High-entropy alloys have very promising mechanical properties including high strength and excellent ductility. They also have special functional properties such as high resistance to radiation. For this reason, many related research projects have been rushed into high-entropy alloys in recent years. In rolling deformation studies of high-entropy alloys important for the practical application, it is essential to clarify how interstitial carbon addition affects the deformation behavior of these microstructures with large initial crystal lattice distortions induced by the remarkable atom size differences among the component elements in these alloys.

Here, the research team including Prof. Wei FANG at Hebei University of Technology, Dr. Pingguang XU at Japan Atomic Energy Agency and Prof. Fuxing YIN at Guangdong Academy of Sciences, et al. investigated the influence of interstitial carbon addition on the texture evolution of high-entropy alloys during cold rolling using RESA instrument at JRR-3 neutron facility together with electron channeling contrast imaging and electron backscatter diffraction. Neutron diffraction measurement showed that though their texture components are similar at the early stage of cold rolling, the Brass- and Goss-oriented grains in the carbon-added alloy after 50 % cold rolling are with higher orientation distribution density than those in the carbon-free alloy. The research team successfully clarified that the carbon addition finally promotes the formation of these two special grains during cold rolling (as summarized in Fig.1). The further optimization of the related microstructure-texture control techniques of high-entropy alloys will accelerate the development of new structure-controlled functional materials with superior resistance to radiations, towards the potential application to the space and nuclear power industries.

On the development of organic-inorganic hybrid materials like car tire, we have to introduce coupling agent between the organic and inorganic materials to make a strong binding. However, it has been difficult to observe the coupling layer between the organics and inorganics, and confirm that the coupling layer is chemically and/or physically bound strongly to the organics and inorganics.

To overcome the difficulty, we used spin-contrast-variation neutron reflectivity, which determines surface and interface structure of multilayer films from proton-polarization-dependent polarized neutron reflectivity curves. We successfully measured interpenetration between silane coupling agent and polybutadiene at their interface, and the interpenetration plays an important role on the binding between the polybutadiene and silica that is chemically bound to the silane coupling agent.

Urushi is an ancient super paint that is so stable that it can be found in the ruins of the Jomon period (the time between c. 14,000 and 300 BC). The addition of iron powder to the lacquer gives it a beautiful, deep, and elegant black color. Scientifically, it was known that the addition of iron ions causes the lacquer paint film to dry faster. Furthermore, it has recently been discovered that black lacquer has a catalytic function that promotes the decomposition of harmful substances. However, it is difficult to analyze stable black lacquer, which has a black color that absorbs visible light, and the mechanism and internal structure of black lacquer remain a mystery even today. Unraveling the mysteries of black lacquer will help in further analysis of historical heritage and in the development of new functional materials using lacquer.

In this study, Dr. Takuya Nankawa and his colleagues succeeded for the first time in observing iron ions and special nanostructures inside black lacquer using synchrotron radiation and neutron beams, which have excellent ability to penetrate materials and can detect minute amounts of internal components. We also revealed that iron ions act on the structuring of urushiol, an organic component of lacquer, and that the arrangement of urushiol creates a beautiful black color.

We discovered that a tough porous cellulose hydrogel material can be created by simply mixing cellulose nanofibers and a very low concentration of sodium hydroxide, freezing them, adding citric acid, and melting them. Freezing a solution containing cellulose and sodium hydroxide caused a crystalline phase transition in the cellulose, contributing to its high-strength gelation. The developed gel material has a wide range of functionality that can be applied to metal and carbon dioxide adsorption materials in the future.

Spin-contrast-variation (SCV) small-angle neutron scattering (SANS) is a technique to determine the nanostructure of composite materials from the scattering of polarized neutrons that changes with proton polarization of samples. The SCV-SANS enabled us to determine structure of nanoice crystals that were generated in rapidly frozen sugar solutions by separating the overlapped signals from the nanoice crystals and frozen amorphous solutions. In the frozen glucose solution, we found that the nanoice crystals formed a planar structure with a radius larger than several tens of nanometers and a thickness of 2.5 ± 0.5 nm, which was close to the critical nucleation size of ice crystals in supercooled water. This result suggests that the glucose molecules were preferentially bound to a specific face of nanoice crystals and then blocked the crystal growth perpendicular to that face.

It is widely known that lanthanum hexaboride (LaB₆) is an attracting material of the electron source. The coating of LaB₆ with hexagonal boron nitride (hBN) results in lowering its work function from 2.2 eV to 1.9 eV and increases electron emission. The formation of an 'outward dipole moment' at the interface between hBN and LaB₆ was found to be the cause of the lower work function owing to the hBN coating. The results of this research are expected to lead to higher performance electron microscopes, electron beam lithography equipment and synchrotron radiation facilities.

We have elucidated the growth mechanism of silicon oxide films by real-time photoelectron spectroscopy using the high-brilliance synchrotron radiation at SPring-8.

Silicon (Si) is one of the most fundamental materials that support the modern semiconductor industry. Integrated circuits that control computer operations contain numerous "transistors", which are elements made by oxidizing Si substrates. The size of each transistor has become extremely small, so there is a need to precisely control the oxidation reaction and to fabricate a high-quality oxide film with few defects on the Si substrate. However, the oxidation reaction mechanism in such an atomic-scale film thickness region has not been fully understood.

In this study, we have sequentially observed the Si oxidation reaction progressing in the nano-level world by real-time observation using synchrotron radiation at SPring-8. As a result, the reaction mechanism involving carriers such as electrons and holes, which were previously thought to be unrelated to the oxidation process, was clarified for the first time in the world.

This research is expected to contribute to the improvement of power saving, miniaturization, and reliability of silicon devices.

This research was conducted in collaboration with JAEA, Tohoku University, and Fukui National College of Technology, and was published online in the "Journal of Chemical Physics" on December 20th (Japan Standard Time).

Spin excitation of an ilmenite FeTiO₃ powder sample is measured by time-of-flight inelastic neutron scattering. The dynamic magnetic pair-density function DM(r, E) is obtained from the dynamic magnetic structure factor SM(Q, E) by the Fourier transformation. The real space spin dynamics exhibit magnon mode transitions in the spin–spin correlation with increasing energy from no-phase-shift to π-phase-shift. The mode transition is well reproduced by a simulation using the reciprocal space magnon dispersions. This analysis provides a novel opportunity to study the local spin dynamics of various magnetic systems.

Radium (₈₈Ra) is a well-known radioactive element discovered by Pierre Curie and his wife, Marie Curie, in 1898. It predominantly exists as a hydrated divalent cation, Ra²⁺, in water environments. However, the hydration property of radium ion, i.e., how radium ions are dissolved in water, remains an open question. Here, we have successfully determined the hydration structure of Ra²⁺ using extended X-ray absorption structure (EXAFS) spectroscopy at SPring-8. Ab initio molecular dynamics (AIMD) simulation also shows that water molecules in the first hydration shell of Ra are less structured and more mobile than those of barium (₅₆Ba), which is an analogous element of Ra. These results indicate that the hydration structure of Ra²⁺ can be more labile than that of Ba²⁺. Our study contributes to a systematic comprehension for the behavior of Ra in water environments.

Americium (₉₅Am), discovered by Glenn T. Seaborg's group in the autumn of 1944, is contained in high-level radioactive waste from spent nuclear fuels. Due to its radiotoxicity, geological disposal is most likely way for handling americium with the exception of nuclear transmutation. To reduce the volume of nuclear waste, therefore, we are required to develop precise separation and purification techniques for americium. However, in particular, mutual separation, i.e., separation of neighboring elements on the periodic table, is potentially challenging. This is because chemical properties of neighboring elements are quite similar in same oxidation state. Here, we show resonance-enhanced multiphoton charge transfer in americium complex, which leads to element-specific control of their oxidation states owing to the distinct electronic spectra arising from resonant transitions between f orbitals. We observed oxidation of trivalent americium, Am^III, to pentavalent one, Am^VO₂⁺, in nitric acid. Furthermore, we demonstrated selective photooxidation of Am^III in the presence of praseodymium (₅₉Pr) followed by separation of Am^VO₂⁺ with solvent extraction method. The resonance-enhanced photochemical process could be used in the nuclear waste management, as it would facilitate the mutual separation of actinides, such as americium and curium (₉₆Cm).

A research team of JAEA and other institutions has developed a new conventional technique for measuring the magnetic moment of magnetic materials. The signal from the magnetic element is obtained by the interference of the scattering from the ordered moment with the nuclear spin polarized by the on-site hyperfine field at very low temperatures. The nuclear polarization has been confirmed by measuring the hyperfine spectra of the magnetic atom using the Biomolecular Dynamics Spectrometer (DNA) at J-PARC's Materials and Life Science Experimental Facility (MLF). This method shows promise for future use in areas such as development of new materials used in powerful magnets.

We succeeded in forming nanocubes by hydrothermally synthesizing barium titanate at low temperature. Furthermore, we found that the particle surface of the nanocube was reconstructed with a titanium oxide layer.

A research group led by postdoctoral fellow Yasutaka Tsuda and principal researcher Akitaka Yoshigoe of the Actinide Chemistry Research Group at the Materials Sciences Research Center, Professor Michio Okada of the Institute for Radiation Sciences at Osaka University, and Associate Professor Diño Wislon Agerico Tan of the Graduate School of Engineering has revealed how fast oxygen molecules react to form oxides on the surface of an alloy of copper mixed with palladium and platinum.

Remediating toxic ion contamination is crucial for protecting human health and the environment. This study aimed to provide a powerful strategy for effectively utilizing bone waste from the food production and preparation industries for removal of toxic ions. Here, we show that immersing pig bone in NaHCO₃ aqueous solution produced a carbonated nanohydroxyapatites (C-NHAP). The C-NHAP exhibited high adsorptivity for Sr²⁺, Cd ²⁺, Pb²⁺, and Cu²⁺. The strontium adsorptivity was about 250 and 4,500 times higher than that of normal bone and synthetic HAP, respectively. The C-NHAP is an eco-friendly, high-performance material that dis simple to prepare and should be useful for tackling problems of food waste disposal and environmental pollution.

A research group led by Yukiharu Takeda at Materials Sciences Research Center and Shinobu Ohya at the University of Tokyo has succeeded in extracting only the magnetic information of Mn atoms in (Ga,Mn)As, one of the prototype ferromagnetic semiconductors, by x-ray magnetic circular dichroism (XMCD), which were carried out at BL23SU of SPring-8. By observing in detail how Mn atoms change from a paramagnetic state to a ferromagnetic state on cooling, they have succeeded in elucidating the mechanism of ferromagnetism in (Ga,Mn)As at the atomic level.

A research team led by Dr. Yurina Sekine at the Advanced Science Research Center and the Materials Sciences Research Center has developed a crosslinking method using freeze-concentration and used it to synthesize a new type of carboxymethyl cellulose nanofiber (CMCF) hydrogel with high water content, high compressive strength, and high compressive recoverability. The hydrogels were prepared by adding an aqueous solution of citric acid to a frozen CMCF and then thawing the sol. This gelling process is called freeze crosslinking. The physically crosslinked CMCF hydrogels are non-toxic, metal-free, and simple to prepare, and thus they may be useful as sustainable materials in various fields.

A research group led by Assistant Professor Shuichi Ogawa (Tohoku University's International Center for Synchrotron Radiation Innovation Smart and the Institute of Multidisciplinary Research for Advanced Materials) and Senior Researcher Akitaka Yoshigoe (Materials Sciences Reserach Center of JAEA) has discovered that graphene, a carbon network with a thickness of only one atomic layer, has an anomalous permeable property for oxygen molecule with high-kinetic energies. They found that oxygen molecules can penetrate graphene without breaking the carbon network. This result suggests that the behavior can be controlled by the "speed" of the molecule, and leads to the discovery of even larger molecules passing through graphene.

A research group led by Toru Hirahara at Tokyo Institute of Technology has succeeded in fabrication of a novel magnetic topological heterostructure. They have investigated magnetic properties of the samples on a microscopic level by x-ray magnetic circular dichroism at SPring-8 BL23SU, being collaborated with Yukiharu Takeda at Materials Sciences Research Center. They have demonstrated that the energy gap of the surface Dirac cone closes at a temperature much higher than the temperature at which the magnetic order develops.

Tolerance of spin-Seebeck thermoelectricity against irradiation by swift heavy ions has demonstrated that a "spin thermoelectric (STE) device", which generates electricity from heat, has a very high radiation tolerance. Recently, STE devices relying on electron spins have been developed, and are expected to outperform existing technologies in terms of flexibility in design, low environmental impact, and economic efficiency. However, it has not yet been confirmed whether the device's performance can be maintained in the harsh environment where radioisotopes coexist. To address this, in this study, the service life of the device was estimated by irradiating it with heavy ions, and it was confirmed that the performance of the device would not deteriorate for several hundred years even if spent nuclear fuel was used as a heat source. Moreover, the origin of the deterioration was suggested to be the chemical reaction at the interface of STE device. In the future, it is expected to contribute to the development of new technologies for the safe and effective utilization of waste heat from spent nuclear fuels in the radiation environment.

In some metallic magnetic materials, an unusual short-range order of conduction-electron spins has been observed at low temperatures as a property not seen in ordinary metals, where a partially ordered state emerges in the paramagnetic phase with phase separation. However, its origin is not well understood.
We predicted that one of its origins was the spatial inversion symmetry breaking. To verify this prediction, we have thus synthesized Mn₃RhSi, a new metal magnet without spatial inversion symmetry, for the first time in the world. As a result of complementary neutron and muon spin relaxation experiments, we discovered a "partial short-range order of conduction-electron spins" that is phase-separated from the paramagnetic phase at a record temperature of 720 K (447℃) in Mn₃RhSi. This temperature is much higher than T_N = 190 K. Our discovery is expected to lead to further understanding of the partial order of conduction-electron spins, the origin of which has not been clarified.

The development of steel materials with high strength and high ductility is essential to realize the light weighting of motors and other transportation systems, so that it is important to reliably evaluate and control the textures of steel materials. The crystal diffraction using high penetrating neutrons is well known as the most effective method to obtain the high statistic averaged texture of a bulk steel sample of several cm3. However, the necessary neutron sources are up to now provided only by the limited large science experimental facilities in the world with either a nuclear research reactor or a large proton accelerator.

Dr. Pingguang Xu and his colleagues have successfully developed a novel crystallographic texture measurement technique using neutron diffraction for various manufacturing sites at the first time in the world, through well combing the texture measurement technique on the base of large neutron facilities developed by the Japan Atomic Energy Agency (JAEA) and the RIKEN Accelerator-driven compact Neutron Source (RANS) system developed by the Institute of Physical and Chemical Research (RIKEN), Japan. It is prospected that a new research-and-development (R&D) cycle will come into being soon through integrating the routine R&D activities at the laboratory level with accelerator-driven compact neutron sources and the advanced R&D activities using large neutron facilities, which will lead to rapid development of high-value-added materials and products, and promote spark innovation.

We measured X-ray absorption spectra of amorphous alumina with vacancy-type oxygen defects (AlOx) which exhibits the resistance random access memory (ReRAM) effect. We were able to detect changes in the electronic structure owing to the ReRAM effect. A major difference in the spectra near the O K-absorption edge was observed between a low resistance state (LRS) and a high resistance state (HRS). The subpeak profile within the band gap appeared in the LRS, while it was suppressed in the HRS. By contrast, the spectra near the Al K-absorption edge in the LRS and HRS appeared almost identical, indicating that no byproducts are generated. These findings imply that the distribution of charged electrons primarily changes near oxygen sites from the HRS to the LRS.

The research group in which Takahisa Shobu chief researcher and Toshiharu Muramatsu group leader participate have developed the world's first computational science simulation code SPLICE (residual Stress control using Phenomenological modeling for Laser welding repair process In Computational Environment) that allows general-purpose engineering workstations to evaluate the melting and solidification process of solid metals during laser coating.