• Atomic diffusion bonding of two flat wafers with thin metal films is a promising process to achieve wafer bonding at room temperature. High surface energies of metal films and a large atomic diffusion coefficient at the grain boundaries and film surfaces enable bonding at room temperature without unusually high loading pressure. This technique, which enables bonding of any mirror-polished wafer, is gaining wider use for fabricating optical and electrical devices. Moreover, bonding of mirror polished metals and polymer sheets can be achieved, which further extends the application of this bonding technique.

Optical, power and electrical devices, MEMS, bonding of polymer sheets, metals, and ceramics for precision mechanical equipments.

• Phase change random access memory (PCRAM) has attracted attention as next-generation non-volatile memories. A conventional PCM is Ge-Sb-Te which shows a fast crystallization speed and an excellent reversibility of phase transition. However, Ge-Sb-Te has a low crystallization temperature of about 150 ºC and a high melting temperature of over 600 ºC , which limits data retention and causes high power consumption, respectively.
• We have developed a new phase change materials with high crystallization temperature and low melting point such as Ge-Cu-Te etc, which have high potential as PCRAM materials with high thermal stability and low power consumption (Fig.1,2).

Our materials are developed for PCRAM, DVD recording materials etc. We hope the collaboration research with companies which are interested in our developed phase change materials.

• Tactile sense and the sense of touch are multiple combinations of fundamental sensations, such as smooth and rough, soft and hard, dry and wet, and hot and cold sensations. These sensations are described with the information on force, distortion, temperature, stickiness and oscillation.
• A tactile sensor corresponding to several types of human skin sensory receptors and an active tactile sensor system that is an integrated sensor structure imitating human haptic motions have been developed. These sensor systems allowed measurement of "Kansei" words that are extremely vague tactile feelings, and roughness, softness and temperature sensations. However, tactile sense or the sense of touch also includes other sensations and combinations of them. Therefore, to develop a sensor, it is important to define how the sensations and physical information relating to the sensations are obtained and what relationships exist between them.
• In this research, the relationships between sensations, including fundamental sensations that have already been obtained and other sensations, and the relevant physical information are being investigated. Additionally, on the basis of the knowledge through the investigation, an advanced sensor system that allows obtaining haptic information is being developed.

The research is beneficial not only to life science but also to manufacturing fields.

• We invented supercritical hydrothermal synthesis method for the synthesis of organic modified nanoparticles (NPs). Under the supercritical state, the organic molecules and metal salt aqueous solutions are miscible and water molecule works as an acid/base catalyst for the reactions. Organic-inorganic conjugate NPs can be synthesized under this condition. This hybrid NPs show high affinity with the organic solvent or the polymer matrix, which leads to fabricate the organic inorganic hybrid nanomaterials with the trade-off function (super hybird nanomaterials). These hybrid materials of polymer and ceramics fabricated with NPs achieve both high thermal conductivity and easy thin film flexible fabrication, namely trade-off function.

For example, by the surface modification of BN particles by supercritical method, affinity of BN and polymers could be improved, so that high BN content of hybrid materials, thus high thermal conductivity materials, could be synthesized. Also by dispersing high refractive index NPs like TiO2 or ZrO2 into polymers transparently, we can tune the refractive index of the polymers. CeO2 nanoparticles are expected to be used for high performance catalysts. To transfer those supercritical fluid nano technologies, a consortium was launched with more than 70 companies.

• Intergranular degradation often results in decreased lifetime, reliability and economical efficiency of polycrystalline materials. In spite of persistent efforts to prevent such degradation, its complete suppression has not yet been achieved. Grain boundary studies have revealed that coincidence-site-lattice (CSL) boundaries have stronger resistance to intergranular degradations than random boundaries. The concept of ‘grain boundary design and control' has been refined as grain boundary engineering (GBE). GBEed materials which are characterized by high frequencies of CSL boundaries are resistant to intergranular degradations. Our group has achieved very high frequencies of CSL boundaries in commercial stainless steels by GBE. GBEed stainless steels showed significantly stronger resistance to intergranular corrosion (see Figs. 1 and 2), weld-decay, knife-line attack, stress corrosion cracking, liquid-metal embrittlement, radiation damage, etc. and much longer creep life (see Fig. 3) than the unGBEed ones.

By using this GBE processing, we expect to conduct effective collaborative research in related fields.

• Multifunctional molecular-assemblies and hybrid organic - inorganic materials are examined from the viewpoint of structural freedom of organic molecules. The spin and electronic states of molecular-assemblies are designed in terms of electrical conductivity, magnetism, and ferroelectricity. Diverse molecular assemblies from single crystal, plastic crystal, liquid crystal, gel, to Langmuir-Blodgett film are our research targets, which were hybridized with inorganic gigantic clusters and metal nanoparticles. We are prepared to provide academic consultations to companies interested in our research.