• 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.

• We developed both pH and Cl- imaging plates, which can visualize the pH and Cl- concentration on metal surfaces in acidic environments. The pH range is from 3.0 to 0.5, and Cl- concentration up to 4 M can be measured. Fluorescent dyes are successively used for pH and Cl- imaging in the field of biology, but their sensitivity tends to be insufficient in acidic and/or highly concentrated chloride solutions. A glass plate with a sol-gel sensing layer, which contains a pH indicator or a Cl- sensitive florescent dye was fabricated and validated using the solutions with various pH values and Cl- concentrations. Changes in the pH and Cl- distribution on stainless surface in an acidic environment were measured quantitatively.

The newly developed imaging plates can be used to investigate the mechanism of various chemical reactions, such as corrosion, which occurs in an acidic environment. Micro-flow imaging using our sensing technique will be a promising approach to understand the catalytic chemistry of metal surfaces.
強調

• 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 subject of our group is developing material purification methods, crystal growth methods and detector fabrication technologies for compound semiconductor radiation detectors. Our group intensely studies a compound semiconductor, thallium bromide (TlBr), for fabrication of gamma-ray detectors for the advanced radiation applications. The attractive physical properties of TlBr lie in its high atomic number (Tl: 81, Br: 35), high density (7.56 g/cm3) and wide bandgap (2.68 eV). Due to the high atomic number and high density, TlBr exhibits high photon stopping power. The wide bandgap of TlBr permits the device low-noise operation at and above room temperatures.

Our group focuses on development of compound semiconductor radiation detectors for advanced radiation applications including ultra-high resolution PET systems, ultra-high resolution SPECT systems, photon counting CT systems and Compton cameras. We hope to conduct collaborative research with a willing company for a practical application of this technology in industry.

• Fukuyama laboratory studies novel material processing based on chemical thermodynamics with high-temperature thermophysical property measurements. As examples, we are developing new crystal growth processes to bring a breakthrough in nitride-semiconductor devices, which are promising materials for next-generation optical devices applied in environmental, medical, bio and information technologies fields. Database of thermophysical properties of materials is needed for modeling heat and mass transports in materials processes.

A new thermophysical property measurement system is currently under development, which enables accurate measurements of heat capacity, thermal conductivity, emissivity, density and surface tension of high-temperature melts, utilizing electromagnetic levitation in a dc magnetic field.

The sea pineapple is the only animal that produces cellulose, and its shells, excluding the edible parts, are treated as industrial waste. By removing proteins and other components from the sea squirt shells and fibrillating them, cellulose nanofibers (CNFs) can be extracted. We have focused on the fact that CNFs derived from sea squirt shells have a higher degree of crystallinity and greater mechanical strength compared to those from wood, and we are exploring various applications of this material. Furthermore, since the material transforms into high-quality carbon upon calcination, we successfully developed "nano-blood carbon catalysts" by mixing it with dried blood powder and calcining the mixture. These catalysts are being applied in fuel cells, water electrolysis, and metal-air batteries.

CNFs derived from sea pineapple's shells have a higher degree of crystallinity compared to those from wood and provide longer fibers, resulting in high strength. When calcined, they transform into high-performance carbon.

• We are the only research laboratory that has consistently developed a process for the simple and large-scale purification of CNFs derived from sea pineapple's shells, along with the creation of film materials that leverage their unique properties (mechanical, engineering, surface science, electrical, and thermal characteristics), as well as the development of carbonized materials.

We offer materials derived from sea pineapples' shell CNFs, as well as their carbonized products and catalysts. Please feel free to consult us regarding material supply, carbonization processes, or the utilization of catalysts.

• 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.

• Conventional X-ray imaging methods that rely on X-ray attenuation cannot generate clear contrast in the observation of low-density materials such as polymers consisting of low-Z elements. However, the sensitivity to the materials can be improved drastically by X-ray phase imaging that detects X-ray refraction caused by the materials. X-ray Talbot or Talbot-Lau interferometry consisting of X-ray transmission gratings is now constructed in laboratories for X-ray phase imaging. X-ray phase tomography is also realized, enabling high-sensitive three-dimensional observation.
• X-ray phase imaging can be utilized for X-ray non-destructive testing of industrial products and baggage that cannot be checked conventionally.

We aim at appending a phase-contrast mode to micro-CT apparatuses and developing screening apparatuses in production lines.

• We successfully realized millisecond-order X-ray phase tomography using a fringe-scanning method in grating-based X-ray interferometry. We obtained phase tomograms with a measurement time of 4.43 ms using a white synchrotron X-ray beam. The use of a fringe-scanning method enables us to achieve not only a higher spatial resolution but also a higher signal-to-noise ratio than that attained by the Fourier transform method. In addition, our approach can be applied to realize four-dimensional or high-throughput X-ray tomography for samples that can be rotated at a high speed.