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HIRAO Kazuyuki, 2002-08-29

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Kazuyuki Hirao.

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Pour citer l’entretien :

« Entretien avec Kazuyuki Hirao », par Bernadette Bensaude-Vincent et Hervé Arribart, 29 aout 2002 Sciences : histoire orale, https://sho.spip.espci.fr/spip.php?article125.

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Entretien avec Kazuyuki Hirao, par Bernadette Bensaude-Vincent et Hervé Arribart, 29 aout 2002

Lieu : Department of Materials Chemistry, Kyoto University

Support : enregistrement non précisé

Transcription : Bernadette Bensaude-Vincent et Hervé Arribart

Edition en ligne : Sophie Jourdin

HERVE ARRIBART (HA) : In which discipline did you take your degree and your Ph.D.?

KAZUYUKI HIRAO (KH) : I was trained in Inorganic Chemistry.

BERNADETTE BENSAUDE-VINCENT (BBV) : Why did you decide to go into Glass Science ?

KH : Well, you know, the Chemistry Department of Kyoto University is very old, 100 years old. When I had to select a laboratory, I was interested in inorganic chemistry. I belonged to the Chemistry Department but only one division of chemistry was Glass or Ceramics related to inorganic chemistry.

BBV : Did you publish books in inorganic chemistry ?

KH : Yes, I published two textbooks on Inorganic Chemistry intended for undergraduates. One of the textbooks was translated but another one I wrote myself in Japanese.

BBV : Do you have to teach inorganic chemistry ?

KH : Yes at the undergraduate level.

BBV : And do you have to teach a course in Materials Science ?

KH : Yes I have 3 courses a week : one of them is Glass Science, the second is Advanced Materials, and the 3rd one is Inorganic Chemistry. Inorganic Chemistry for undergraduate students, Glass science and Advanced Materials for graduate students.

BBV : There is no department of Materials Science at Kyoto University ?

KH : Materials Science partly belongs to chemistry. My department is called Department of Materials Chemistry. But Materials also belongs to Metallurgy. They have a department of Materials Science which is totally separated from us. We have no common class between Materials Science for chemists and Materials Science for metallurgy. We have to collaborate in the future. The Department of Materials Science also belongs to the Department of Mechanics. Chemistry and Mechanics are totally different. Polymer Chemistry is also separated. We still have to build up the new class of Materials Science. In Japanese universities, it is not usual to have interdisciplinary Materials Centers. It is usually divided. It is not good for research. Because equipment is shared.

HA : What kind of instruments ?

KH : TEM, SEM, X Ray, spectroscopy. At least in nanotechnology we ignore the boundaries between polymer science, metals, ceramics and glass. It will be possible to develop the new materials perspective.

BBV : Do you think that this traditional university system prevents you from doing Materials Science ?

KH : It is difficult to change. If you want to change anything, you will have to obtain agreements from all the professors in our departments. University professors are very conservative.

HA : Still, Professor Soga did endeavor to change the system while he was here.

KH : Yes, but in Japan if one single professor is against the change, then there will be no change at all. We don’t usually have a majority decision making system.

BBV : Are the students more attracted by Materials Science in general or by Chemistry and Physics ?

KH : The entrance examination is about Industrial Chemistry. Almost 250 students are admitted. After one year, in the 2nd grade, they will be distributed into three different courses. Three classes divided mechanically. In the 4th grade they chose to enter into one the laboratories of the department. Four graduate students choose to enter in my laboratory every year. Kyoto University is a very big university. We have almost 47 chemistry professors for 250 students. 150 graduate students. Two Nobel Prizes came out from this department. It is a prestigious department.

HA : Could we come back to your PhD subject ? How did you choose it ? Was it Professor Soga who proposed it ?

KH : Yes it was about Glass Science. Thermal properties of glass.

HA : From your list of publications I can see that you have worked on many, many fieldswhile working in Professor Soga’s laboratory.

KH : Yes I have been mainly interested in computer simulation of making glass structure and predicting optical properties of glass. I started computer simulation early in the 1980s. It was too early. The computer capacity was very small in the 1980s. Now we have a big project on computer simulation program and we get $5 million over five years from the government for it. Owing to the progress of computers, we can make glass structure containing 10,000 atoms.

HA : Then why did you move to non-linear optics instead of mechanical properties or low temperature behavior ?

KH : It is a good point. One major advantage of glass is transparency. Its major disadvantage is brittleness. Optical fibers are a very important because electrical wires are very limited in speed.

HA : So by the end of the 1980s you guessed that the future of glass for a large application would be optical glasses.

KH : Now we are very lucky. We are also interested in the mechanical properties of glass at the nanolevel. We are dealing with elimination of the nanobubbles. It is very important for industrial companies.

HA : So you got in to the glass making process ?

KH : Yes.

BBV : Was it industrial demand that prompted you to work on optical properties in the 1980s ? Or was it your own initiative, your choice ?

KH : In this period the optical properties were not important for glass industry. Now many glass companies are interested. So now we have a lot of industrial contacts. Before next year we intend to produce 3 commercial optical glasses called photonic glasses. For this, we need connections with venture business.

BBV : Do you mean that you conducted all these researches on optical properties without industrial support ?

KH : No, only in the beginning. Now we get a lot of industrial support. But now I get a lot of budgets from three kinds of government projects, not only from industry. We have 3 projects. One is computer simulation. One is on photoactive glass in cooperation with foreign countries. So we have a lot of post-docs in my laboratory. The third one is the nanoglass project.

HA : Could you tell us about this nanoglass project ?

KH : The government launched a nanotech program that covers a variety of projects : nanometals , nanopolymers, carbon nanotubes, nanocoatings, nanoparticles, nanosimulation and the nanoglass project. For the latter, we get $30 million for 5 years approximately.

HA : How do you spend this amount of money.

KH : Most people involved in the glass project are coming from industry, from Asahi Glass, Hoya, Nippon Electric Glass, Central Glass, Okamoto Glass, Nippon Yamamura Glass, Hitachi, ... 11 companies sent us 15 researchers whose salaries are paid by the project.

HA : How many people are working in your nanoglass project ?

KH : 100 people including the supporters. They join in Tsukuba consortium, from Osaka Institute and several university professors also support us.We have some large equipment.

HA : When did this project start ?

KH : We had a preliminary year and the project itself started in 2001.We have got a number of results. For instance CVD deposition. We also succeed in making very low optical loss glasses. We have reached 0.005dB/cm. This glass will be very useful for making waveguides. In Tsukuba we use two kinds of femtosecond lasers working at 1 kHz and 200 kHz. By using these femtosecond lasers, we not only write in waveguides but also we make crystals from glass, for example silicon crystals from amorphous silica.

HA : Last time you mentioned that you also have a laboratory in China working on crystal growth.

KH : That is right. And we have also made a lot of semiconductors, single crystals in glasses by using this material and we made photonic crystals, which can be used as optical filters.

HA : Where does the money for this nanoglass project come from ?

KH : From NEDO. It is part of METI (Ministry of Economy, Trade and Industry). No connection with AIST although METI also supports AIST. We also made a very tough glass whose strength is very high, 2 times that of standard glass. With the femtosecond laser we made very small dots, nanosize dots, that stop the cracks. We have already succeed.

HA : Was it enough to make these tiny holes on the surface ?

KH : They are under the surface. Also by using the interference technique we have made a lot of dots.

HA : I understand, it is beautiful glass but too costly for bottle makers.

KH : Of course it is not for bottle makers ! Also we have found a cheap process to make AWG (array wave-guide grating) by using the femtosecond laser. AWG are very useful for optical telecommunications. Until now, they were very expensive to make. We also managed to make a nanoglass thin film for CD. The storage medium can be a cobalt oxide-based glass, for example. When we apply a nanoglass coating on this recording material the blue beam is shrinked to ¼. This is a lens effect. We have now this optical disk standardized by Hitachi. So you know that Shuji Nakamura ; a Japanese researcher, has discovered the blue laser diode. In my case by using this blue laser diode, the recording capacity is approximately increased by a factor 4, because the beam is much smaller. And in the field of optoelectronics, we have made 3 dimensional devices including both electrical and optical circuits. We use gold containing glasses that crystallize under laser beam. Three dimensional wires can be obtained, together with optical waveguides in the same device.

HA : So this program seems to be essentially telecommunication oriented.

KH : Yes NEDO asked us to make such devices. Otherwise they would cut the financial support.

BBV : You mean that the budget is according to your practical results.

KH : Yes.

BBV : What kind of connections do you have with venture business ?

KH : For optical properties we have to make such connections. Otherwise we could not do it on university money or government money. Venture business have a lot of demands in optical properties of glasses. For instance some fibermakers make lenses inside optical fibers. With my technique of femtosecond laser we can make lense in fiber. There are many such innovations of interest for business, although optical properties are not directly related to optical devices.

BBV : Do you mean that you only do research and no development ?

KH : Optical properties are synchronized with optical devices. There is no linear sequence from optical properties to technical devices, from basic research to applied science then development. We have to work in synergy.

HA : So do you consider yourself as a materials scientist because you are dealing with devices ?

KH : Yes we have to make connections with venture business and industry. For doing this kind of research we have to build a wide network. So many venture businesses are connected with me and they are eager to be.

HA : Where does the money come from ? From big industrial companies ?

KH : So far my devices did not cost much. If one day we have to develop a costly device, the Japanese governement is able to support us immediately, at least for two or 3 years. The Japanese governement is encouraging this kind of cooperation.

HA : Do you also collaborate with foreign companies ?

KH : With Schott in Germany. They have sent a researcher here. And Corning is also willing to collaborate. In the USA glass professors are not so many in optical devices. Here we have more than 50 professors of Glass Science

BBV : Do you send students to the USA ?

KH : Not right now.

HA : Where do you locate the leading centers in your field ?

KH : I guess Osaka is the center. Glass science originated in Osaka National Center.

HA : You told me last year that you run many laboratories. How many ?

KH : I have 6 laboratories including one in China, one in Osaka, one Tsukuba ... 300 people altogether. There are autonomous and eager to make things because optical devices is a very promising field. So I don’t have to be continuously behind them. There are so many things to do such as inkjet using semiconducting cadmium selenide nanoparticles. The color changes depending on particle size.

HA : This is not glass. Is it ?

KH : Yes it is, because nanoparticle CdSe particles are made in micelles and encapsuled by glass using sol-gel chemistry. The fluorescent yield increases nearly 10times using these nanoparticles. Silica sol-gel coating is necessary ; otherwise the semiconductor particles aggregate to each other. Encapsulated particles are then deposited by inkjet to make displays. We do this development by collaborating with venture business.

BBV : So you seem to work as a partner of venture business, as a manager of projects rather than as a traditional scientist supplying science for applications downstream.

KH : Yes my aim is really to make optical devices. This is what we have to do. We teach Glass Science. But in laboratory research we have to make devices. Traditional professors are not interested in devices ; I am. But you see, in Japan I don’t have to move to an industrial company to make such devices.

BBV : Is it part of your obligations as a university professor to make devices ?

KH : No, teaching is the only obligation. We just have to teach and take care of the students.

BBV : Does the university system recognize your devices ?

KH : Yes now the government recognizes patents.

HA : So you feel that you are in a better position at the university because you have the freedom of choosing your topics of research and you have the money that you need for them.

KH : Yes I am very lucky.

BBV : How do you select your research projects ?

KH : The keywords are glass and optics. We have a lot of choices. One criterium is to use the femtosecond laser.

HA : You mean that you can use it to change glass composition ?

KH : If we use samarium doped glasses we can change the samarium3+ to samarium2+ with the femtosecond laser. So glass composition is very important for me. Not just to make new glasses and measure their optical properties. If we make a new glass it is to make a new device by using a new technique. We also made electrical lithography by plasma etching for nanodevices, in Osaka.

HA : On our webpage you also mention that you are working on hybrid materials.

KH : Yes usually at the macroscale, it is difficult to combine organic and inorganic components. Nanohybrids work better by using chemical reactions with micelles. Professor Tetsuo Yazawa at Himeji Institute of Technology University made a lot of nanohybrids that can be used for gas filters, for membranes, solid sensors and solid electrolytes. Conductivity is very high in the nanohybrids. Both electronic and ionic conductivities. And hybrids are also useful for glass capsules for drug delivery. So we started that kind of research on hybrids within the nanoglass project.

BBV : Do you try to compete with other materials in your nanoglass project ?

KH : No, glass offers unique advantages. We can overcome polymers. Glass is the only transparent material even at the nanoscale. I forgot ! Athermal glass is very important. We achieved athermal glass-ceramics we have to apply pressure to control the size of the nanoparticles and the growth. So nanoglass is unique and very useful.

HA : I can see that your project works very well. But do you remember any failure in your research career ? It is also instructive for our project on the history of Materials Science.

KH : For the Photoncraft project we are at the middle point so we have to submit. The nanoglass project started one year ago. We have to make an effort, otherwise budget might be cut.

HA : This morning Professor Soga told us that he considers himself as an educator rather than as a glass scientist. Is teaching and training also important for you ?

KH : You cannot separate teaching and research. Education and laboratory work together. In the field of glass, just making optical devices is a good education, a good training. Now we are training a number of students through the nanoglass project.

BBV : Do you mean that the nanoglass project is in itself a kind of training ?

KH : Yes, for graduate students. When I present the results of our nanoglass project to company presidents, they are essentially grateful for our work as educators because we train the researchers from industrial companies. Helping each other is very important.

HA : Does it mean that you are no longer interested in basic research and basic education ?

KH : No. Presently I am making devices but maybe in a few years I write a new textbook of glass science because they are so many new glasses that all conventional glasses are obsolete. This textbook should be written in English.

BBV : You want to write a textbook of Glass Science, not of Materials Science in general ? Are there any Japanese textbooks of Materials Science ?

KH : Yes and we had written one.

BBV : One final question : Do you see differences in the research styles of various countries ?

KH : In Europe originality is important. Here it is rather collaboration and harmony. We are more modest, more humble. Collaborations, mutual help and mutual learning, Interdiscipinary philosophy is my project aim.

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