• Microstructure represents various kinds of heterogeneities in the metallic materials, i.e., grains, component phase, lattice defects and chemical inhomogeneity such as impurity/alloying elements. It can be modified through control of phase transformation/precipitation and deformation/recrystallization by adjusting compositions of materials and/or through processing routes (heat treatment, deformation). Such expertise in micro/nanostructure control is very important in production of current materials from viewpoints of energy saving and recycling in structural materials such as steels and titanium alloys.
• We attempt to apply more advanced control of micro/nanostructures, such as atomic structures of crystalline interfaces, chemistory in an atomic scale (e.g., segregation) and so on. Fundamentals of microstructure formation (thermodynamics, kinetics, crystallography) are examined both theoretically and experimentally to clarify key factors for microstructure control. Another important aspect in our research is the improvement of mechanical property by microstructure manipulation.

Possibilities to establish new functions (e.g., superplasticity, shape memory/superelasticity) as well as superior mechanical properties (e.g., ultrahigh strength with high toughness/ductility) is also explored.

• The emergence of stress corrosion cracking is one of the most important issues from the viewpoint of aging management and maintenance of nuclear power plants. There is a large discrepancy between stress corrosion cracking and other cracks such as fatigue cracks from the viewpoint of nondestructive testing and evaluations, which requires suitable specimens containing stress corrosion cracking for the development of nondestructive testing and evaluation techniques and also for personnel training. However, artificially introducing stress corrosion cracking needs large cost and long time. Furthermore, several studies have pointed out that such articial stress corrosion cracking is not always similar to natural ones. On the basis of the background above, we develop a method to fabricate "imitative" stress corrosion cracking specimens using diffusion bonding.

The method enables one to introduce a region whose response is almost identical to actual stress corrosion cracking from the viewpoint of nondestructive testing. Whereas the dimension of the region is accurately controllable, the method requires much less cost and time comparing the conventional ones using corrosive environment. Patent is already applied for.

• 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.

• Monoatomic layered materials of Graphene, Transition metal sulfide nanosheet, nanocrystalline active materials, nanoparticles and nanoporous materials are investigated for realizing high capacity, high power, high safety and low cost energy storage devices as a post- Lithium ion battery. Advanced chemistry of functional materials and device processes for All solid state battery, Magnesium battery, fuel cells, supercapacitor and wearable batteries are investigated.

Academia – Industry collaboration with manufacturing companies of functional materials, batteries, and also smart grid, renewable energy, electrical power companies are encouraged for developments of advanced energy materials and post-Lithium ion battery.

• The main research subjects in this group are the experimental investigations of the organic molecular conductors. The characteristic properties of the organic materials are multiple flexibilities owing to the assemble structure of nanometer-size molecules. This flexbility comes up recently for developing the organic electronic devices. We explore the fundamental electronic properties of the organic molecular materials which have wide range of the ground states from superconductivity to insulating states resulting from the strongly correlated electrons in the molecular pi-orbital. Such features are closely connected to flexible and multiple degrees of freedom in charge, spin, molecular latticeand molecules themselves. We are actively studying on the interesting and important issues in the condensed matter physics from the viewpoints of the characteristic flexbility of the organic molecular materials. We are prepared to provide academic consultations to companies interested in our research.

• In contrast to other scattering techniques, such as x-ray and electron diffractions, neutron scattering has the following advantages: 1) light atoms, such as H and Li, can be detected; 2) electron spins can be detected; 3) low energy excitations can be investigated. Using the neutron scattering technique, we search for macroscopic quantum phenomena in many-body electron systems, such as macroscopic singlet ground states in the quantum frustrated magnets and spin-fluctuation-mediated unconventional superconductors.

As noted above, neutron scattering can be used for investigating magnetic structure, spin dynamics, light atom positions in crystalline materials and their dynamics. Hence, this technique is very useful when those pieces of information are to be known.

• Our research group investigates creation of functional oxides and their functionalities. We synthesize thin films by pulsed laser deposition and sputtering methods and bulk specimens, and develop their novel synthetic routes. Recently, we are studying electrically conducting rare earth oxides, transparent room temperature ferromagnetic semiconductors, and metal hydrides. We will develop our materials design by extending materials range and performing thin film heteroepitaxy.

Collaborative research in fields of oxide electronics with novel electric conducting oxides and oxide spintronics with ferromagnetic semiconductors and novel ferromagnetic oxides.

• We are developing a new continuous flow type process for supercritical reactions. Under the supercritical state, the organic molecules and metal salt aqueous solutions are miscible and water molecule works as an acid/base catalyst which leads to rapid reactions. In order to apply such new reaction fields to an industrial process, it is necessary to establish the process design basis by understanding phenomena in the reaction fields, on the basis of phase equilibrium, flux and reaction kinetics theory. So while developing a process, we are doing research for the establishment of the process design basis.

Examples are a process for the synthesis of organic modified nanoparticles (MPs), a process for the pretreatment and solubilization of biomass in the supercritical/subcritical water and a process for the refinery of heavy oil in the supercritical water.

• Our research group has succeeded in synthesizing various metal oxide nanoparticles with controlled size and exposure crystal planes by using organic modifiers under supercritical water conditions. The oxygen storage/release capacity of those materials in the low-temperature region is very high, and the reforming reaction of oxidative hydrocarbon proceeds at a significant rate. Besides, by combining the supercritical CO2 drying method, we have succeeded in forming a complex in which oxide nanoparticles are dispersed at a high concentration on the surface of the porous material, realizing both high oxygen storage/release capability and stability.

Low-temperature reforming reaction of biomass wastes, heavy oils, and methane. In the future, it is expected to be a technology that will lead to the construction of a low-carbon society, including CO2-free complete recycling of waste plastics.