Site: The University of Tokyo
Department of Chemical Engineering
Faculty of Engineering
Kogakukan #5, Room 709
Bunkyo-ku, Tokyo 113, Japan

Date Visited: 22 July 1997

WTEC: D.T. Shaw (report author)

Hosts:

BACKGROUND

The University of Tokyo is the oldest and the most prestigious university in Japan. Prof. Komiyama belongs to the Department of Chemical Systems Engineering, which is one of three departments (the other two are the Department of Applied Chemistry and the Department of Chemistry and Biotechnology) in the Department of Chemical Engineering. His work on nanoparticles has focused on the synthesis and optical properties of nanocomposites of metal/organic, organic/metal, metal/semiconductor, and semiconductor/ semiconductor particles. More recently, coated self-assembled nanoparticles have also been studied.

Overall, Prof. Komiyama's work on nanoparticles and nanoparticle structures has focused on fundamental studies of the effects of quantum confinement of heterostructured nanoparticles and nanoparticle structures. Prof. Komiyama's laboratory is extremely well equipped and has formed strong connections to other research laboratories both within and outside Japan. At the present time, all his research projects appear to be experimental. In fact, the last theoretical work was conducted in cooperation with Prof. Joseph W. Haus (Physics Department, Rensselaer Polytechnic Institute, RPI) who visited him for one year in 1992.

RESEARCH AND DEVELOPMENT HIGHLIGHTS

Dr. H.S. Zhou, who is now a researcher at the Electrotechnical Laboratory at Tsukuba City, showed me his work with Prof. Komiyama on the study of conformational change of protein cytochrome b-562 absorbed on colloidal gold particles. Cytochrome b-562 is a small cylindrical haem protein (diameter ~2.5 nm and height ~5 nm) found in the periplasm of E-coli. Depending on the degree of coverage, the protein on the gold particles (diameter ~ 31 nm) can be in side-on or tail-on conformation. Maximum optical shift occurs when protein particles are in side-on conformation with an effective composite particle size of 36 nm. Other work in this area includes the synthesis of semiconductor/semiconductor (such as Cds/PbS) and metal-coated (such as AuS/Au, Ag/polydiacetylene) particles. Some of this work was partially inspired by the theoretical work carried out while Prof. Haus was visiting Tokyo University on leave from RPI in 1992. In recent years, special emphasis has been placed on experimental projects because of the great influx of equipment funds from the government. At present, nanoparticles are fabricated by colloidal chemical vapor deposition and physical vapor deposition techniques (e.g., laser ablation, sputtering, and electron cyclotron resonance).

Dr. Fumihiro Wakai was invited by Prof. Komiyama to make a presentation on his work on superplasticity. Dr. Wakai was associated with the National Industrial Research Institute of Nagoya. He is now a professor at the Center of Materials Design at the Tokyo Institute of Technology in Yokohama. His work (Nature 1990. 344:421) on Si3N4/SiC composites has led to the discovery of superplasticity in nanocrystalline covalent ceramic materials. Currently, he is also the director of a large cooperative project between Japan and Germany (Prof. Fritz Aldinger, Max-Planck-Institut für Metallforschung), supported by the Japan Science and Technology Corporation, that commenced its operation in October 1966. The objectives of the cooperative project are to explore the nanostructures of the superplastic grain boundaries and to develop new synthesis techniques for maximum superplastic deformation at elevated temperatures. In addition, Prof. Komiyama mentioned the possibility of investigating the miniaturization of superplastic testing and characterization with a very small amount of materials.

CONCLUDING REMARKS

Although I spent all of my visit with Prof. Komiyama's group, there are several other groups at the University of Tokyo that are conducting significant research in nanotechnology. These include the Physics Department (theoretical and experimental work on quantum-confinement and functional materials) and the Department of Applied Chemistry (TiO2 particles).

Although my two-hour visit concentrated on composite nanoparticles/nanostructures as described above, I know from my previous visit in October 1996 that Prof. Komiyama is also active in areas related to amorphous silicone and other metal and semiconductor nanostructured materials. He is one of the research leaders in the one-step CVD synthesis of AlN, TiN, SiN, SiC, TiC, and ZrO (single or two components) nanostructured materials.


Published: September 1999; WTEC Hyper-Librarian