. Donc d'un certain point de vue les oxydes m'ont attiré toute de suite un peu comme une extension des organiques de Jérôme (J. Denis Jérôme, laboratoire de Physique des solides d'Orsay). Mais je m'intéressais aux oxydes dans un esprit assez conservateur. Au lieu d'aller vers des choses nouvelles et compliquées, je préférais voir si une approche BCS classique ne pouvait pas marcher. Je pensais notamment que les corrélations électroniques dont B. Schrieffer, M. Rice et P.A. Anderson faisaient tout un plat, existaient certainement mais peut-être pas de façon plus notable que dans les métaux de transition comme le nickel ou le chrome que j'avais précédemment étudiés. Je ne crois donc pas aux constructions magnifiques de Phil Anderson pour les oxydes. Mais ma position est controversée : on m'a demandé près de 100 tirés-à part d'un article de revue écrit l'année de ma retraite ; mais on ne me cite jamais ! D'une façon plus générale, je pense que trop de gens se sont lancés dans une quête sans espoir d'un second Nobel après Müller.

BBV : Et comment voyez vous le futur des supraconducteurs ?

JF : Il n'y a pas encore d'applications industrielles mirobolantes. Il faudra du temps ! Mais les supraconducteurs ont deux apports quasi certains :

ils permettront peut-être de petits montages dans des systèmes électroniques de faibles puissances. De ce point de vue les gens de la Bell (Batlog, Scön) ont montré récemment une voie certes difficile à mettre en œuvre mais très intéressante.
ils ouvrent la voie à des méthodes qu'on pourrait utiliser en d'autres domaines. Par exemple, Fischer à Genève fabrique des couches atome par atome. L'idée est de faire des composés à la demande avec des structures choisies, des composés qui n'existent pas à l'état naturel, tout à fait en dehors des équilibres thermodynamiques. Par le choix de ionocovalents qui ont une interdiffusion atomique faible, les interfaces chimiques entre couches gardent leur netteté.

HA : Quelle fut d'après vous la démarche de Müller à Zurich ?

JF : Müller était un spécialiste très connu des ferroélectriques. Il est allé à une école d'été à Cargèse où des théoriciens de Grenoble ont évoqué la possibilité pour des ferroélectriques de devenir supraconducteurs. A son retour, il a cherché lesquels conduisent l'électricité et il a obtenu une supraconductivité à assez haute température. Le tort de Müller a été de s'accrocher à l'idée de ferroélectriques à laquelle personne ne croit plus guère.

BBV : Pensez vous qu'il y a un lien historique ou logique entre la supraconductivité et la conductivité ionique qu'on a appelée pendant un temps superconductivité ionique ?

JF : Il n'y a aucun lien. L'analogie des noms est trompeuse. La conductivité ionique est un phénomène atomique classique, alors que la supraconductivité est de nature quantique et électronique (malgré Müller).
Par contre, les superfluides, ou liquides quantiques ont un lien avec les supraconducteurs, rendu possible par la légèreté des atomes mis en jeu.

HA : Quelle est votre attitude à l'égard des instruments en général et des grands instruments en particulier ?

JF : Je suis un pur théoricien mais, comme De Gennes, j'aime être entouré d'expérimentateurs. A Orsay, où De Gennes nous a rejoints en 1961, on a recruté des expérimentateurs pou compléter les groupes déjà existants de A Guinier et R. Castaing. C'était difficile car il y avait en France peu d'expérimentateurs qualifiés en structure électronique des solides, surtout des métaux. Les premiers ont été J. P. Burger, puis Etienne Guyon et C. Froidevaux, un Suisse que nous avons attiré par un poste de professeur d'échange et Campbell, un Ecossais invité par le CNRS. De toute façon il s'agissait d'expériences avec de petits instruments.

Quand j'étais conseiller de la DRME (Direction de la recherche militaire et des études) j'ai facilité l'équipement de nombreux laboratoires, notamment en province, couplés à des programmes de recherche fondamentale. Il s'agissait de ce qu'on a appelé plus tard les « instruments mi-lourds », basses températures, microscopie électronique, appareils de résonance... C'était d'une certaine façon prendre le relais des contrats militaires américains qui ont aidé beaucoup de mes collègues à démarrer la recherche fondamentale après la guerre.
Quant aux grands instruments, j'ai toujours pensé que, comme la langue d'Esope, tout dépendait de la façon de s'en servir. Collectionner des spectres de phonons ou de neutrons pour un composé ou un autre, n'a pour moi guère d'intérêt et prend beaucoup de temps. Mais le programme de l'Institut Laue-Langevin (ILL) à Grenoble ne fait heureusement guère de place à ce genre d'activités. J'ai toujours pensé que ces grands instruments peuvent offrir des possibilités absolument inédites pour la physique, la chimie, la biologie en général et pour les matériaux en particulier. J'ai donc travaillé dans ce sens en plusieurs occasions.
A Orsay, par exemple, j'ai suscité la réunion de physiciens des particules et de physiciens des solides qui a permis d'ouvrir l'accélérateur nucléaire au rayonnement synchrotron, c'est à dire à la naissance de LURE (Laboratoire d'Utilisation du Rayonnement Electromagnétique). Sous la pression du radiobiologiste V. Luzzati, que j'avais connu au Conseil scientifique de l'ILL, et de mon jeune collègue Y. Farge de notre laboratoire, j'ai convaincu mon ami Laguarrigue, directeur de l'accélérateur linéaire, de tenter cette expérience. J'en ai suivi les premiers pas.
En 2000 je suis intervenu auprès du gouvernement pour le faire revenir sur sa décision d'annuler le projet SOLEIL, successeur de LURE. Cette démarche avait trois raisons :

Il faut quelques très grands instruments (comme l'ESRF de Grenoble pour le rayonnement synchrotron) fonctionnant à l'échelle européenne. Leur fonction est de découvrir des techniques nouvelles en physique et en chimie ce qui est rendu possible par les propriétés spécifiques (polarisation, cohérence, hachage temporel) et par l'accroissement de la puissance et la définition de ce rayonnement comparé aux sources classiques ou aux lasers. Mais un tel équipement est trop vite saturé pour répondre aux besoins à l'échelle nationale, où il faut former des chercheurs et appliquer ces techniques, dans des expériences souvent longues. Tout cela coûte de l'argent mais si l'on considère le nombre de personnes engagées dans ces expériences ce n'est pas exorbitant.
Le synchrotron est aussi utile aux études biologiques. Il y a là un domaine en plein développement où le synchrotron n'est pas actuellement remplaçable, notamment pour l'étude structurale de molécules complexes. On peut noter qu'il y a là une extension nécessaire de la notion de matériaux : par exemple, les techniques de croissance des cristaux de molécules à longues chaines posent des problèmes spécifiques qui devraient être analysés en priorité et où la participation de physiciens et de chimistes est indispensable.
Enfin ces grosses machines sont aussi des lieux de rassemblement interdisciplinaire...du moins si on s'y prend bien. Il ne suffit pas d'installer des machines pour générer de la collaboration.

BBV : Quelle fut votre attitude à l'égard de la politique française sur les matériaux ?

JF : Je regrette que le gouvernement ait abandonné pour la recherche son affichage d'une priorité matériaux. Je suis convaincu que c'est un secteur essentiel de la recherche où le fondamental et les applications, les universités, l'industrie et les organismes de recherche appliquée peuvent et doivent se rencontrer sur un pied d'égalité. L'idée que l'on puisse développer les sciences de l'information ou les sciences de la vie sans une solide base matériaux est une idée de pays sous-développé !
Il me semble aussi clair que le domaine général des matériaux est en évolution rapide, avec une importance croissante des secteurs matériaux organiques, composites à l'échelle atomique, importance croissante aussi du mésoscopique. Tout pays qui ignorera les problèmes de « hard » en ne privilégiant que le « soft » ou le « bio » perdra à la longue dans la compétition.
Je suis aussi pour l'interdisciplinarité qui sous-tend la recherche en matériaux. De ce point de vue que l'on ait développé ce facteur dans les maitrises universitaires, que l'on ait créé aussi des enseignements d'écoles d'ingénieurs et des DEA spécifiquement matériaux me semble une bonne chose, comme aussi la réussite de certains instituts CNRS-universités ou CNRS-industrie de matériaux.
Mais ce n'est pas la panacée : le secteur est tellement énorme qu'il faut forcément se spécialiser. Je crois au travail en commun de chercheurs formés de différentes façons ; je crois aux échanges de chercheurs, aux collaborations. Mais ceci n'implique pas pour tout le monde l'abandon des grandes divisions de spécialistes, que ce soit à l'Université ou au CNRS. Je regrette pareillement l'abandon de laboratoires fortement affichés dans certaines branches de la physique et de la chimie.
Enfin je pense que, particulièrement dans le secteur des matériaux, le développement instrumental - des microscopes atomiques au rayonnement synchrotron - a joué un rôle majeur dans les développements récents. Et rien ne permet de dire que cette dynamique très interdisciplinaire, va se tarir.

Fin de l'enregistrement

Chère Madame Bensaude-Vincent,

J'ai lu avec attention et intérêt votre analyse sur « Materials Science in the United States ». Je pense que vous avez fait un effort de synthèse remarquable sur un sujet aussi diffus et la lecture de votre texte avant notre interview aurait peut-être permis de mieux polariser notre discussion.

J'ai quelques remarques générales : le titre comporte « sciences » mais le texte parle autant (dans la 2° moitié) d'« engineering ». D'autre part le texte déborde largement des US.

Je pense que la « dynamique »matériaux s'est développée aux US par suite d'un manque d'instituts ou de grands laboratoires de recherche universitaire en dehors des domaines à grands instruments comme le nucléaire, les hautes énergies, le spatial.... La situation est un peu similaire en GB (à part des centres peu nombreux comme Cambridge, Oxford, Bristol...), mais différente en Allemagne (avec les Max Planck), en France : à partir des années 40 (LP CNRS ) et surtout 60 (LA CNRS).

Il y a d'autre part certains manques. Vous ne parlez pas des cristallographes qui, en GB, en Allemagne et en France mais aussi aux USA, ont joué un rôle pionnier dans l'étude des cristaux, des défauts cristallins, des amorphes, des changements de phase comme dans le développement des instruments (neutrons aux USA), électrons en GB, rayonnement synchrotron (en Italie puis aux USA et en France...).

La césure entre matériaux de structure et matériaux électroniques, très dommageable aux deux, particulièrement forte aux USA n'est que notée au passage. Enfin des domaines certes très européens au départ comme les agrégats et les quasicristaux manquent un peu.

Une étude aurait pu être faite sur l'analyse des relaxations plastiques en front de fissure. Celle-ci avait, avant le développement des dislocations, pris un virage très fondamental, barré avec les accidents des Comets par l'urgence de trouver des parades pratiques. On est revenu aux analyses macroscopiques, avec des paramètres tirés de l'expérience mais qui varient avec les conditions de fracture. Ce n'est qu'assez récemment, avec des gens comme Pinault à l'Ecole des mines – Corbeil, qu'on est revenu à des analyses plus microscopiques et physicochimiques. Cet aller-retour est, je pense, typique de bien des domaines. Il souligne une difficulté fondamentale de traiter un domaine comme un tout. C'est le dialogue qui doit être perpétuel entre les progrès fondamentaux et les applications. Sauf cas très rares, je ne crois pas qu'un seul institut des matériaux, universitaire ou industriel, ait créé de toutes pièces et en allant jusqu'à l'application une seule découverte utile.

Enfin sous cette pression US notamment, c'est le soutien de toute recherche dans le « hard » qui a été compris comme « materials », en opposition avec le « soft » et le « bio ». Ces dernières années, ce sont ces deux autres domaines qui ont eu la suprématie. Mais je ne pense pas la situation viable très longtemps.

Bien cordialement

Jacques Friedel

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Entretien avec Jacques Friedel, par Hervé Arribart et Bernadette Bensaude-Vincent, 17 octobre 2001.

Lieu : Académie des Sciences, France.

Support : enregistrement sur cassette.

Transcription : Bernadette Bensaude-Vincent

Hervé Arribart.

Édition en ligne : Sophie Jourdin.

ARRIBART Hervé, 2001-02-19, 05-29, 02-20

Sophie Jourdin — 2011-06-16T07:31:17Z

Hervé Arribart is the Scientific Director of Saint-Gobain Recherche, an international company of French origin with an emphasis on glass manufacture. He took his PhD from the Ecole Polytechnique in Paris in the mid-1970s and subsequently researched ionic transport using nuclear magnetic resonance. In the late 1970s he worked with Jean Rouxel's group at the University of Nantes. In 1981 he joined the company Elf to work in research and development. In 1985 he moved to Saint-Gobain, where at first a large portion of his research was closely related to the practical problems of production. In 1990 he started a laboratory (a joint venture of Saint-Gobain and the CNRS) on the basic science of glass surfaces, using a diverse set of tools and especially the Atomic Force Microscope. In 1999 he moved to the more managerial position of Scientific Director. Hervé is also on the staff of this project.

2001-02-19 :

HERVE ARRIBART (HA) : I studied at the École Polytechnique in Paris. The selection to the school is done mainly on mathematics. But during my studies I learnt to appreciate physics in particular. I decided to pursue research in solid-state physics. It was a good place to study physics. While in my last year as an undergraduate I did a Diplome d'Étude Approfondie in parallel (an intermediary between an M.Sc. and a PhD typically done for a year before starting one's PhD studies). In Orsay, near the École Polytechnique, there is a very famous place in solid state physics, a lab started by Jacques Friedel - a great name in solid-state physics. I followed this course and afterwards I did the PhD at the École Polytechnique in the field of condensed matter physics. In principle I ought to have started with a topic distant from materials science. I extracted spin-polarized electrons from semiconductors. This was in 1974.

ARNE HESSENBRUCH (AH) : How did one extract spin-polarized electrons in 1974 ?

HA : It is true of all solids, but in semiconductors it is especially interesting that when light falls upon a surface there is a coupling between the spin of photons (in classical physics : the polarization of light) and the spin of electrons. Electrons in the upper layer absorb light photons depending upon the spin. If by some technique you can extract electrons from the conduction band of the semiconductor, you can find ways to select electrons of specific spins. This was quite important at the time because at big-science institutions such as LEP [Large Electron Positron collider] or SLAC [Stanford Linear Accelerator Center], there was a need for spin-polarized electrons. And of course you then needed solid-state physics to do it. But the man who in principle was my supervisor decided to do something else. His name is Claude Weisbuch, and he is now a good friend of mine. For a few years he was the scientific director of the French Department of Defense. He is still working in solid-state physics, in the optics of semiconductors. But he decided to do something else and Bernard Sapoval, another professor at the lab, proposed that I work on new materials. At that time there was little contact between solid-state physics and solid-state chemistry. The idea was to link up with chemists. This is why very early on in my career I had contact with chemists. We worked with Parisian solid state chemists on a new material. We found a new way to draw single crystals of an already existing material. It was very nice because we could examine transport and NMR phenomena. And the material, a copper vanadium sulfide exhibited astonishing properties : a large spread of conductivity that one can measure in a standard experiment. We suspected that this was due to mixed conduction properties. Mixed conductivity refers to conductivity by both electrons and ions. The experiment appeared to verify our a priori suspicion. This gave me the possibility to present a model for mixed conduction in this material and to understand the influence of ion transport and electron transport. I also used NMR in order to understand which ions moved. It turned out that the copper ions moved. So, this was the subject of my first thesis. At the time, in France, there were two theses. The first one was called "thèse de troisième cycle". The second was the "Docteur es sciences". This degree does not exist any longer. The thesis that is done now is shorter.

I decided to continue to work with chemists. I decided to combine NMR and transport measurements. I changed my collaborators, turning to two different groups. In my PhD there had been two chapters on NMR. But I wanted to study proton transport. I had two reasons. One was that protons give a strong NMR signal. The second reason was that two reasons had been given for proton transport. In one, protons move in individual jumps. In the other the proton is a part of a more complex molecule such as the ammonium ion (NH4+) or hydroxonium (H30+). In the former case we can see the transport phenomenon as a result of molecule rotation and proton jump. The molecule would turn and the proton jumps to the neighboring molecule, which again turns and so on. This was called the rotation-jump model. The second model was for the whole complex ion to jump. This was called the vehicle model because the whole molecule acts as a vehicle. So I worked with one group of chemists in Nantes, at the Institut de Matériaux de l'Université de Nantes. It had just been created by Jean Rouxel, a chemist. With them I worked on a substance called antimony acid - a solid. I was able to show using NMR that transport occurred in this case with rotation-jump. Protons used H30+ as a complex rotator. I was also able to show that the jump was due to quantum mechanics within a certain temperature range. It was not the usual ion transport of classical mechanics.

AH : A tunneling effect ?

HA : Yes, this is one aspect of protons, because protons are very light ions allowing for this quantum effect. The other material I studied was ammonium beta alumina. This was the standard beta aluminium in which the sodium had been ion exchanged with ammonium. This material was very interesting from the perspective of NMR. All kinds of ionic motion took place at different temperatures. At the lowest temperatures, that of liquid helium (1-4K), there was rotational quantum motion. As the temperature increases the motion becomes classical.

AH : If I may make a comparison with Stanley Whittingham here. You were working on some of the same materials, you were using some of the same tools (NMR), but you were asking very different questions, right ?

HA : Yes, that is true. I was not at all involved in the application. For two reasons : French chemists were interested in materials and did not look to the application. And chemists were between me and the application, so I had no contact with attitudes such as Whittingham's. I was very happy working on the solid-state physics problems.

AH : And we are talking about the late 1970s now ?

HA : Yes, I began the proton transport research, I think, in 1976.

AH : And it went on for how long ?

HA : For five or six years.

AH : And you lived in Nantes ?

HA : No, I remained in Paris while collaborating with the Nantes group.

AH : Were you employed in Nantes ?

HA : No, not at all. At the beginning I was employed at the Ecole Polytechnique as a research assistant, and then I was hired by the CNRS - in 1977.

AH : So, the CNRS paid your salary, you were able to do basically whatever you wanted, and you collaborated with Jean Rouxel and coworkers because you found it interesting ?

HA : Yes. It was a chance to work with an outstanding chemist. French chemists were really very good. The problem, as we just said, was that there was little interest in application.

AH : What did you do next ?

HA : After my PhD thesis, I found it interesting to go to industry.

AH : I imagine that there were many advantages and disadvantages to leaving academia for industry. For instance, where was status greater, what paid better, where were working conditions better ?

HA : First of all, it was rare, even more so than today, for CNRS people, or people within the public system, to go to industry. I cannot give you a clear answer about my motivation - it was not even clear to myself at the time. I did get a higher salary in industry. I also had personal reasons for leaving Paris and going to the Elf company. I went to an Elf research lab in the Southwest of France, in a very nice place in the Pyrénées. I had small children at the time and it was much better for them to grow up in the countryside and in a very nice climate. I was also curious. So the decision involved many elements. And anyway, it was not irreversible. The CNRS allowed me to take a three-year leave after which I could have gone back. With regard to the working conditions : I was of course less free than I had been at the CNRS, but I found it more stimulating because there were a lot of different problems on the horizon, arriving almost every day. We could easily get the necessary equipment at the CNRS and at Elf, so there were no differences there.

AH : The restrictions at Elf had to do with what you were allowed to study ?

HA : Yes.

AH : What did Elf want you to do ?

HA : In principle I was hired to work on solid-state sensors. Because it was not in the direct line of my previous work I proposed that I work on solid-state sensors and ion conduction. We developed a family of sensors named ISFETs (Ion Sensitive Field Effect Transistors). It was a new kind of transistor at the time but now it is very common. You control the electrode using field effects, opening and closing the circuit between the two other electrodes. This is the way the transistor works. My idea - not an original one - was to replace this way of controlling the electrode, the gate, to replace it with a membrane, selective to such and such an ion. If you put the device in a solution containing the ion for which you have designed the system, the membrane will be charged. This charge will change the state of the solid-state transistor. It worked all right for protons. We could use the device to measure pH and afterwards we just had to change the nature of the membrane, choosing a different solid electrolyte, such as calcium fluoride.

AH : Your toolkit remained the same and you still used NMR ?

HA : Not NMR, but yes. You need large samples in order to do NMR. So it was mainly electrochemistry and surface analysis. This was between 1982 and 1985. But as I told you, in industry new projects can arrive almost every day. I had developed some skills in electronics using instrumentation at the École Polytechnique. Elf applied for a patent for a medical analysis system, a small instrument to be sold to private practitioners, as opposed to hospitals. This had nothing to do with solid-state ionics. But the people working on this project needed someone who knew about electronics, and so I got progressively more involved. After one or two years it had become my main project. This worked very well. I was very proud to design an electronic system that required no manual setting. It was set in the factory forever. This was a critical issue, because we thought that doctors could not be expected to deal with electronics - and I am sure that we were right in this. So there was nothing to check or calibrate - the system was self-calibrating. So it worked very well, and after only two or three years Elf built a plant and people were hired. But in 1984 and 1985 there were big changes in chemistry. And there was a great redistribution of all chemical industries. And Elf, that had been an oil company, in this period expanded to become also a chemical company. As a result a lot of the more diversified lines of business lost in importance. Many projects like ours were discontinued. But because we were already quite advanced we found a way to keep going. In fact it was Dupont de Nemours that found that our system was complimentary to some of theirs. The result was that Elf shipped the patent and everything else to Dupont. For a few months I considered following the project to Dupont and to the United States. In the end I decided against. I still wanted to work in solid-state physics and not to work completely in the instrument making business. But for one or two years I continued as a consultant.

2000-05-29 :

HA : For both personal and professional reasons, I decided to stay in Paris, and then Saint-Gobain offered me a position, working in a new research field : polymer adhesion on glass and other materials. It was a new topic for me too. At the time adhesion was not even considered a science. It was before Pierre-Gilles de Gennes's Nobel Prize in polymer adhesion [1991]. It was rather considered an art. Even though I had no background in the field I was interested. What interested me in the Saint-Gobain proposal was that real breakthroughs were to be expected in the science of adhesion when two materials are brought into contact. In fact this was my first real industrial experience. Of course CNRS had not been an industrial experience at all, and even at Elf I was always in the research lab. As I explained, my work at Elf had nothing to do with the industrial activities. I never visited factories. At Saint-Gobain I had to do this, at least in the beginning.

AH : Did you not say that your development of the medical analysis system resulted in the setting up of a plant ?

HA : Yes. I did participate in the design of the plan, in order to make it efficient. But I had no role in the plant itself after construction. It was also a small plant for high-tech activity.

AH : You had nothing to do with the fabrication side of it, situated in the plant – merely the R&D before the plant became functional ?

HA : Yes, exactly. Saint-Gobain of course has many plants all over France and Europe, and even the United States. But at that time, the company was still franco-français [French through and through] in its general spirit and culture, despite the many factories in other countries. There were only French directors and the system was based on the French system of education. There is a hierarchy from the École Polytechnique through the École des Mines and the École Centrale to lesser schools, and you carry the status of your school within you for the rest of your life. I remember that I strongly felt the weight of tradition when I first joined the company. It is true that winds of change were already blowing then, but they were barely noticeable and needed a couple of years before really expressing themselves. But eventually the company changed its culture, and now the company considers itself an international one. I think a deep change has taken place during my 15 years with the company.

So, anyway, this was the first time I gained experience of the industrial aspect of research. My first task was to examine and synthesize different kinds of adhesion in Saint-Gobain's products and processes. I decided to simultaneously pursue fundamental reflection and a practical approach, helping the factories improve their processes. This was a very instructive experience. I learnt many things although I am not sure that I helped the factories all that much. I certainly learnt for myself that I preferred to stay within R&D and not to progress into production. On the fundamental side, I developed a network of contacts in public labs in France and the US. This became useful later on. After three years in the field, and having created a small research lab, I decided to gain some distance from the practical aspect of my work. It was also obvious to me that fundamental research was required first. Progressively the idea came to me to propose the creation a special laboratory dedicated to the basic aspects of polymer adhesion - and of course also to related issues such as the surface science of glass. But I knew that Saint-Gobain was not ready to have a laboratory for basic science by itself, so my idea was to set up a lab jointly with the CNRS. This was in 1988. From the administrative point of view this was feasible : a number of such joint ventures already existed, an example of which is Rhône-Poulenc. Of course I had to convince both Saint-Gobain and the CNRS of the utility of the project which was not straightforward. Although I managed to convince Saint-Gobain in a manner of hours, CNRS needed more prompting.

AH : Would you explain the nature of Saint-Gobain's research before your proposed laboratory ?

HA : It was a quite common kind of R&D geared towards problem solving. Helping the development of new products and solving problems within production.

AH : So the research agenda was driven by questions arising out of production ?

HA : Yes, and my idea was to get a more fundamental understanding of the questions which would enable us to help with such questions in a much better way.

Figure 1. Saint-Gobain Recherche, Paris

At Saint-Gobain I had to sell the idea primarily to the Vice-President of R&D. He took the decision just before retiring. The CNRS process was more complex. It has a democratic organization where decisions are taken by committees. The members consist of both elected researchers and individuals named by the Ministry of Research. They are divided up into different scientific sections. So here I had to convince a diverse group of people, and not just one person, as at Saint-Gobain. As I mentioned, I had developed a network of relationships in the fields of adhesion and surface science and now this turned out to be useful. I knew that many people approved of my research agenda. My project was accepted without much fanfare, but it still took a while because of the administrational hoops that a proposal has to jump through within the CNRS. They meet only twice a year, and every decision has to be validated by the CNRS directors and so on. It took maybe 12 months. The laboratory started on January 1, 1990. But there was only a building and neither instruments nor people.

Figure 2. Joint lab : Saint-Gobain Recherche & CNRS

The three yellow arrows point to the units of the joint lab within the Saint-Gobain Recherche building.

In the meantime I conferred with scientists in many other labs trying to recruit people. Of course the CNRS could not order people to go, so I had to entice scientists away. I estimated that I needed three scientists from the CNRS in addition to three scientists from Saint-Gobain. Two of the latter had already worked with me, and they followed me to the new project. A further researcher came from somewhere else – it was a young Chinese woman. We also had two or three technicians and some PhD students. Altogether, it took a year or so to gather everyone together. We also had to buy instruments and the process of getting the laboratory shipshape lasted altogether something like 2 years. We began to actually do some research in late 1990. And from then on the activities progressed rapidly. In two to three years we reached a plateau of 20 people, a level that had been stipulated by the CNRS. A third of the people had come from the CNRS, a third from Saint-Gobain, with PhD students constituting the last third.

AH : Where did they come from ?

HA : The latter were doing industrial PhDs (Contrat à Durée Déterminée) with Saint-Gobain, and their salary came jointly from the French Ministry of Research and from Saint-Gobain. Of the entire staff, about half each came from chemistry and physics. It was crucial that we develop knowledge and expertise in both these fields. Later we also developed an interest in mechanical problems.

Figure 3. The SPM from Park Scientif Instrument

AH : What was the instrumentation ?

HA : There was a conjunction of the beginning of our lab with the very early days of scanning probe microscopy. This new kind of instrumentation offered a very exciting opportunity. There was a risk in this. We purchased the first Atomic Force Microscope (AFM) ever in France. We bought it from Park Scientific Instruments. Later we built the first AFM for UHV purposes. There were many people then who thought the instrument had no future, so it was a risk to invest time and money in it.

AH : Why did people think it had no future ?

HA : The objection was that it was not clear that atomic resolution could actually be achieved with the AFM. It was not until 1993 that Binnig showed true atomic resolution.

AH : Well, yes, but before he had claimed to achieve atomic resolution. In 1993 he only claimed that so far he had been mistaken and only in 1993 did he achieve true resolution. Is that not right ?

HA : Yes. But in 1993 the community was convinced. The reason I did not hesitate was that atomic resolution was not actually the big issue for our purposes. Even a resolution of 1 nanometer amounted to a great deal. Much could be done with such a resolution in the field of adhesion, and also in fracture mechanics and surface chemistry.

AH : I have the impression that since 1995 or so many people argue that atomic resolution is not really that important, and that in the early 1990s it was still considered the holy grail. So you were unusual in that you had this attitude so early ?

HA : You are right that atomic resolution had a special ring to it in those days.

AH : Did you emphasize the issue of atomic resolution in your application to the CNRS ?

HA : I am not sure. Even today, nobody has achieved atomic resolution in glass. So it would have been a hard sell, also then. The same goes for polymers. And those two were our substances under investigation.
There is a difference between STM and AFM. They obey two different logics. The STM has remained a tool of basic research, in surface science. The AFM, even early on (and this would be interesting to discuss with Calvin Quate or Gerd Binnig), there was a hope that it could be useful, for example in other fields of science, such as mine, or in technology, such as process control, microelectronics, semiconductors, and so on. Generally speaking, in early phases there are always many people who think that a novelty will never become common. We have to remember that in 1987 or 1988 solid probe microscopes were still big and unwieldy instruments. Of course miniaturization had set in by 1990, but it was a novelty. Only very few people were convinced that the AFM would become so common. Calvin Quate is one of the few. The STM has revolutionized basic research on metals and semiconductors. There was a reaction against it, because surface science was done using diffraction techniques working in reciprocal space. Surface scientists were formed in this mode of research. They resisted the change, feeling that newcomers would enter their field without the kind of abstraction that had hitherto been key to access to the field. Working in ordinary space was too easy ! Of course it has not actually become easy because the instrument has brought its own problems, and there are still people working with diffraction and in reciprocal space. The two complement each other.

AH : So this is the background against which your decision has to be seen. You went out on a limb.

HA : Yes. The beginning of my lab coincided with the first commercial scanning probe microscopes (SPMs). We had to grasp the opportunity.

AH : How did you know about the AFM ? Was it a very visible instrument at the time ?

HA : No. I knew about it from publications, but in order to actually see an instrument, I had to travel to California - although I guess I could have seen one at IBM Zurich. There was an STM at Marseille, because two physicists there (Salvan and Humbert) had worked at IBM Zurich, and they had brought one back with them. But they had no experience with the AFM. So I went to the US and visited the very few labs with AFM, both academic labs and the start-up companies of PSI [Park Scientific Instruments] and DI [Digital Instruments]. At Stanford University I met Calvin Quate and at UC Santa Barbara I met Paul Hansma.

AH : Was there a relationship between Paul Hansma and DI ?

HA : I don't remember. But at any rate it was not as close as the one between Quate and Park. I think Park was a former student of Quate's.

AH : So you purchased an AFM from Park. What about the other kinds of instrumentation you purchased for your lab ?

HA : Yes, we had to get other instruments, partly because it took a long time for the AFM to arrive. I had to go to the US to compare the DI and the Park instruments, and I discussed it with the physicists and chemists in our lab before ordering, and then we had to wait for the delivery – maybe 4 months or so. We got a 40% discount, because we were the first French customers, and they hoped that we would open the French market for them. I had very good discussions with Quate, and I think he trusted me to be a good advertisement for him in France. I think we paid 400,000 French Francs, so that the catalogue price was in the order of 800,000 French Francs [approximately US$100,000].

We bought also an infra-red spectrometer, in order to study molecular grafting on oxides. This we used as a complement to the AFM. And as I said in a previous part of the interview, our approach was to combine the traditional surface science (very clean surfaces) with “true surfaces” interacting with the environment. The infra-red spectrometer, XPS (X-ray Photoelectron Spectroscopy), and LEED (Low-Energy Electron Diffraction) were good tools for the traditional surface science approach working in UHV Ultra-High Vacuum). And also HR-EELS (High-Resolution Electron Energy Loss Spectroscopy). Our choice was risky, but it turned out to be correct. Our decision to build bridges between the two approaches was taken in 1992 or 1993. Quite early on in our project we built a surface force apparatus (SFA). It is not at all an AFM – there is no concept of high resolution, but it is similar in that you can get a direct measurement of the force interacting between two objects only a few Ångstroms apart. The idea is to make the measurement quantitative in order to study whether the interaction is due to van der Waals or electrostatic forces. In fact this project took six years – not for technical reasons but simply because we had to get the right people.

AH : Each instrument had its strengths and weaknesses in terms of resolution and the scale of the surface analyzed. And each instrument required special skills. The AFM, for example, requires quite some expertise to disentangle signal from instrumental artifacts, right ?

HA : Yes, artefacts were a real concern at the beginning, when we all had very limited experience. We had to pay much attention in order to ascertain the results.

AH : Can you explain how one separates signal from artefact ?

HA : There are different kinds of artefact. One that now seems quite natural but was hard to understand then is the tip effect. If the surface under examination has sharper topographic features than the tip, then the tip will be imaged rather than the surface. We had trouble with this kind of artefact. In fact, when studying tin oxide deposits on some substrate we got very nice images that we at first interpreted as small crystals having the similar orientation. We were very excited to find a growth mechanism of specific orientations on isotropic surfaces such as glass. I decided to present this result at a small meeting in Davos, Switzerland. The topic there was in fact “The AFM for Technological Applications”. Famous scientists attended, including Calvin Quate, Jim Gimzewski, and Heinrich Rohrer. There were only some 10 people there, because this was very early, maybe 1991. The night before my presentation, I began to wonder that the result was really too beautiful to be true. I telephoned my lab and asked people there to turn the sample by some angle and do the experiment again. That way, the features should have changed if they belonged to the surface. But they did not, and so we knew that the features belonged to the tip. So I did not present that particular slide in my talk.

AH : So rotating the sample by some degree is one way of identifying artefacts.

HA : Yes, that will eliminate this kind of artefact, the tip effect. There are also adhesion artefacts, some of which have been solved in the meantime thanks to new recording techniques such as the tapping mode.

AH : Digital Instruments has a patent for the tapping mode, right ?

HA : Yes.

AH : So the Park instrument that you bought did not have the tapping mode ?

HA : No it did not. The tapping mode did not become available until 1993 or so. Later on, Park Scientific Instruments did do something similar, but they may not call it tapping mode. The DI patent covers the name. And in the straightforward contact mode many artefacts were possible ; for example when looking at soft materials and polymers surface scratches easily occur. If you do that you image the substrate only. One way to identify this effect is to scan again with a smaller tip-surface interaction. In some cases you will find miniature small squares where the surface had been damaged in the course of the first scan. Some artefacts are very common, others are quite specific and harder to identify.

AH : In what you have explained, the identification of artefacts is internal to the instrument itself. It is not that you can go and compare the results of an AFM scan with those from a different instrument ?

HA : You can change the tip, and you should identify artefacts unless you are very unlucky to get the same tip. Everybody understood that the AFM has great potential not just as an imaging instrument but also to measure adhesion, hardness and so on.

AH : Using force-distance curves ?

HA : Yes, force-distance curves. This turned out to be very useful for us. For instance in order to understand the electrostatic interaction between oxide and a silicon nitride tip under water. This was original work. For example, in polymer adhesion we checked if it stayed on the substrate and what scratching would do. Of course such ideas were floating around at the time.

AH : Were you important to the subsequent spread of the AFM in France ?

HA : Yes, people came to our lab. Another lab, at the Institut Curie, that got an AFM at almost the same time. For a while we were a small community but then gradually we grew larger and larger. Yes, we were the pioneers. It was exciting.

2001-02-20 :

HA : I went with one of my sons who was 11 years old at the time to see Park Scientific Instruments. There were no more than 10 people working there, in fact I think it was more like three. It was very small and familial. We discussed and had tea. I enjoyed discussing with these people. It was nothing like an established company.

AH : What did it look like ? Did they work out of a garage ?

HA : Something like between a home and a garage. It was a small house. Even Digital Instruments started out like this. Already in those days DI, and especially Virgil Elings, was much more commercially aggressive, but they were very small too at the time.

AH : Did you stay in touch with some of these guys ?

HA : I stayed in touch with Calvin Quate for five or six years, until 1996. After that I lost the contact but he will probably remember me because we had many discussions. It was curious to see his impact upon materials science. In fact it was very difficult for him to get the first paper on the AFM accepted in Physical Review Letters. Some of it was considered just a pure mechanical profilometer. It had good resolution but it was not really anything new. His project now is very interesting from what I can tell reading his articles in the scientific journals. And he really is a very nice person. Maybe the last time I saw him is when I invited him to give a talk at Saint-Gobain Recherche.

AH : So you stayed in touch with him in the early 1990s, while you were developing your own AFM. I guess the use of the AFM changed the project from what you had originally envisaged ? Did you continue using all the other tools or did you focus exclusively on the AFM ?

HA : We used the other tools.

AH : What did you buy for your laboratory ?

HA : Infrared spectrometer, XPS, HR-EELS (High Resolution Electron Energy Loss Spectrometer), LEED. Quite quickly we had three AFMs. I wanted to develop a PSTM working in the infrared but unfortunately that particular project died because the physicist we had working on it left.

AH : What journals show the history of these instruments best ?

HA : In the beginning it was mainly in the general physics journals such as Applied Physics, Applied Physics Letters, Physical Review Letters, Surface Science. Now there are specialized journals. A journal like Journal of Scientific Instruments is not so important in this respect. Langmuir is also important for soft matter.

AH : Do any of these journals have review articles ?

HA : I am almost sure that all of them do.

AH : We were talking about the various instruments you had in your lab. How did you apply them to your research project ?

HA : The idea was to have two parallel approaches. We were mainly interested in adhesion, molecular grafting and so on. One approach is the classical view of surface science, the ideal surface approach. The other is the REAL surface approach, taking the environment as a part of the system.

AH : Not working in Ultra-High Vacuum (UHV) ?

HA : Yes. But we were trying to make the two approaches meet.

AH : So when you started working with the AFM in UHV, the point was to simplify the experiment ?

HA : Yes.

Figure 4. UHV Chamber et AFM in UHV Chamber

If a probe were to be introduced directly into the UHV chamber, it would take days of pumping to achieve UHV. Instead, it is first introduced into an antechamber, whereupon a vacuum is produced there. Only then can walls be opened without reducing the UHV too much. By pushing the rods labelled 1 and 2, the sample is transported in successive stages into the central chamber. Several instruments are attached to the chamber, including an XPS. On the right, an AFM can be discerned in the UHV chamber.

AH : How did the various instruments complement each other ?

HA : The spectrometers provided structural information. They give a chemical signature. One point of interest was silver on magnesium oxide. In order to have a simple model of glass we chose to study this problem within pure single crystal. We had the probe in situ in the same UHV chamber where we had the instruments to add the deposition techniques. In the case of silver it was just thermal evaporation. We wanted in situ real-time studies of the atoms arriving upon the substrate, the oxide surface. There were two models in this problem. One was that the atoms remain isolated or form small islands, so that the growth process is two-dimensional, so that you first get a perfect monolayer before a second layer is started upon. The other is that growth is three-dimensional with occasional collapses into flatness. To study this it is of course useful both to look directly and to use diffraction techniques. But in order to understand the process you need to grasp the interaction between the silver and the oxide. And only spectroscopic techniques will help here. We always tried to look at a problem from two differing points of view – in this case geometrical and chemical.

AH : You make it sound easy. You just use one tool and you get the topography, and then you use another and you get the chemical composition.

HA : Well of course it is not at all easy. It was very difficult because for instance, the STM works very well when you have a smooth surface but when you have corrugation it becomes much more difficult, because this corrugation interferes with the instrument. In spectroscopy you integrate over the size of the beam which is much larger than the surface scanned by the AFM. So you have to do many different experiments to see what effect the temperature has and so on. You also have to model the interaction. This was a little known problem. What is the mechanism of very small silver clusters on magnesium oxide with other silver clusters in the neighborhood ? It was a new problem. So it took time to understand the system.

AH : What is the measure of success ? It was partly CNRS, so you were under pressure to publish ?

HA : Yes.

AH : And since it was partly Saint-Gobain you had to get patents ?

HA : We had to do both. It was an interesting exercise in communication. In my position as head of the lab, I could not use the same words, the same way of presenting things when addressing different audiences. From time to time it was necessary to gather the scientific and the industrial people together under one roof.

AH : And what language did you speak then ?

HA : Fortunately everyone was happy with this lab, so it was not quite so difficult. The conditions were good. Nonetheless your question is quite correct. It was interesting.

AH : How did you convince Saint-Gobain that this would have a pay-off ? And how did you negotiate long- and short-term goals ?

HA : The short term was a problem. It was not straightforward to plan a new product for the company. The pay-off was very diffuse and difficult to identify. One way of motivating the directors was the argument that we trained very good PhD researchers for Saint-Gobain. And this was not expensive for Saint-Gobain, because they shared all the expenses with CNRS. Up until now this has not been a problem.

AH : Stanley Whittingham told me that in the last 15 years or so there has been a tremendous shift in company planning towards the short term in industry. Partly this was due to the MBA education and the fanning out of this new generation of business administrators into all nooks and crannies of industry. As a result the long-term disappeared, because everything had to fit into the financial year so that you have something to show to your shareholders.

HA : It is true that this has taken hold in industry. We had the good fortune that it was not very developed in Saint-Gobain. But also, the time required for the development of new glass materials just is acknowledged to be greater than that in electronics or informatics. When we start new projects, we are simply not able to show a product six months later. So we are less exposed than people in other fields, but the general development that you alluded to certainly has taken place. Maybe our situation will also change in the future. We may be excessive.

AH : Has the accountancy changed for you ? Did you have to write annual reports ? And has it changed over the last ten years ?

HA : In general ?

AH : Well, for the CNRS I can sort of imagine it. In academia you would specify the number of publications that you have produced and that is the measure. End of story. And that is very simple accountancy. But if you account to a company, keeping in mind the increasing influence of MBAs : did you have to account for your expenses in ever greater detail ?

HA : I do not think there has been such a change in the last decade.

AH : And do you write annual reports ?

HA : Bi-annual. But I am not in this lab anymore ; I left two years ago.

AH : Okay, so during the 1990s up until two years ago you wrote biannual reports to the company and in that period the structure of the reports did not change.

HA : That is correct.

AH : Did you have to specify just how much money you spent ?

HA : Yes, but also there, no change took place. And I always reported to the same person within Saint-Gobain. He was basically content with what we did, so it was never critical. It is true, it might have changed with a different person in charge.

AH : So, how did the instrumentation change throughout the 1990s ? The AFM became commercially available to an ever greater extent, you were able to buy many more things off the shelf. Is that true also of all the other instruments ?

HA : Yes, there are different aspects to your question. We used to build many instruments ourselves, and this was of great use for training. And this has changed. A reason the French PhD has been shortened is that equipment is being bought and not made in-house. That is a general trend. Science is changing as a result, because using a commercial instrument is not the same. When you develop an instrument yourself you know exactly how to get the result. In the specific case of AFM/STM : probably the AFM has been developed much more than the STM. In the STM the major breakthrough was with the driver and that was quite early. I think it was possible to purchase an STM driver already by 1992. Variable temperature was a little more difficult, but it was certainly available by 1994. Different ways of scanning and acquiring information were developed. Otherwise the evolution was purely technical : cheaper, and more diverse (such as an STM expressly for electrochemical research). By contrast the AFM has developed rapidly. Tapping mode and other modes where you measure not only the distance but also hardness, conductivity, adhesion, chemistry. It has become possible to map all these parameters. This explains why more and more people use the AFM.

AH : It has also become cheaper, right ?

HA : Yes.

AH : It has certainly become more user-friendly, adaptable to different circumstances.

HA : Yes. For the STM : there have very beautiful studies made of the coupling between tunneling and modulation. You might modulate the tunneling current with light for instance. You can even leverage the spin of the tunneling electrons. So you can do beautiful physics. But this contributes little to the democratization of the technique.

AH : I have the sense that Calvin Quate, by contrast, is working hard to increase throughput.

HA : Yes, that is right. There can be two reasons for doing that. To make the investigated part of the surface larger – of use in the semiconductor industry. And to shorten the time required for a scan. He is trying to use the system technologically.

AH : Okay. Two years ago you left your lab. Your own lab. Why ?

HA : I wanted to try something new and I was lucky to find someone who was well capable of taking over and for whom I have a lot of respect. He is from a different background. So now it is a different group. I became the Scientific Director of Saint-Gobain Recherche. There are two parts to the job ; one is to be the scientific manager, the other is to establish contacts in the outside world, and to promote innovations within the company, for instance with the marketing people.

AH : You were promoted ?

HA : Yes.

AH : And you have become slightly removed from lab work ?

HA : Yes, completely, I am now involved in organizational work.

AH : In fact, our project resembles your job in the sense that we stand back and look at the scientific research and try to gain a perspective ?

HA : Yes, you could say that.

Fin de l'enregistrement

Pour citer l'entretien :

« Entretien avec Hervé Arribart », par Arne Hessenbruch, 19 février, 29 mai et 20 février 2001, Sciences : histoire orale, /spip.php ?article47.

Pour citer l'entretien :

« Entretien avec Hervé Arribart », par Arne Hessenbruch, 19 février, 29 mai et 20 février 2001, Sciences : histoire orale, https://sho.spip.espci.fr/spip.php?article47.

Lieu : dans le salon (les 19 février et 29 mai 2001) et dans la petite salle de réunion (le 20 février 2001) du Dibner Institute, Etats-Unis.

Support : enregistrement sur cassette.

Transcription : Arne Hessenbruch.

Édition en ligne : Sophie Jourdin, Sacha Loeve.

GOODENOUGH John B., 2001-05

2010-02-04T14:39:22Z

John Goodenough, né en 1922 à Iena (Allemagne), est professeur et détient la Virginia H. Cockrell Centennial Chair in Engineering de l'University of Texas, Austin. Jeune homme, il s'est porté volontaire pour servir dans l'armée US comme météorologiste au cours de la Seconde Guerre mondiale. Après la guerre, il a étudié la physique à Northwestern University (près de Chicago) puis a travaillé au Lincoln Laboratory du MIT (Boston, Mass.) et dirigé l'Inorganic Chemistry Laboratory à Oxford University (Angleterre). Ses recherches portent sur les propriétés électroniques et ioniques des oxydes métalliques à la croisée de nombreux champs de recherche. Il a reçu le Von Hippel Award de la Material Research Society (MRS) en 1989 pour sa contribution à l'étude des solides où il s'est illustré par ses aptitudes à constamment lier les concepts de base de la physique et de la chimie à un large éventail de sujets théoriques. Goodenough est aussi reconnu comme l'un des scientifiques les plus influents des solid state ionics, champ de recherche sur les électrolytes solides.

BERNADETTE BENSAUDE-VINCENT (BBV) : So where did you start ? You graduated in chemistry, no ?

JOHN B. GOODENOUGH (JG) : No, not at all. Before World War II, I studied classics and mathematics. I took an introductory course in chemistry my freshman year at Yale as my science requirement for a Liberal Arts degree, but I had no thought of a career in science.

I had been awakened intellectually and spiritually while reading poetry at Groton School and trying to understand the metaphors of the Bible and the Church. Therefore, at Yale I was a young man in search of a calling for my life, so I read considerable philosophy. I became intrigued by the philosophy of science, and as I was reading Whitehead's Science and the Modern World, I came to the conclusion that, if I were ever to come back from the war and if I were to have the opportunity to go back to graduate school, I should study physics.

As an Army Air Force meteorologist, I dispatched tactical aircraft across the Atlantic Ocean during World War II. In 1946, while I was still stationed on the tiny island of Terceira in the Azores awaiting my turn to go home, a telegram arrived telling me to report back to Washington in 48 hours. In Washington, they sent me to Chicago where I was to have a choice to study physics or mathematics at either the University of Chicago or Northwestern University. My old Yale mathematics professor, Egbert Miles, had not forgotten me ! Confronted with this opportunity, I had a flashback to the evening I sat reading Whitehead before the military interruption. It seemed to me that "This is what I am supposed to do !" The next day I went to the University of Chicago to register for graduate studies in physics. When I arrived, the registration officer, Professor Simpson, said to me, " I don't understand you veterans. Don't you know that anyone who has ever done anything interesting in physics had already done it by the time he was your age ; and you want to begin ?"

BBV :It was really encouraging.

JG : Well, it didn't bother me at the time. I was simply grateful that, though still in the Army, my transition back to civilian life was so smooth. I left the Army in 1948 and continued my studies with the G. I. Bill of Rights. When I completed the 32-hour qualifying examination, I decided I did not want to go into nuclear physics, so I signed up to do my dissertation in solid-state physics with Professor Clarence Zener. When I finished my Ph.D. thesis, I had two job offers : one was to be an assistant professor at the University of Pennsylvania and the other was to join the Lincoln Laboratory of the Massachusetts Institute of Technology (MIT). I chose the latter.

ARNE HESSENBRUCH (AH) : What year was that ?

JG : That was 1952. Lincoln Laboratory had been established by the Air Force to develop the Semi-Automatic Ground Environment (SAGE) system for air defense. The system integrated radar, communications. and the digital computer. At that time the digital computer didn't have any memory other than a 16 x 16 bit electrostatic storage tube. Jay Forrester, an electrical engineer, had invented the coincident-current magnetic-core memory. This memory uses a magnetic torroid (core) with a square B-H hysteresis loop for each bit of stored information. Forrester had noted that the magnetic alloys Deltamax and Permalloy had the required square B-H hysteresis loops, and he had used them to prove the concept of his memory. However, the switching speeds were too slow. As an electrical engineer, he assumed the problem was eddy-current damping in his metallic cores, so he had ordered tape cores that were rolled to thicknesses as small as 1/8 mil. But the switching speed was still an order of magnitude too slow. Therefore, he had decided to investigate ferrimagnetic oxides that were insulators. My assignment was to help design a ferrimagnetic oxospinel that had a square B-H hysteresis loop. Those in Europe who had developed the ferrimagnetic spinels did not attempt to do this as they were convinced it was theoretically impossible. The problem was that you cannot role a brittle oxide as you can a metallic alloy in order to align the easy-magnetization axes of all the individual grains of a polycrystalline core, which is how the square B-H hysteresis loops are obtained in Deltamax and Permalloy.

The first thing I did was to analyze what controls the shape of a B-H hysteresis loop. I calculated where the domains of reverse magnetization are nucleated and what hinders their growth in a magnetic field. My calculations showed that if the crystallographic axes of easy magnetization are not well-aligned across a grain boundary, magnetic poles at the boundary may induce nucleation of reverse domains even where the applied magnetizing field is opposed to the magnetization in these domains. However, because the magnetization of a ferrimagnet is much smaller than that of a ferromagnet, nucleation of the reverse domains does not occur in a ferrospinel even where the easy-magnetization axes are misaligned until the magnetization is in the direction of the reverse-domain magnetization. This result meant that it was theoretically possible to obtain a square B-H hysteresis loop in a ferrimagnetic ceramic with unaligned grains provided some other defect could be introduced that would not only nucleate reverse domains at a desired reverse field, but would also release them, once nucleated, to grow until they reversed the magnetization. This was an important finding.

I also analyzed the factors that controlled the switching speed of a magnetic core. It was immediately apparent that the driving field to switch a core was restricted in the memory application to a magnetic field strength H = (H - Hc) < Hc where Hc is the threshold field to switch the magnetization direction. The coercive field Hc in the Permalloy tapes was too small to allow the driving force needed for fast switching. Moreover, the analysis showed that there is an intrinsic damping of spin rotations that would still be present in the absence of eddy currents. It was therefore clear that a somewhat larger coercive field Hc than that of Permalloy was needed, and the remaining problem was to discover the appropriate imperfection that should be introduced to provide many centers for nucleating domains of reverse magnetization at an acceptably large H » Hc.

Meanwhile, my colleagues were empirically mapping the MnO-MgO-Fe2O3 phase field to determine the compositional range of the ferrimagnetic spinels and the influence of annealing temperatures on the shape of the B-H hysteresis loop. It was in this phase field that promising hysteresis loops had been published. We found a certain compositional range rich in manganese in which the spinels were tetragonal rather than cubic. Previous workers had assumed that the tetragonal distortion was due to the disproportionation reaction 2 Mn(III) = Mn(II) + Mn(IV) since this reaction had been observed at the surface of Mn(III) oxides in acidic solution. However, I had read Pauling's The Nature of the Chemical Bond, which helped me to observe that the Mn(III) ion had an orbital degeneracy in a cubic octahedral site that would be removed by a distortion of the site to tetragonal symmetry. I therefore reasoned that at a critical Mn(III) concentration, there would be a cooperative orbital ordering that minimized the elastic energy and that the tetragonal distortion we observed was due to such a cooperative orbital ordering. Unknown to me at the time, Jahn and Teller had pointed out some years earlier that a molecule with an orbital degeneracy would distort so as to lower its energy, but my deduction was the first realization that, in a solid, cooperative orbital ordering to minimize the elastic energy would induce a crystallographic distortion below a transition temperature Tt. This effect is now known as a cooperative Jahn-Teller distortion. At higher temperatures and lower concentrations, the individual site distortions would be disordered and would fluctuate in what is known as a dynamic Jahn-Teller distortion. We also noted that we could obtain square B-H hysteresis loops in compositions that were cubic, but close to those that became tetragonal below a Tt, if the cores were annealed for a specific period at a precise temperature. In this way the technical problem was solved empirically ; the coincident-current magnetic memory proved to be a critical step in the development of the digital computer. However, I didn't know until some time later how the annealing procedure introduced defects that nucleated domains of reverse magnetization.

AH : When did you find this out ?

JG : The Russians were interested in our development of a computer memory. Therefore, I was invited to Sverdlovsk (now Katerinaberg) in 1961 to talk about our work. While there, Shur showed me evidence that the domains of reverse magnetization were nucleated within the grains and not at grain boundaries. In a 1964 experiment concerned with Li+-ion ordering on the octahedral sites of the spinel structure, I observed that the Li+ ions ordered with all trivalent counter cations except Mn(III). I then realized that annealing the memory cores for a specified period at a precise temperature was creating Mn(III)-rich chemical inhomogeneities within the cubic structure in order to reduce, through cooperativity, the elastic energy associated with dynamic Jahn-Teller fluctuations. These chemical inhomogeneities created magnetic poles within grains that were acting as the nucleation centers for reverse-magnetization domains in the memory cores.

BBV : So this is how you came to study oxides ?

JG : Yes. But let me tell you of one other deduction I made at that time that proved critical for my future studies. Néel had understood that the interactions between localized atomic moments may be antiferromagnetic as well as ferromagnetic. An open question at that time was the origin of the magnetic interactions and what determined their sign. Following a suggestion by Kramers, Phil Anderson had formulated the antiferromagnetic superexchange interaction in his Ph.D. thesis with Van Vleck. At the same time, neutron diffraction was developed as an experimental tool with which to measure directly the magnitudes of the atomic moments and their order below a long-range magnetic-ordering temperature. Wollan and Koehler had determined that the magnetic order in the antiferromagnetic perovskite LaMnO3 consisted of ferromagnetic (001) planes coupled antiparallel to one another along the c-axis (Figure 1 below). In La0.5Ca0.5MnO3, the magnetic order within the (001) planes consisted of both ferromagnetic and antiferromagnetic interactions. This anisotropic character of the sign of the (180o - f) Mn-O-Mn interactions in the pseudocubic MnO3 array was a mystery that delayed publication. I realized that the anisotropy must reflect a cooperative orbital ordering at the Mn(III) ions. As I had already worked out in my mind rules for the sign of the superexchange interactions that depended on the occupancies of the interacting orbitals, it was possible to predict the cooperative orbital ordering in LaMnO3 and the charge and orbital ordering in La0.5Ca0.5MnO3 so as to account for the magnetic order. We published back-to-back papers in the Physical Review. Kanamori subsequently provided a more mathematical formulation for the superexchange interactions, and the rules I formulated then are known as the Goodenough-Kanamori rules for the sign of a superexchange interaction. With these rules it has been possible to understand a variety of complex magnetic orderings in magnetic materials. Moreover, these studies led me to an investigation of the change from localized-electron configurations coupled by relatively weak interatomic superexchange interactions to itinerant electrons where the interatomic interactions become stronger than the intraatomic interactions. They also made me realize that, as a physicist, I could play a scientific role building a bridge between the engineer needing a material to realize a device and the chemist charged with the problem of designing a material that would perform the engineering function.

Figure 1. Perovskite structure

AH : And this realization came to you in the mid 1950's ?

JG : Yes, but its evolution was a bit more complex. When we had completed our project with the memory cores and working memories were being realized, Jay Forrester called us to his office. We expected to get a pat on the back, maybe a promotion. Although he spent 30 seconds congratulating us on a job well done, he had another purpose. "Now that you have worked yourselves out of a job, what are you planning to do ?" he asked.

AH : What an interesting managerial technique.

JG : Half the group decided to take the technology to industry ; I decided to stay and spent the next weekend figuring out what I should do next. I came up with the idea of a magnetic-film memory that would switch by a simultaneous rather than a sequential rotation of spins.

AH : Do you remember when that was ? Do you remember the year ?

JG : I believe it was 1956 or 1957.

BBV : So you stayed at the MIT Lincoln Laboratory for that ?

JG : Yes. I was put in charge of this new project as well as of the old ceramics laboratory. Since several people had left, I was permitted to hire a few new people. One of those I hired turned to me about a year later and said, "I want to become famous ; let me take charge of the magnetic-film project." He was an experimentalist, so I said, "All right, you can have it !" I gave my full attention to what was left of our ceramics laboratory. It turned out that the magnetic-film memory only filled a small niche in the market. It proved a difficult technology, and other developments came along that were more competitive. It appeared to be a good idea at the time, but it didn't become a winner. However, my decision to give the magnetic-film project to others made me concentrate on solid-state chemistry and gave me about 12 years in which I did some fundamental studies and wrote two books.

BBV : Which one : Metallic Oxides ?

JG : I wrote first Magnetism and the Chemical Bond. I realized I could tell a great deal about the nature of the chemical bond from the magnetic order and the crystallographic distortions because I knew how the signs of the interatomic exchange interactions depend on the number of electrons in the interacting orbitals and how cooperative orbital ordering would optimize the exchange interactions. In those days many people were interested in investigating the complex magnetic orderings revealed by neutron diffraction and in interpreting the origins of these complex orderings. For example, I was able in 1961 to show that where the Jahn-Teller distortions are fluctuating, the (180o-f) Mn(III)-O-Mn(III) interactions in a perovskite became isotropic, ferromagnetic vibronic superexchange interactions. Vibronic superexchange interactions are now returning as a subject of interest ; and we have recently shown they play an important role in the manganese oxides that exhibit a colossal magnetoresistance. Moreover, Tom Kaplan of my group was calculating the ground-state magnetic order where there were competitive interactions that gave rise to spiral-spin configurations, configurations that were quite complex in spinels where a spiral-spin configuration was superimposed on a Yaffet-Kittel triangular-spin configuration. I extrapolated the rules for the superexchange interactions to the case of itinerant-electron magnetism, reasoning that it was the perturbation expansion of the mathematical description and not the physics that broke down at the crossover from localized-electron to itinerant-electron magnetic interactions. In that book, my primary interest was in the variety of magnetic orderings that were observed in the d-block transition-metal alloys and compounds.

My book Les oxydes des métaux de transition is a French translation of a long review article entitled "Metallic Oxides". This review was an extension of my former book ; it concentrates on the transition from localized to itinerant electronic behavior. Localized-electron behavior occurs where the intraatomic interactions are stronger than the interatomic metal-metal or metal-anion-metal interactions, which is why the interatomic interactions between localized-electron configurations can be treated in second-order perturbation theory. The conventional one-electron band theory of itinerant electrons applies where the interatomic interactions are much stronger than the intraatomic electron-electron interactions. While I was still a graduate student, Mott had called attention to the fact that NiO should be a metal rather than an antiferromagnetic insulator according to the band theory. It is necessary to introduce into this theory the on-site electron-electron interactions to account for the localized-electron configuration of NiO. Hubbard presented the Hamiltonian that introduced this term, and the transition from antiferromagnetic insulator to Pauli paramagnetic metal where a band is half-filled is called the Mott-Hubbard transition. I realized that in oxides the metal-oxygen interactions open a large energy gap between the bonding and antibonding states of the valence s and p electrons ; d-electron redox energies may be found within this energy gap. Moreover, isostructural oxides were known of which some members were metallic and others were antiferromagnetic insulators. For example, TiO is a metal whereas MnO is an antiferromagnetic insulator ; SrVO3 is a metal whereas LaVO3 is an antiferromagnetic insulator. These observations meant that I should be able not only to determine the number of electrons in a d-electron bond from the sign of the spin-spin interaction across it but also to study the transition from localized to itinerant electronic behavior in d-block transition-metal oxides without the interference from overlapping broad bands that occurs in the magnetic alloys. However, our experiments designed to monitor this transition were frustrated at that time by lattice instabilities that gave rise to either phase separation or the appearance of a charge-density/spin-density wave (CSW/SDW). Before we could unravel why this was so, Senator Mansfield passed an amendment that forbade federally supported facilities like Lincoln Laboratory from engaging in fundamental research not targeted on a specific engineering application. So, I was told I could no longer continue my fundamental studies.

AH & BBV : When was this ?

JG : It was about 1970. So I had had about 12 years from 1958 to 1970 to do fundamental research.

AH : Was all of this done at Lincoln Laboratory ? Were you involved in the organization of the Department of Materials Science and Engineering at MIT ?

JG : Yes, the work was done at Lincoln Laboratory. No, I was not involved with the MIT-campus bid to establish an NSF-sponsored Materials Science Institute.

To return to my story, when I was told I couldn't continue untargeted fundamental research, I was forced to think through what I and my group should do next. It was the early 1970's, and the first energy crisis had arrived. People were lined up at the gas stations. So it seemed obvious that I should consider doing something related to energy.

AH : But there is a gap of more than a year because the energy crisis was in 1973.

JG : Yes, there was a gap during which time I developed a sole for a travelling-wave amplifier ; we made a MgO-Au composite that improved the secondary-electron emission by over a factor of 100. But the project manager who requested this development became preoccupied with a big radar sink for money, so the development was never exploited.

In the same period, researchers at the Ford Motor Co. had discovered fast Na+-ion conduction in a ceramic, sodium-beta-alumina. They proposed using it as the electrolyte and separator of a Na-S battery that used molten sodium as the anode and a molten sulfur compound as the cathode. It would operate at 300o C. I was asked by the DOE to be on the evaluation panel of this project. It was my introduction to solid alkali-ion electrolytes and to batteries. I was subsequently invited to Stanford University for two days to give a seminar on my work on the electronic properties of oxides with the perovskite structure and to interact with various solid-state research groups there. Each professor had his own fiefdom, and one of those was under Bob Huggins who asked me, "How would you design a Na+-ion electrolyte ?" Since perovskite-related materials were on my mind, I replied, "I would choose a host framework that contained tunnels as occurs in the hexagonal sodium-tungsten bronze, but I would choose structures in which the tunnels run in more than one direction and intersect one another. I would also choose a main-group element rather than a transition-metal atom as the framework cation to obtain a solid electrolyte, i.e. a framework that is not an electronic conductor." As I was flying back to Boston, it occurred to me that sodium-beta-alumina was a framework structure in which the mobile Na+ ions move in planes containing intersecting tunnels. I was interested to learn that, subsequent to my visit, Huggins and his post-doc Stan Whittingham used hexagonal tungsten bronze as a sodium-insertion electrolyte for measuring Na+-ion electrolytes. Meanwhile, I had decided to investigate Na+-ion conductivity in framework structures having tunnels running in three dimensions as I reasoned that a ceramic with three-dimensional Na+-ion conductivity would be superior to one with only two-dimensional Na+-ion conductivity. I embarked on this study before I turned to the problem of clean energy.

An analysis of the energy problem showed that there were only four alternatives to fossil fuels as energy sources : hydropower, geothermal, solar (including wind), and nuclear energy. Hydropower was already being exploited and geothermal energy is geographically limited. I didn't want to consider nuclear energy, so I analyzed the solar-energy problem.

AH : Why didn't you want to do nuclear ?

JG : I wasn't a nuclear scientist and we weren't a nuclear laboratory, so it wasn't appropriate for us. Similarly, wind energy was not matched to my interests. It would have been appropriate for us to work on photovoltaic cells, but others with more experience of broad-band semiconductors were doing photovoltaic development, so I began with wavelength-selective films for passive thermal heating. We developed some of these, but I soon realized that long-term energy storage was a key to harnessing solar energy. Since energy is most versatily stored long-term as chemical energy, I had the idea to generate hydrogen from water by photoelectrolysis. I soon discovered that Fujishima and Honda had already discovered this effect on TiO2 I also proposed the use of yttria stabilized zirconia for the electrolyte of a solid oxide fuel cell to be operated with the waste heat of a conventional power plant. As a third leg, I proposed continuing work on Na+-ion solid electrolytes for the Na-S battery. In that effort, I identified several framework structures (I called them skeleton structures) that supported three-dimensional, fast Na+-ion conductivity. One of these was Na1+3xZr2(P1-xSixO4)3, which has the hexagonal Fe2(SO4)3 framework. My colleagues named it NASICON, standing for NA SuperIonic CONductor, just as I was leaving Lincoln Laboratory.

AH & BBV : Who chose that name ? What was the name of your colleague who coined the word NASICON ?

JG : There were two I think : Alan Strauss and Kirby Dwight. When I requested funding to work on these energy products, the bureaucrats in Washington said, "The National Atomic Energy Laboratories are in trouble because atomic energy has gone out of favor. Therefore, the DOE will only support energy programs in these laboratories. Lincoln Laboratory is an Air Force laboratory and should involve itself with problems directly related to the Air Force." Therefore I decided that I should leave the MIT Lincoln Laboratory.

I had always wanted to help the third-world countries, and solar energy was a program that would be well suited to some of the countries newly enriched by the increase in oil prices. Therefore, when I was approached by an Iranian about the possibility of heading up a research institute in that country, I decided to explore the idea. I went to Tehran and raised $7 M from the Shah for an institute to be associated with the Aryamehr University there.

AH : When was this ?

JG : 1974 and 1975. While contemplating back in Boston whether to make such a move, a letter from Oxford University, England, arrived asking me to put my name in nomination for Professor and Head of the Inorganic Chemistry Laboratory. My wife did not hesitate to recommend that I put my name in nomination, and I thought, "If the people at Oxford have that much imagination, then perhaps that is what I should do." I was duly elected, and in 1976 I took up the post in Oxford.

BBV : So you abandoned your Iranian project ?

JG : I did.

BBV : And the $7 M ?

JG : Yes. As it turned out, within two years the Shah was ousted, the American Embassy was taken hostage, and the Institute I had helped establish was abandoned. My election as Professor and Head of the Inorganic Chemistry Laboratory at Oxford was quite extraordinary as I had had only one course in Qualitative Chemistry as a Yale freshman in 1940 and one in Organic Chemistry in 1948 at the University of Chicago. I came into Chemistry by the back door working with solid-state chemists trying to build a bridge between them and the engineer and using their expertise to design experiments to explore fundamental physics questions in solid-state science.

AH : Is that what the Oxford Inorganic Chemistry Laboratory was interested in ?

JG : The Oxford Inorganic Chemistry Laboratory included preparative organometallic chemistry, chemical crystallography, bioinorganic chemistry, thermodynamics, electrochemistry, and several spectroscopic groups as well as solid-state chemistry. My predecessor, Professor Stuart Anderson, was a solid-state chemist, and there was a preference to maintain continuity in that field. As I had been working with solid-state chemists, I presume the Dons thought I would bring a solid-state program that complemented other on-going activities there.

Initially, I decided to investigate the chemistry of the photoelectrolysis of water on oxide surfaces and to extend my studies of ionic transport in solids to include proton conduction in oxide-particle hydrates and insertion compounds for cathodes of rechargeable lithium batteries. These topics introduced me to electrochemistry as well as to catalysis, and I later undertook studies of methanol oxidation at the anode of a direct methanol-air fuel cell, of the oxygen-reduction reaction at fuel-cell cathodes, and the mechanistics of a partial-oxidation reaction on phosphopolymolybdates. The study having a large commercial impact was the development of a cathode for the lithium-ion rechargeable batteries that have enabled realization of the cellular telephone and laptop computers, for example.

In the early 1970's, Ted Geballe and his student Fred Gamble were investigating at Stanford the insertion of various chemical species between the layers of the metallic sulfide TiS2 in order to demonstrate the existence of two-dimensional superconductivity. Michel Armand, then a student with Bob Huggins, was interested in the possibility of reversible alkali-ion insertion in TiS2 for use as a battery electrode ; Stan Whittingham of Huggins' group had used hexagonal tungsten bronze, a one-dimensional Na+-ion conductor, as an electrode, and TiS2 offered two-dimensional conductivity. Brian Steele of Imperial College, London, suggested at a meeting (proceedings edited by Van Gool) the use of TiS2 as the cathode of a lithium battery. At that time, about 1973, the energy crisis had stimulated the EXXON corporation to expand into an energy company ; Stan Whittingham and Fred Gamble were hired to initiate an energy program. Before I left for Oxford in 1976, Stan Whittingham published a paper in Nature showing that lithium can be inserted rapidly and reversibly into TiS2 over the entire solid-solution range LixTiS2, 0 < x < 1, and that the compound gives a fairly flat open-circuit voltage versus a Lithium anode of about 2 V. This publication generated extensive interest, and EXXON committed considerable resources to the commercialization of a Li/LiClO4/TiS2 battery. However, a passivation layer at the anode resulted in lithium dendrite formation on recharge. After a few cycles, the dendrites grew across the explosive LiClO4 liquid electrolyte, shorting out the cell and blowing up the laboratory. Safety concerns eventually led EXXON to abandon the project and, subsequently, its expansion as an energy company.

As a consultant for the DOE on the Na/S battery, I had become increasingly aware of these developments. It became clear to me that to avoid these safety problems, it would be necessary to develop an anode that was an insertion compound. However, such an anode would lower the voltage of the cell. I considered the origin of the metallic conductivity of TiS2 and understood that it would be necessary to insert lithium into a metallic oxide if a larger cell voltage was to be obtained. However, unlike the sulfides, there are few layered oxides. On the other hand, there are several LiMO2 compounds having a transition-metal atom M that have layered structures analogous to that of LiTiS2, so I decided to investigate how many Li atoms can be removed before the oxide structure becomes unstable. Extraction of lithium meant operating on the M(IV)/M(III) redox couple. To obtain a large cell voltage, I wanted a cation for which the energy of the M(IV)/Mn(III) redox couple was unusually low ; and to prevent migration of M cations into the depleted lithium layer, I wanted both the M(IV) and M(III) species to have a strong octahedral-site preference since migration was through a tetrahedral site. Therefore, I chose chromium, cobalt, and nickel as possible M atoms. At that time, Koichi Mizushima was visiting me from the University of Tokyo, so I asked him to perform the experiments. We were delighted to find that we could take out most of the lithium from the cobalt and nickel oxides without migration of these cations to the depleted lithium layers. However, stable reversible lithium extraction is restricted to 50% - 60% extraction. Nevertheless, this amount gave a reasonable cell capacity at a voltage versus a Lithium anode of about 4 V.

At that time, all we had was a cathode material. The British battery makers were not interested ; they could not imagine beginning with a discharged cathode. A Japanese worker at Sony had been quietly investigating a special waste carbon as an anode host for the insertion of lithium in order to circumvent the safety problem of the battery, and he recognized immediately that my cathode was what was needed to make a high-energy-density rechargeable lithium battery. The Sony Corporation was looking for such a battery to enable marketing of the cellular telephone and the laptop computer. They have done an excellent job of commanding the market. It is my understanding that at the present time approximately 20% of the cobalt production in the world is used in these batteries. Already expensive, the price of cobalt threatens to go even higher. Therefore there continues to be a strong incentive to find less expensive alternatives.

With the publication of our results, Michael Thackeray was sent from South Africa to work with me. When he arrived, he said that he wanted to find a cheaper cathode and that he was inserting lithium into magnetite, Fe3O4. I was surprised because spinels were considered to be gem-like materials having little solubility of interstitial cations. However, I had heard Bruno Scrosati of Rome claim the same thing two weeks earlier, so I told Thackeray to repeat the experiment in my laboratory. This he did, and then I realized that the insertion of lithium was converting the spinel to a rock-salt structure. Both structures have a face-centered-cubic oxide-ion array. In the rock-salt structure, cations occupy all the octahedral sites of this array ; in spinels, only half of the octahedral sites are occupied to form a three-dimensional framework with an interconnected interstitial space of face-shared octahedral and tetrahedral sites. In the LiMO2 oxides, the M atoms occupy alternate (111) planes of octahedral sites. In the spinel, the remaining one cation to four oxide ions are ordered in tetrahedral sites of the interstitial space ; with two Li atoms for four oxygen atoms, the layered LiMO2 phase is more stable. Insertion of lithium into Fe3O4 was leaving the spinel framework intact ; the lithium entered octahedral sites of the interstitial space and pushed the tetrahedral-site iron into octahedral sites in a cascade. When I realized what was happening, I told Thackeray to insert lithium into the spinel Li[Mn2]O4 since I knew that in this spinel only Li+ ions would occupy the interstitial space and the [Mn2]O4 framework, though becoming metastable, would remain intact. This he did, and we found a flat open-circuit voltage versus a Lithium anode of 3 V. Removal of lithium gave 4 V. The possibility of an inexpensive cathode transporting Li+ ions in three dimensions stimulated extensive research on this cathode material even though the Li+ ions do not move as rapidly in this three-dimensional framework as they do in the layered oxides.

Unfortunately the manganese spinels do not retain their capacity on repeated cycling in the 4 V range. In the 3 V range, the flat open-circuit voltage reflects a two-phase range ; as the Mn(III) concentration increases with lithium insertion, a cooperative Jahn-Teller deformation from cubic to tetragonal symmetry occurs, and the deformation on repeated cycling tends to crack larger particles so as to cause capacity fade in the 3 V range as well. Recently, Sun Ho Kang came from South Korea to my laboratory in Texas, and we found that this latter problem can be solved by a simple ball-milling procedure that breaks the particles into many small microdomains. However, it looks like the manganese spinels will be restricted to the 3 V range and will face serious competition from other developments.

In order to increase the free interstitial volume for three-dimensional motion of the Li+ ions, I decided to reinvestigate the NASICON structure, but this time as an insertion electrode rather than as an electrolyte. The hexagonal M2(XO4)3 framework is found with several transition-metal atoms M and polyanions having X = Si, P, S, Mo(VI), or W(VI). For example, hexagonal Fe2(SO4)3 has the structure of the NASICON framework. Although the iron atoms are separated by (SO4)2- polyanions, the electronic transport is better than the Li+-ion transport. I was immediately struck by the observation that in this structure, the Fe(III)/Fe(II) redox couple gives 3.6 V versus lithium whereas the Fe2(MoO4)3 and Fe2(WO4)3 frameworks give 3.0 V. Changing the counter cation in the polyanion shifts the working redox energy just as shifting the Li+ ions from tetrahedral to octahedral sites in the [Mn2]O4 spinel framework changes the energy of the Mn(IV)/Mn(III) couple by 1 eV. Moreover, the more acidic polyanions bring the Fe(III)/Fe(II) redox couple into a useful energy range, thereby making an iron oxide a competitive electrode material. This fact was noted by Shigeto Okada of Nippon Telephone and Telegraph, and he was sent to my laboratory to work on stabilization of the hexagonal form of LixFe2(SO4)3. While he was with me, I asked my post doc, Kirakodu Nanjundaswamy, to investigate electrochemically the relative energies of several transition-metal redox couples in the NASICON structure with (SO4)2- and (PO4)3- polyanions. All the redox energies were found to shift by 0.8 eV on changing from (SO4)2- to (PO4)3-. At that time, my student Akshaya Padhi was looking for a thesis topic, so we decided to broaden the study by investigating lithium insertion into several different framework structures containing polyanions. In the course of that study, we found that all the lithium could be extracted from the olivine LiFePO4 and that it gave a constant open-circuit voltage versus Lithium of 3.4 V over most of the compositional range 0 < x < 1 of Li1-xFePO4 due to a small distortion of the FePO4 framework with x = 1. Professor Michel Armand of the University of Montreal recognized immediately that this material would be an excellent match to the polymer Li+-ion electrolyte that he had developed, so he persuaded the Hydro-Quebec Corp. to license our patent. He and Michel Gauthier of Hydro-Quebec then developed a fabrication procedure for achieving the full capacity on repeated charge-discharge cycles at a practical rate. This electrode material promises to be an inexpensive and environmentally friendly replacement for the present Li1-xCo1-yNiyO2 cathode, but other more competitive materials may yet be developed.

BBV : When did you come up with this new oxide ?

JG : In 1994.

BBV : So it is fairly recent. Were you still in Oxford ?

JG : No, I left Oxford in 1986. At that time, a generous donor had given to the University of Texas $8 M for Chairs in Science and Engineering provided the university could match it. In the end, $32 M was raised for a set of chairs, one of which was offered to me. From the endowment, they pay half my salary with enough left over to pay for a secretary and some expendables. Moreover, I didn't have to retire at 67, so I haven't yet ; I am an old tiger enjoying working here.

BBV :So you have a laboratory facility here ?

JG : Yes, we have managed to build up a nice laboratory in Texas. My battery work has been funded by the Robert A. Welch Foundation of Houston, TX. I am most grateful to that organization. They also supported the student with whom I developed the perovskites as solid oxide-ion electrolytes. Keqin Huang came from China to work with me on a solid oxide fuel cell (SOFC) based on the perovskite electrolyte Sr- and Mg-doped LaGaO3, first discovered by Ishihara of Japan. While still at Lincoln Laboratory, I had worked with a mechanical engineer to propose the SOFC as a bottoming cycle for a power plant ; our analysis was based as yttria-stabilized zirconia (YSZ) as the oxide-ion electrolyte. The DOE has since then provided Westinghouse with massive funding to develop the SOFC. Huang and I systematically developed a package of electrodes, buffer layers, and interconnects for a SOFC based on the gallate electrolyte, which we showed gave a competitive performance to SOFCs based on yttria-stabilized zirconia. Westinghouse has now hired Keqin Huang. It is not clear that the gallate electrolyte will be the winner, but the chemical lessons we learned in the process of building our cell will help in the selection of electrode materials and the use of buffer layers. I believe the SOFC technology, though difficult, will find commercial realization in the relatively near future.

But in 1986, while I was moving to Texas, Bednorz and Müller reported the discovery of high-temperature superconductivity in the copper oxides. This discovery brought me back to my study of the unusual physical properties that are encountered at the crossover form localized to itinerant electronic behavior in transition-metal oxides with perovskite-related structures, a study I had been forced to abandon in the early 1970's. Shortly after my arrival in Texas, a letter arrived from a physics professor at the Jilin University in northern China. He had a student interested in the high-pressure work we had done while I was at Lincoln Laboratory, and he wished to have him come to do a Ph.D. dissertation with me ; the degree was to be granted by the Jilin University. I arranged for the student, Jianshi Zhou, to come to the U. S. as a visiting scientist, and I put him to work on the copper-oxide superconductors. Fortunately for me, he continues at Texas in a most fruitful collaboration. We have used high pressure as a variable that allows not only the preparation of materials not accessible at ambient pressures, but also to monitor the change in electronic properties with increasing interatomic interactions in the region of crossover from localized to itinerant electronic behavior. High-temperature superconductivity in the copper oxides and a colossal magnetoresistance in the manganese oxides are found, for example, in mixed-valent systems at this crossover. I have invoked the Virial Theorem of mechanics to show that we can expect a first-order transition at the crossover with a (M-O) equilibrium bond length that is larger for localized than for itinerant electronic behavior. With this idea, we have demonstrated experimentally that where phase separation would occur at too low a temperature for atomic diffusion, it may be accomplished in perovskite-related structures by cooperative atomic displacements. Where these displacements are ordered and static, they give rise to the stabilization of charge-density/spin-density waves (CDW/SDWs). In a mixed-valent system, the cooperative oxide-ion displacements may remain only short-range ordered, in which case the electrons are strongly coupled to bond-length fluctuations that may either segregate a mobile, hole-rich phase or introduce vibronic particles consisting of hybridized electrons and oxygen vibrational modes. We have published a long review on this subject in volume 98 of Structure and Bonding that I edited. Our emphasis on bond-length fluctuations as the fundamental feature of the high-temperature copper-oxide superconductors has not yet been well-received by the physics community, which has concentrated on the importance of the interatomic spin-spin exchange interactions. Given correlation fluctuations that separate spin-rich and hole-rich regions, the spin-spin interactions clearly play a role, but they are associated with bond-length fluctuations that are a general phenomenon associated with the crossover from localized to itinerant electronic behavior. Unusual physical properties are found wherever the fluctuations are not ordered into a static CDW/SDW or do not give rise to a conventional phase separation as a result of atomic diffusion. However, short-range bond-length fluctuations are not detected directly by conventional diffraction techniques. Professor Takeshi Egami of the University of Pennsylvania has developed pair-distribution-function analysis of pulsed-neutron data that is providing a picture of the structure at time scales less than 10-13 seconds ; the data give direct confirmation of the existence of bond-length fluctuations.

AH : They model it on the computer ?

JG : The data analysis is done with the computer, but the pulsed-neutron data that are analyzed provide a picture of the lattice taken within a time that is short relative to a fluctuation. Egami is a careful experimentalist who was willing to develop a technique that could test our hypothesis directly ; his data are quite convincing, and I am very happy that he has been able to provide details of how these fluctuations order themselves into stripes, a detail that our indirect probes could not provide.

AH : So it's the matching of the neutron data with the simulation of the theory that is convincing because the two of them are similar.

JG : Not quite. There is no theoretical simulation of a model. Rather, there is an analysis of the data that provides a direct picture of the positions of the atoms in a short time interval rather than an average position obtained over a long time period. I believe their data on the copper oxides show that the bond-length fluctuations develop more and more long-range order on cooling to the critical temperature for the onset of superconductivity. I believe they order into a travelling CDW/SDW in which the electronic wavefunctions are hybridized with phonons to become heavy electrons, superconductive pairs condensing from the heavy electrons.

AH : So you don't go to many conferences either ?

JG : I go to a variety of conferences in electrochemistry, ceramics, materials science, solid-state chemistry, and physics. I limit myself to those where I am asked to give an invited or plenary lecture. This usually involves several invited talks a year, at least half of which are in Europe.

BBV : Over your career, you seem to have migrated from one discipline to another, finally coming back to where you started.

JG : I wouldn't say it was from one discipline to another, but from one inquiry to another and back again. But perhaps that's the way research goes, in spirals. I have found myself asking one question of a material at one stage and then returning to it to ask another question at a later stage. For example, when I applied the idea of cooperative orbital ordering to LaMnO3 and La0.5Ca0.5MnO3 to explain not only the structure but more fundamentally the anisotropic magnetic order with the formulation of the rules for the sign of the spin-spin superexchange interactions, Wollan and Koehler had also reported no magnetic order in the perovskite LaNiO3. I realized that the Ni(III) ion must have a low-spin configuration, but the lack of a cooperative orbital ordering as well as of magnetic order remained a mystery as everyone assumed the oxides are ionic compounds. At that time we were interested in how the mismatch of the equilibrium bond lengths of the two cations of a perovskite determined distortions of the structure from cubic symmetry or the stabilization of hexagonal polytypes. I went on to consider how the electronic properties would change as the strength of the interatomic spin-spin interactions increased. The metal-metal interactions across shared octahedral-site faces or edges seemed to be an obvious place to look for this change, and indeed TiO and VO are metallic whereas MnO is an antiferromagnetic insulator in which the Mn-O-Mn spin-spin interactions are stronger than the Mn-Mn interactions. When Morin discovered a semiconductor-metal transition in VO2 that is due to the onset of a CDW, I was prepared to think about it. Below the transition temperature Tt ? 67oC, the octahedral-site V(IV) sharing edges along the c-axis pair by forming V-V homopolar bonds. I realized that a change in the translational symmetry can transform a partially filled, narrow band of itinerant electrons into electrons of isolated molecular clusters. Professor Peierls had suggested such a possibility as a one-dimensional exercise in a physics textbook that I have not read, so the change from a one-dimensional narrow band to homopolar bonding between pairs of atoms of the chain is now known as a Peierls distortion. I further noted that MoO2, which is isostructural with VO2 at high temperatures, showed a similar Mo-Mo pairing at lower temperatures, but MoO2 remains metallic. The Mo(IV) ion has an additional d electron that occupies an orbital involved in Mo-O-Mo p bonding, so it dawned on me that covalent hybridization of metal-d and oxygen-p electrons could make the metal-oxygen-metal interactions strong enough to delocalize the electrons. This realization solved for me the mystery of LaNiO3. Paul Raccah had just joined my group from France and needed a project. I told him to prepare LaNiO3 ; he should find it is metallic ! Indeed, it is metallic. This was the first demonstration that the metal-oxygen orbital hybridization in an oxide could be strong enough to de-localize a d-electron configuration as a result of 180o M-O-M interactions. It solved the origin of the metallic conductivity of the sodium-tungsten bronzes, which had been puzzling since its discovery in about 1951. It also led me to map out where the electrons are localized and where they are itinerant in the single-valent oxides with perovskite structure as well as in oxides where metal-metal interactions de-localize the d electrons. At that time, I was unable to prepare the perovskite family LnNiO3, where Ln is a rare-earth atom, as these syntheses require a high oxygen pressure. Later, in Texas, J.-S. Zhou and I were able to show that LaNiO3 contains strong-correlation fluctuations within the band of itinerant electrons. As the size of the Ln3+ ion decreases, narrowing the s* band even further, these strong-correlation fluctuations order into a CDW/SDW below a transition temperature Tt that increases progressively with decreasing size of the Ln3+ ion. We were also able to show that the strong-correlation fluctuations introduce a progressive increase of a Curie-Weiss component in the paramagnetic susceptibility ; the character of the transition from Pauli to Curie-Weiss paramagnetism in the perovskites was addressed experimentally for the first time.

As another example, I had studied with Don Wickham the magnetism of the rock-salt system Ni1-xLixO, 0 £ x £ 0.5, and observed how the Li+ ions order into alternate (111) octahedral-site planes as x approaches x = 0.5. I was later to go back to this layered structure to demonstrate lithium extraction for the cathode of a lithium-ion battery.

I could cite other examples. Already in my first years at Lincoln Laboratory I understood the need to build bridges between physics, chemistry, and engineering in order to be able to design materials that would perform a desired engineering function as well as to explore the fundamental questions of solid-state science. This interdisciplinarity is the hallmark of materials science.

BBV : Do you think of yourself as a physicist, or a solid-state chemist or...

JG : I am a solid-state scientist.

AH : Don't you identify with any of the established categories ?

JG : Well, I would like the chemists to think I am a chemist, but I'm afraid they think I am a physicist. On the other hand, the physicists think I am a chemist.

BBV : That's like the story about Einstein who is a Jew in Germany, but he was a German in Switzerland.

JG : Well, that's life.

BBV : Yes, it's life. But you have been publishing in several journals.

JG : Yes, of course. I am a Fellow of the American Physical Society, and I publish a great deal in the Physical Review and Physical Review Letters. I also was elected as a Chemist to be a Foreign Associate of L'Institut de l'Academie des Sciences de France as I have published extensively in the Journal of Solid-State Chemistry, in the Journal of Electrochemical Society, and in other chemistry journals. I was elected a Fellow of the National Academy of Engineering because I publish in materials science journals such as the Materials Research Bulletin. Thus I identify with all three established categories and am an Associate Editor of several journals.

BBV : I understand you have strong links with the solid-state chemistry community.

JG : Yes, I do. I believe the solid-state chemistry community has been the most appreciative of my attempts to build a bridge between the chemist and the physicist. I have used the experimental strategies of the chemist to explore problems of interest to the solid-state physicist.

BBV : So finally the physicists are accepting you ?

JG : Yes, but sometimes I think a bit reluctantly by some.

AH : And you also publish in Nature.

JG : Yes, I publish in Nature.

BBV : Have you had any links with the people in Grenoble ?

JG : Yes, but no collaborative links aside from a few with workers using their neutron-diffraction facilities. My ties to Grenoble go back to 1954 when I paid a visit to L. Néel, R. Pauthenet, and E. F. Bertaut long before they built up the great facilities there. In 1954, I was able to take a one month leave of absence in addition to my annual vacation, and my wife and I made a splendid tour of Europe. Since I had been working on spinels, I decided to take a side trip from Switzerland to Grenoble to pay my respects to Louis Néel who received a Nobel Prize for his work on ferrimagnetism in these oxides. I also wished to see Erwin Bertaut who had done much pioneering x-ray diffraction on the spinels, perovskites, and garnets ; Pauthenet made the magnetic measurements. I brought to Bertaut my deduction of cooperative orbital ordering in the manganese and copper spinels, and he was delighted to have an explanation of his observations. From that time I have felt a special friendship for Bertaut and for Pauthenet before his too early death. Louis Néel was kind enough to invite me to give a paper at the next International Conference on Magnetism that was held in Grenoble. When I was in England, I went each Spring to Grenoble to referee applications for neutron-diffraction studies there. I have also been invited for 10-day stints to lecture at the University of Grenoble and at the CNRS Crystallography Laboratory that was founded by Bertaut.

BBV : And what are your relations with Professor Paul Hagenmuller ? He is in exactly the same field as you.

JG : My relations with Paul Hagenmuller also go back a long way. The CNRS decided to diversify from Paris some important scientific centers. Grenoble was the first ; Néel, Bertaut, and Pauthenet built up that facility. In the early 1960s Hagenmuller was chosen to develop a solid-state chemistry group in the University of Bordeaux. Already in the early 1960's, before his building was completed, Hagenmuller came to visit me in Lincoln Laboratory. I strongly advised him to build contacts with the physics community. He has had a little difficulty bringing a physics component into his laboratory, but he did develop techniques for physical measurements and his people have interacted with physicists in Paris and Grenoble. In the late 1960s I was able to accept an invitation from him to spend three months in his laboratory ; it was on that occasion that André Cassalot translated my "Metallic Oxides" into the French book Les oxydes des métaux de transition. I have visited, lectured, and collaborated with his people over the years ; and in 1976, Hagenmuller offered me a post in Bordeaux that I declined in favor of the position at Oxford. I received a Docteur honoris causa from the University of Bordeaux in 1967, and I have served as a CNRS advisor to his laboratory as well as to the Bellevue laboratory of Guillaud in Paris. I have had numerous enjoyable contacts with colleagues in France, including an early invitation from Jacques Friedel to spend a year with him in Paris and acting as examiner for many a Thése d'État at several universities. I have had less interaction with Germany.

AH : Why is that ?

JG : I believe it is just a coincidence. Right after World War II, Germany emphasized the rebuilding of their industrial base. Although there was a strong solid-state chemistry tradition in Germany, the chemists like Rabenau and Hoppe were isolated in different universities and were primarily preparative and structural chemists. The Max Planck Institutes did not establish solid-state centers until relatively recently, and they have been slow to recognize the need for interdisciplinarity. However, I have had a little contact with Arndt Simon and Manuel Cardona of the Max Planck Institute in Stuttgart, but there is relatively little overlap between their work and mine. I served with Manuel Cardona as an advisor to the Spanish CSIRO for several years. I also served as an advisor to the Materials Science Center in the University of Groningen when it was first being established under George Sawatzky on the retirement of Franz Jellinek and Cornelius Haas there. I have been better received in Europe than in the U. S.

BBV : But the solid-state community is small here.

JG : Yes, the solid-state chemistry community is only now becoming prominent in America. When I came to Lincoln Laboratory in 1952, the chemistry departments in this country considered that solid-state chemistry was only an exercise in stamp collecting as the community consisted largely of structural chemists. It was only in a few industrial interdisciplinary laboratories like the Bell Telephone Laboratories and IBM that the solid-state chemists were interacting with engineers and physicists. However, even there they served the physicists and engineers by providing them with single crystals. When I took charge of the small ceramics facility at Lincoln Laboratory, I said to myself that I wanted to make the physicist serve the chemist rather than the other way around, so I said to my people, "We have got to be the dog, not the tail ; we will let the physicists be the tail, not the other way around." I suppose it was that attitude that made Oxford accept me as a chemist.

AH : It seems that you have had quite a lot of contact with the Chinese and Japanese.

JG : I see you have done a lot of homework.

AH : We can see Chinese and Japanese names on your publications in the last five years.

JG : You should also see several Indian names. In my years in Texas I have had post doctoral and doctoral students from China and India as well as visiting scientists from Korea and Japan. I have already told you about J.-S. Zhou and Keqin Huang. My contacts with Japan also go back a long way. My first trip to Japan was in 1961. I had been invited there the year before by Nagamiya, but I could not go then. Junjiro Kanamori was his student, and he went to work with Jacques Friedel when I couldn't get leave to spend a year in Paris. Nagamiya and Kanamori were interested in my rules for the sign of the superexchange interactions and my prediction of cooperative orbital ordering in LaMnO3. There were other Japanese working on ferrites who came to visit me before 1961. One was Shuichi Iida of the University of Tokyo. It was his assistant, Koichi Mizushima, who came to me in Oxford and did the initial experiments on the Li1-xCoO2 and Li1-xNiO2 battery cathodes.

During my visit to Japan in 1961, Pauthenet of Grenoble and I were invited by Eiji Hirahara to lecture in Sendai ; I exchanged Christmas greetings with Hirahara every year until his death and interacted with him on the MnP-MnAs system. On that occasion I was also invited to lecture in Sapporo where I remember the pleasure of eating corn on the cob sold by a street vendor. In 1976, I was invited by H. Watanabe of Sendai to be a three-month visiting scholar of the Japanese Academy of Science, but I was only able to stay one month because I had to take up my new post in Oxford that autumn. I have had quite a few invitations to visit Japan, and I have enjoyed interacting with the scientists there. The Japanese have made a wonderful contribution to my fields of interest, and I have been a member of the Japanese Physical Society since about 1954.

The Japanese were interested in my work on magnetism in the early days and our work overlapped quite a bit. For example, Chikazumi was interested in my analysis of the factors that determine the shape of a B-H hysteresis loop, our discovery of cross-tie domain walls in thin films, and the damping factors that control the speed of domain-wall switching during a magnetization reversal ; he was in the process of writing a magnetism text book. Tom Kaplan, who was working with me in the late 1950's and early 1960's, discovered theoretically the possibility of spiral-spin configurations as a result of competitive exchange interactions ; the same theoretical discovery was made simultaneously in Japan and France, each from an analysis of the magnetic order in a different compound. We had a hard time convincing the theorists that the period of a spiral-spin configuration need not be commensurate with the crystal lattice. Tom Kaplan was interested in calculating the ground-state configuration ; as an experimentalist E. F. Bertaut of Grenoble was interested in deciphering the complex spin configurations revealed by his neutron-diffraction experiments. Both independently came up with the same mathematical formalism. There are moments when the time is ripe for certain ideas to emerge, and people working in different countries come up with similar solutions at the same time. Who gets the credit is important for the individual scientist, but it doesn't really matter for the progress of science.

More recently, the Japanese have been actively studying high-temperature superconductivity in the copper oxides and the colossal magnetoresistance in the manganese oxides. Professor Tokura has a large group growing single crystals, and we have made measurements on a few of his crystals. Mikio Takano, now a professor at the University of Kyoto, collaborated with me on the demonstration of a pressure-induced high-spin to low-spin transition at the Fe(IV) ions of CaFeO3.

AH : So the Japanese with whom you had contact were all in the university world ; it wasn't SONY or another corporation ?

JG : They were, for the most part, all in the university world or a research institute. But of course, SONY commercialized my work on cathodes for a rechargeable lithium-ion battery ; it was the basis of my selection as a Laureate of the 2001 Japan Prize. Because of this work, the Nippon Telephone and Telegraph Company sent Shigeto Okada to me and SONY sent me Yamada for a year.

AH : You allowed them to do that ?

JG : I have always been happy to receive good people who are funded by a home laboratory to which they will return. I don't have many sources of funding. David Nelson at the National Science Foundation has provided support for a post doc and a student and the Robert A. Welch Foundation has provided support for two students. I have had a little miscellaneous money from time to time that has helped me get through some lean times.

BBV : Does it cover equipment as well as students ?

JG : Not permanent equipment, but expendables.

BBV : You said you were interested in developing materials that would perform an engineering function. Do you go after research for industrial development ?

JG : No, I don't do industrial development ; but I do long-range targeted research. For example, when we developed LiFePO4 as a cathode material, we patented it and licensed it to the Hydro-Quebec Corporation. The people in Canada did the industrial development of how to fabricate a commercially viable material. Once I have identified a material that will perform a desired engineering function, I leave it to industry to commercialize it.

BBV : But if you have a problem-solving approach rather than an end-product approach, then the problem that you solve might be used for several end products rather than one. Which approach would you recommend for research productivity ?

JG : Research is productive not only when it produces a commercially viable end product, but also when it increases our understanding. Let me make a distinction between long-term targeted research and fundamental research that uncovers new phenomena or provides the understanding needed to know how to go about designing or searching for a new material for a specific engineering function. Examples of my targeted research efforts are the development of the ferrite memory core, of solid electrolytes, of battery cathodes, of materials for a solid oxide fuel cell, of wavelength-selective films for heating with solar energy, of a sole material for an amplifier tube that emits nearly 100 secondary electrons for every primary electron that strikes it, or our unsuccessful attempt to photo-electrolyze water with sunlight in one step rather than two. Yes, in the process of solving or evaluating these long-range targeted-research problems, we did more than obtain an end product ; we also learned a great deal about materials that not only increased our fundamental understanding, but also was to prove useful for solving another targeted-research problem. For example, our demonstration that a thin buffer layer can be used to prevent a chemical reaction between the electrolyte and the anode of a solid oxide fuel cell immediately suggests fabrication of a bilayer oxygen-permeable membrane for partial oxidation reactions. However, targeted research needs to be driven by a well-defined engineering need and a careful description of the engineering constraints expressed as a material "figure of merit" or some other set of criteria. If the engineer does not have a material in hand that can do his job, he can only turn to long-term targeted research to indicate the feasibility of the problem if not a solution to it. In my view, long-term targeted research is well served when there is a balance of fundamental research that can bring the discoveries needed to resurrect abandoned projects or to inspire new engineering concepts. I try to maintain such a balance in my research group. It would be unfair to ask a student to do a Ph.D. thesis involving an end product that is already under intensive development by industry.

I would also distinguish between the extrinsic and intrinsic properties of materials. For the most part, I have been interested in the intrinsic properties of a material whereas the industrial scientist is often concerned with how to optimize performance by changing its extrinsic properties such as shape, morphology, single-crystal versus polycrystal, or doping level. However, we did stabilize the capacity of the manganese-spinel cathodes by ball milling to create microdomains in our particles. Nevertheless, I am not a typical material scientist concerned with problems of fabrication and manufacture of materials that have already been identified as suitable for a particular end use. That's why I consider myself a solid-state scientist more than a materials scientist.

AH : But isn't the market the ultimate driver ?

JG : Engineering problems are driven by the market. But as a scientist, curiosity is also a driver ; one wants to understand the physical processes that govern the material properties we observe and exploit. Solving a problem in materials engineering may require addressing fundamental scientific questions. These are the problems that I prefer. For example, the market would like an electric car that performs as well as the cars we drive today. An engineering solution would be a direct methanol-air fuel cell. It would make possible an electric car powered by a liquid fuel just as the present-day internal-combustion engine is powered by gasoline. Conversion of the chemical energy in methanol to electric power in an electrochemical cell is a well-defined engineering problem, and the engineering constraints are defined by the performance of today's automobiles. However, to achieve adequate power requires identification of a solid H+-ion electrolyte and probably a better methanol-oxidation catalyst as well. Identification of materials that can perform these functions requires understanding of the processes that govern the phenomena of interest. Until these materials problems are solved, there is no point in proceeding with the engineering.

BBV : It seems to me that when you addressed the problem of an electric car in a 1978 paper, you didn't separate the electrolyte and electrode problems. You appeared to address both problems without separating them.

JG : The electrode and electrolyte problems are clearly separable ; each performs a different function. The anode must be an electronic conductor that catalyzes the oxidation of methanol, CH3OH, to carbon dioxide, CO2, and H+ ions whereas the electrolyte must be an electronic insulator that conducts protons. The cathode must be an electronic conductor that reduces the dioxygen molecule O2 to two oxide ions that combine with the H+ ions coming from the anode on the other side of the electrolyte. Carbon dioxide is the exhaust product at the anode, pure water is the exhaust product at the cathode. The entire package of electrodes and electrolyte must be considered together because the chemical potentials of the electrodes must be matched to the stability window of the electrolyte. With an H+-ion electrolyte, the cathode must be porous to allow escape of the water produced at the electrode-electrolyte interface. In a solid oxide fuel cell, an oxide-ion electrolyte allows use of a mixed oxide-ion/electronic conductor since there is no exhaust product emanating from the cathode/electrolyte interface in this case. Nevertheless, the chemical potentials of the electrodes must still lie within the stability window of the electrolyte.

BBV : Do you think you have contributed more to electrodes or to electrolytes ?

JG : I have contributed to both, but more to electrodes. My contribution to the lithium-ion battery has been the cathode, for example. I have made no contribution to either the liquid or the polymer electrolytes used in these rechargeable batteries. I have pioneered the use of a perovskite for the solid O2—ion electrolyte of a solid oxide fuel cell, but my more fundamental contribution was my early work on metallic perovskites that led the way to the use of these oxides as cathodes of the solid oxide fuel cell ; they include the purely metallic manganese oxides and the mixed oxide-ion/electronic conductors. All of the early fundamental work on metallic perovskites and my later work on perovskite oxide-ion electrolytes have provided a basis for selecting cathode and electrolyte materials, but the perovskite electrolyte faces stiff competition from oxides with the fluorite structure.

BBV : And what is your opinion about a specialized journal for the community of researchers working on solid-state ionics ?

JG : I have not been a strong advocate of specialized journals. On the other hand, solid-state ionics has become an important sub-field of electrochemistry, and I can understand the need for rapid publication of developmental results in a specialized journal. I would expect the more fundamental studies to be published in non-specialized journals. On the other hand, Physical Review and the Journal of the American Chemical Society cover so much territory that there was a need to create a Journal of Solid-state Chemistry. This journal has been quite successful, but I worry a bit that its emphasis may become too much on the preparation of new compounds and their structural characterization as new specialized journals are beginning to pull away papers on targeted research and the physics journals pull away the papers having a strong physics component such as those on high-temperature superconductivity and the colossal magnetoresistance.

When I went to Hawaii to receive the Olin Palladium Medal from The Electrochemical Society, I was struck by the tremendous impact of solid-state ionics on that society and on solid-state chemistry. The fact that people are making a great deal of money with the lithium-ion batteries and that the fuel cells are showing more commercial promise has brought financial support into the field. I expect the LiFePO4 cathode will stimulate the field further. It is cheap and environmentally benign, so it may become competitive in large batteries. I can't claim to have designed it ; but I did have an idea where to go fishing. In any case, the field of solid-state ionics is growing, and journals that cater to the field will undoubtedly prosper.

BBV : One more factual question. You have had a lot of students over the years. Did you teach ? Did you have to teach ? What difficulties did you have with teaching ?

JG : Lincoln Laboratory was a Research & Development facility separate from the MIT campus. During my 24 years there, I had only one Masters and two Ph.D. students and I only gave a short series of lectures, never a formal course.

The system at Oxford is totally different from that of a U. S. university. Students come up to Oxford to read Chemistry with two years of Advanced Level science courses that are equivalent roughly to the first two years in a U. S. college. Chemistry students were selected by each College by the Dons of that College who coached them for three years for a career-making final examination. The Inorganic Chemistry Laboratory provided a mandatory Practical Course and a series of 8-lecture courses that were optional, but generally provided material essential for the big final examination. I gave lectures on solid-state topics that were not necessarily covered in their finals, so the half-life of the attendance in my classes tended to be fairly short. After the final, the students did a fourth year of research for their undergraduate degree. My principal contribution to undergraduate teaching was probably the supervision I gave to those who chose to do this research year with me.

At Texas I am required to teach two graduate courses a year. I have also taught undergraduate courses in Mechanical Engineering and Electrical Engineering. I prefer teaching the graduate courses. Of course, my hope is that considerable learning occurs in the course of completing a Ph.D. with me. Those who have absorbed the most are a few excellent students and the better post docs.

AH : I would like to run with the instrument ball for a bit. How do you see the development of instrumentation having an impact on your work ?

JG : That 's a big question.

AH : Maybe you could start by saying what was available in 1951 when you started.

JG : Let me restrict myself to the field of transition-metal oxides. In 1951, ceramic materials were made mostly with high-temperature powder-metallurgy techniques or hydrothermal synthesis. The use of organometallic precursors to lower firing temperatures was a novel idea. Physicists wanted single crystals. The growth of single-crystal magnetite was a major undertaking and achievement. Zone refining of germanium to achieve single crystals of high purity was being developed ; oxide crystals were grown primarily by the Czochralski technique of pulling a seed crystal from the melt. Crystal growth from a flux was just being developed as an art. Now we have an image furnace with which we are able to grow oxygen-stoichiometric oxide crystals of high purity. In 1951, chemical characterization rarely included the analysis of oxygen stoichiometry ; thermal-analysis instruments were not commercially available, and mass spectrometers were used. High-pressure synthesis was carried out in a few laboratories, but techniques for applying high oxygen pressures were not yet developed. Thin films were prepared by primitive sputtering machines. Since those days, soft chemistry is widely used for synthesis and more complete chemical characterization of ceramic materials has become normative. Films are now deposited by a variety of techniques, many of which were not then available. Laser deposition is an example.

In 1951, the electron microscope did not have the high resolution that is available today. The first direct observation of a dislocation was made at that time. The principal tool for structure determination was X-ray diffraction, but analysis of the data was laborious. The first observation of antiferromagnetic order by neutron diffraction was made at that time. Neutron-diffraction and scattering measurements have now become sophisticated and fundamental tools in solid-state science. The advent of synchrotron radiation and pulsed neutron techniques have enabled direct observation of structure at short time scales, which is opening a whole new field of study.

Various spectroscopies were available in 1951, but photoelectron spectroscopy had not yet been developed and nuclear magnetic resonance was in its infancy. Mössbauer spectroscopy and the laser had not yet been imagined. A principal tool at that time was electron paramagnetic resonance. Impedance spectroscopy for measuring the ionic conductivity of electrolytes was not commercially available.

The superconducting magnet and the SQUID magnetometer did not exist. To obtain a magnetizing field of 50 kOe was a big-science project. The vibrating-sample magnetometer was developed at Lincoln Laboratory by Simon Foner in the late 1950s, and Don Smith of my group developed a vibrating-coil magnetometer that allowed us to do magnetic measurements under high pressure. However, the measurement of physical properties under high pressure is still restricted to a few laboratories.

The development of affordable, powerful computers for data collection and analysis has transformed the accuracy and speed with which measurements can be taken. It has quite revolutionized the experimental laboratory.

AH : So what was the infrastructure of the Lincoln Laboratory, of Oxford, and here in Texas ?

JG : The ceramics laboratory that I inherited at Lincoln Laboratory had high-temperature furnaces, a hand press, a hood, a powder x-ray diffractometer, and chemical benches. We were in the Digital Computer Division ; the Solid-state Division was much better equipped, but our access to their facilities was essentially non-existent as each person in that division had an agenda of their own. However, their mass spectrometer was a service facility to which we had access. We made routine transport measurements on the samples we prepared and characterized structurally. I developed a good working relationship with Jim Kafalas who had developed a high-pressure belt apparatus and was looking for something interesting to do with it. With him, John Longo and I demonstrated the relationship between bond-length mismatch in the perovskites and the hexagonal polytypes. Kafalas also developed high-pressure equipment for magnetic measurements with the vibrating-coil magnetometer. We used pressure to change from one polytype to another and to transform from high-spin to low-spin magnetic configurations. I came to appreciate the pressure variable as an extremely useful research tool. We also acquired sputtering equipment for the preparation of wavelength-selective films and for our MgO-Au composite film. At Lincoln, I relied primarily on developing chemical strategies that could provide important information with the measurement facilities at my disposal. I suppose that is why Oxford considered me as a solid-state chemist.

At Oxford, there was little money for equipment in the Inorganic Chemistry Laboratory. I was not given any significant start-up funding, so I relied on the availability of x-ray diffraction, facilities for chemical analysis, a glass-blowing shop and an electronics shop. I acquired furnaces for my own synthesis needs, the means to make impedance spectroscopy and routine electrochemical measurements as well as the optical equipment needed to study photo-electrolysis. The laboratory also had photoelectron spectroscopy and nuclear magnetic resonance, and I did some collaborations with those working with these instruments. Outdated equipment for electron paramagnetic resonance was put into use in the one systematic catalytic study I made on the phosphopolymolybdates. One group in the laboratory was given a second-hand vibrating-sample magnetometer that proved more frustrating than useful. At Oxford, I concentrated on ionic transport, battery cathodes, and photo-electrolysis ; I did relatively little work on the transition from localized to itinerant electronic behavior except to show that hybridization of the d electrons of a transition-metal atom with 6s2 core electrons of a counter cation could cause a localized electronic configuration to become delocalized.

AH : You just didn't have the infrastructure for magnetic measurements ? You couldn't have gone off and used magnetometers elsewhere in the university ?

JG : I suppose I could have developed a collaboration with someone in the Clarendon, but I was busy with another agenda.

AH : Were you a member of a College ?

JG : Yes, St. Catherine's.

AH : And were you able to build interdisciplinary connections through your college ?

JG : It should have been possible in principle, but it didn't turn out to be practical. When I arrived at the University of Texas at Austin, I was given $300 K as a start-up package and an empty room. Professor Hugo Steinfink had an x-ray diffraction laboratory that he has generously shared. He also had a high-pressure belt apparatus in disrepair that was a copy of the one developed by Kafalas at Lincoln Laboratory. I also had access to electron microscopes. With the help of post docs, I built up first my chemical facilities, including thermal analysis, impedance spectroscopy, a dry box, atomic absorption spectroscopy, an arbin battery tester, and equipment for routine electrochemical measurements. We do our own chemical analysis. We later added a SQUID magnetometer and an infrared image furnace for growing single crystals. J.-S. Zhou has developed measurement of transport and magnetic properties under pressure as well as specific-heat and thermal-conductivity measurements. Keqin Huang also developed apparatus for oxygen-permeation measurements. With our own synthetic facilities, we can develop our experimental strategies without relying on others. If you rely on getting crystals or samples from someone else, they have already done all the routine measurements on it. With only a special measurement technique, you must rely on collaborations. If you want to understand how physical properties vary with changing chemistry, you have to be able to make your own materials. I have always thought that was critical.

BBV : You never rely on others ?

JG : Occasionally we have received crystals that we could not prepare when others wanted us to collaborate by making measurements under pressure ; but for the most part we rely on our own samples designed to carry out a particular experimental strategy. People have also come to me for help in the interpretation of their data.

BBV : When you were at Oxford, did you have contact with other universities in England and Europe ?

JG : Yes. I went to Scotland to examine undergraduates. I also examined D. Phil. and Thèse d'Etat candidates in universities of England and France. I interacted some with Brian Steele of Imperial College, London, and his colleagues ; they were interested in the solid oxide fuel cell. At Cambridge, Sir Nevil Mott was interested in the transition from localized to itinerant electronic behavior, and Greenwood at Leeds was a solid-state chemist who did Mössbauer spectroscopy. At AERE Harwell, I collaborated in a European project with a Danish group on the development of lithium-ion batteries and an unsuccessful attempt to realize a methanol-air fuel cell. In France, the people in Montpellier were interested to interact on the subject of solid proton conductors, and I wrote a long review on iron oxides with Charles Gleitzer of Nancy. Hagenmuller sent me a young man from Bordeaux to work with me for over a year, and Jean Rouxel of Nantes sent me someone for six months. Pepe Fontcuberta came for a summer from Barcelona, and I had some interactions with electrochemists in Madrid. I was also asked to give a series of lectures at different universities in Norway on one occasion and in Germany on another. Emanuel Kaldish of the ETH in Switzerland arranged conferences for young people of the underdeveloped countries in Erice in Sicily, in New Delhi in India, in Cairo and Alexandria in Egypt. I also went to India, a country I have visited several times, as the Raman visiting professor.

BBV : And having this experience in Europe and the United States, do you have any idea why materials science generally never started in Europe as here although they have had a great tradition of solid-state chemistry ?

JG : The brief answer is our mission oriented defense and space efforts. England had a strong tradition in metallurgy and solid-state physics out of which grew a magnificent contribution to physical metallurgy. France and Holland had a strong tradition in magnetism out of which grew, secretly during World War II, the development of the ferrospinels that proved critical not only for the memory of the digital computer, but also for microwave devices. In this country, the development of the transistor was also seminal. Work on the nuclear bomb in Los Alamos and on radar at the Radiation Laboratory of MIT during the 1940s alerted the military people to the power of interdisciplinary research ; faced with the challenges of the Cold War, they encouraged this type of research in places like the Bell Telephone Laboratories, the Lawrence Livermore Laboratories, and the MIT Lincoln Laboratory. The military people also encouraged NSF to establish interdisciplinary materials laboratories in several of our universities. Bell Telephone had a monopoly in the early days, which enabled it to plough back its excess profits into research. In the 1950s and 1960s, the Bell Telephone Laboratories were the dominant player in the development of materials science both because of the changing nature of their business and because of large government contracts to develop military and space hardware. The development of fiber optics is an example of how their mission as a communications company kept them involved with materials problems. With the completion of the SAGE system at Lincoln Laboratory, IBM was chosen to manufacture the digital computers for it. The government allowed IBM to add 10% to the cost for product improvement ; they used these funds to build their Yorktown Heights research facility. Kennedy's decision to send a man to the moon within a decade added another set of materials problems that needed to be solved. Moreover, polymers were proving to be a great commercial success. It was the creation of mission-oriented laboratories and the technologies they spawned that challenged the traditional academic disciplines. Technical knowledge was being created rapidly outside of academia ; the traditional Metallurgy and Electrical Engineering departments were forced to expand their definition so as to include the new technologies and to prepare graduates for careers in these new types of laboratories. France under De Gaulle chose to become independent in military and space hardware, so a strong materials science effort was initiated in France under his leadership.

Also, during and following World War II, companies like DuPont de Nemours and Corning Glass had lively interdisciplinary research groups that produced numerous new products. It is unfortunate that most of these industrial facilities are now starved of corporate funds and must compete for government funding of their long-range targeted research.

The chemistry departments in the U. S. and Great Britain have been slow to build up solid-state chemistry as an interdisciplinary subject ; the inorganic chemistry community has been dominated by organometallic chemistry. The solid-state chemists have been incorporated into the materials science and engineering programs in the U. S. Only now as the engineers look for components at the molecular level are the chemistry departments becoming more involved. France, Holland, and Japan have recognized the importance of solid-state chemistry, but of course their development came only after a period of reconstruction following World War II. Russia has emphasized materials science as it, too, had military and space missions. Germany had a longer period of reconstruction, and their mission-oriented laboratories have all been industrial. The Max Planck Institutes are not mission oriented in the same way as the Department of Defense and Energy in this country, so materials science as we know it here has developed slowly in Germany.

Identity with a clear mission is important not only for the development of materials science, but also for the vitality of an interdisciplinary laboratory. For example, the MIT Lincoln Laboratory was the key player in the development of the digital computer during the 1950s. That success reflected a clear mission. When that mission was completed, the leadership lost its vision for further development of the digital computer, and therefore its most talented experienced staff in this field went elsewhere. By the end of the decade, it was clear that the future of the computer lay in making all the components smaller. Microelectronics was the next logical step. However, the Head of Lincoln Laboratory and the MIT administration did not wish to compete with industry in this next phase, so Ken Olsen took a group of computer engineers from the laboratory and founded the Digital Equipment Corporation. Others were given opportunities for leadership in several corporations. A few months later, a group of engineers who stayed with the laboratory had built a small computer that would be affordable by a single research unit. Wes Clark brought it down to the National Institute of Health where he solved in one afternoon a problem they had been working on for months. It was the first demonstration of the efficacy of a small computer. When he returned triumphant the next day, the Head of Lincoln Laboratory announced, "There will be no wet scientists in this laboratory." Consequently this innovative and motivated group left the laboratory.

On the other hand, there is also a strong cultural component. When I went to England, I found that members of the Inorganic Chemistry Laboratory downgraded targeted research ; "pure" research was only curiosity driven ! Moreover, I was astonished when a leader of a chemical industry told me they were hiring few people with a D. Phil degree because these people were only interested in "pure" research. This dichotomy between curiosity-driven and targeted research in a country where class distinctions are so important has, in my view, been a great impediment to Britain's development of materials science as we know it. In France, on the other hand, the Grandes Ecoles have been developing engineers for leadership posts. A British colleague acting as Director of the Institut Laue Langevin (ILL) laboratory in Grenoble told me that the British equipment salesmen knew everything about sales, but little about the performance of the equipment they were selling whereas the French salesmen were good engineers and could answer the specific questions posed by the experimental customer. France's delay in developing a strong presence in the field of materials science was largely due to the period of recuperation following World War II. Establishing the CNRS laboratories gave science a strong boost. However, the CNRS laboratories, like the Max Planck Institutes in Germany, tend to be built around an individual with a specific technique or area of specialization. They are rarely mission oriented unless they receive supplemental financial support from industry or a mission-oriented government agency. Nevertheless, they do build into the university structure the means to develop interdisciplinarity and thus to bid for targeted-research funds. Without the infrastructure of research scientists and equipment that the CNRS provides, the individual university professor with four or five students is isolated and generally unable to compete with larger groups in targeted research unless it is quite long-range.

BBV : Has it been possible for the European to do away with national identity ?

JG : There are now numerous large-science projects that are European rather than national, and science itself has an international character. However, cultural differences and national identities persist. The ILL in Grenoble, for example, is jointly supported by England, France, and Germany. The Director is rotated every three years between the three countries. Nevertheless, the groups from the different countries each bring a different style, sometimes to the irritation of one another. Also, Brussels funds projects that are required to be multinational. I had one with the French and Danes on batteries and had just negotiated another on fuel cells with the French and Germans when I returned to the U. S. These projects tend to be strategic, long-range, targeted research addressing fundamental materials problems. With the globalization of industry and a NATO alliance, the national barriers to cooperation are breaking down, but a national identity and competition for a market-share will accompany their European identity.

AH : You have just outlined the situation in the U. S., Britain, France, and Germany. Do you have any sense of how Japan fits into this process, or is that asking too much ?

JG : No. Japan has done a remarkable job in the area of materials science. The Japanese have not had a military mission, but they have realized their need to compete for external, high-technology markets. Therefore, they have set up mission-oriented government laboratories in support of their industries. They have also established interdisciplinary laboratories in association with universities ; these undertake the longer-range kinds of research that interests me. The large Tsukaba consortium is an interesting experiment that is well suited to the Japanese style. Japan is a homogenous society with a strong national identity ; its people strive to prove themselves after their defeat in World War II. They have built up an excellent cadre of scientists and engineers that is well supported with a sophisticated infrastructure of equipment ; and they make excellent measurements and theory. In my areas of interest, the Japanese are leading competitors and contributors. I am also happy that there are influential voices in Japan that are aware of our need to find a balance between nature's bounty and its exploitation by man.

AH : Now you are emphasizing the funding for equipment and the design of new instruments. I had the impression when you were talking about your own experience that you were de-emphasizing the role of instrumentation.

JG : I didn't mean to leave that impression. I emphasized the importance of being able to make your own materials if you wish to develop a chemical experimental strategy in materials science. I have used, for the most part, quite standard physical measurements because of the limitations of my own situation. However, where it was possible for me to develop instrumentation, I have supported it. Our most innovative instrumental developments have been in the area of high pressure. With Jim Kafalas, I used high-pressure synthesis of metastable phases and the measurement of magnetic properties under high pressure. Unfortunately my program at Lincoln Laboratory was terminated before I could fully exploit our facility. However, we did enough to attract J.-S. Zhou to Texas, and with him I have used pressure not only for the synthesis of metastable phases, but also as a variable to probe new electronic states in solids and transitions into or out of these states without changing the chemistry. Measurements made at the major national facilities are followed carefully ; they guide our strategies. I have already mentioned a number of these techniques.

AH : Can you point to instrumentation that has actually changed your trajectory, your research strategy, because you can now do things that you couldn't do before ?

JG : My research trajectory has been determined by questions I wanted to answer or by engineering challenges ; but of course the strategies we choose depend not only on our questions, but also on the facilities at our disposal. The advent of neutron diffraction, which allowed precise observation of the positions of lighter atoms such as oxygen as well as of ordered spin configurations, has certainly motivated much of my research even if the predictions made were to be confirmed experimentally by those with access to neutron diffraction. Similarly, the direct observation with high-resolution electron microscopy of extended defects such as shear planes and charge-density waves stimulated my research and clarified my view of solids. Access to high pressures has also allowed me to develop experimental strategies that have proven fruitful in my studies of phase transitions, especially high-spin to low-spin transitions and the crossover from localized to itinerant electronic behavior. I have made occasional use of Mössbauer spectroscopy. The development of the vibrating-sample, the vibrating-coil, and the SQUID magnetometer have played a central role. I should also mention that superconducting magnets have given us access to 50 kOe magnetizing fields that were, in 1951, restricted to a few centers. I have made less use of the laser, but the ability to deposit high quality films has been used from time to time. The ability to grow high-quality oxide single crystals with the IR image furnace has also shaped my strategies. Of course, we should not overlook the influence of computers on the automation of our experiments. The commercial availability of such instruments as Thermal Analysis or the Solartron have also enabled me to move into fields without having to build my own apparatus. Photoelectron spectroscopy is a technique that I have happily used whenever I could get access to it with a collaborative partner. The opportunity to find collaborators can be a great determinant to one's research trajectory.

AH : You have just told us about Japan. Do your Chinese colleagues give you any sense of what is going on in China ? Have you been to China ?

JG : Yes, I had the opportunity to make a fairly extensive visit to China a few years ago, and my colleague J.-S. Zhou keeps contacts there. The first observation is that China is changing rapidly. Under Mao Zedong the lid was on everything. Under Deng, people were allowed to make money, but politics remained tightly controlled. Under the present regime, people are more free to think as well as to make money, and the energies and imagination of the people has been unleashed, but within a nationalistic view and still restricted framework. The people value education. Western high-technology industries have moved their production facilities to China to have access to skilled, cheap labor. As a result, they are transferring manufacturing technical and managerial skills to China. The present government has decided it needs to compete with the world in high technology, so it is in the process of establishing research centers that are well-equipped with the latest tools. They have a big pool of educated talent, and they are beginning to bring back from the West with big salaries those they believe can lead their scientific as well as their technical development. China wishes to emerge as one of the leading countries in the science and technology arena. It is too early to tell how their investment will pay off. For the last 50 years, India has poured a substantial percentage of their gross national product into science and into technical education, but the return to the country has not been commensurate with the investment despite the emergence of excellent Indian scientists, many of whom work in the West. The political culture is extremely important.

AH : Have you seen the laboratories in China ?

JG : I was in China before the decisions were made to put a big investment into instrumentation in science research laboratories. I had no access to their military laboratories ; these were undoubtedly equipped first. At the time of my visit, researchers in the universities were not well equipped. Now the computer network and the cell telephones are as prevalent in the big cities as anywhere in the West.

In the last 30 years there has been a steady increase in the number of Asian students that come to this country for higher education. Many of them stay and make a wonderful contribution to our high-technology corporations and our schools. When I was younger, I was moved to wonder how the U. S. could best help the underdeveloped world to come into the technological age. I thought then we should be helping to set up research laboratories there, which is why I considered going to Iran in 1975. I have now come to realize that providing the opportunity to come to our graduate schools and the transfer of manufacturing facilities to their countries is a much more efficient method of providing help. But the political culture has to be right. It breaks your heart to see the conditions under which so many people struggle for life. Why hasn't Mexico taken off and done something more ? Why does a country like Argentina have 30% unemployment today ? It's sad. It shouldn't be. It shouldn't be like that.

Fin de l'enregistrement.

Pour citer l'entretien :

« Entretien avec John B. Goodenough », par Bernadette Bensaude et Arne Hessenbruch, mai 2001, Sciences : histoire orale, /spip.php ?article28.

Pour citer l'entretien :

« Entretien avec John B. Goodenough », par Bernadette Bensaude-Vincent et Arne Hessenbruch, mai 2001, Sciences : histoire orale, https://sho.spip.espci.fr/spip.php?article28.

Lieu : University of Texas, Austin (USA).

Support : enregistrement disque.

Transcription : Bernadette Bensaude-Vincent et Arne Hessenbruch.

Édition en ligne : Pierre Teissier