Photocatalysis enables redox reactions to proceed non-thermally under ambient conditions, offering a low-energy alternative to conventional thermocatalytic processes. Traditionally, it has been assumed that oxidation occurs exclusively at the semiconductor surface via photogenerated holes, while reduction takes place on metal cocatalysts that capture photogenerated electrons. However, the absence of microscopic insights into the detailed reaction mechanism has hindered rational design of catalysts. To address this, we employed kinetic analysis and operando infrared spectroscopy to directly monitor reactive species under reaction conditions. Our investigations reveal that metal cocatalysts also play a crucial role in oxidation by interacting with photogenerated holes, contrary to traditional understanding. Moreover, the reactive electrons are not located within the metal cocatalysts but are shallowly trapped in in-gap states of the semiconductor surface at their periphery. These findings redefine the concept of catalytic active sites and provide a basis for designing more efficient photocatalytic systems.

Electron beam powder bed fusion (EB-PBF), one of additive manufacturing, utilizes an electron beam as a heat source and has advantages such as a scanning strategy with high-speed operation, high thermal conversion efficiency, and residual stress relief by preheating process. On the other hand, it has inferior surface roughness, a powder scattering phenomenon known as smoke, and the need to remove pre-sintered powder. In addition to these general features of EB-PBF, other features of EB-PBF have been developed in recent years : high-quality electron beam, and defect detection through backscattered electron (BSE) image monitoring. EB-PBF is suitable for Ti-6Al-4V alloys, pure copper, Ni718 alloys and pure tungsten, and meets AMS standard certification, crack-free and microstructure control.

Hydrogen readily permeates various materials and modulates their physical properties. Identification of the hydrogen lattice location in crystals is key to understanding and controlling the hydrogen-induced phenomena. Combining nuclear reaction analysis (NRA) with the ion channeling technique, we experimentally determined the locations of H and D in epitaxial nanofilms of titanium hydrides. We found that 11 at.% of H are located at the octahedral site with the remaining H atoms in the tetrahedral site. Density functional theory calculations revealed that the partial octahedral site occupation is attributed to the Jahn-Teller effect induced by hydrogen. In contrast, D was found to solely occupy the tetrahedral site owing to the mass effect on the zero-point vibrational energy. This study demonstrates the potential to fabricate hydrides with arbitrary site occupancy by tuning the isotope ratio, which potentially allows for control over their electronic properties and leads to the discovery of novel phenomena.

The metal–insulator transition (MIT) in VO₂ is strongly governed by nanoscale morphology and structural defects. To elucidate the microscopic origin of this transition, we investigated the relationship between surface structure and MIT dynamics in VO₂ thin films epitaxially grown on TiO₂(110) via pulsed laser deposition. Operando X-ray diffraction confirmed a structural transformation from the monoclinic (insulating) to rutile (metallic) phase. Infrared scattering-type scanning near-field optical microscopy (s-SNOM) enabled direct visualization of individual anisotropic nanodomains with nanoscale resolution. The contrast in near-field amplitude allowed us to spatially resolve metallic and insulating phases across the surface. We observed that metallic domains nucleate and expand heterogeneously, influenced by local grain geometry and anisotropic strain along the [001] direction. These findings provide insight into the interplay between structural features and phase transition pathways in strongly correlated oxide systems.

Data science has emerged as the fourth scientific method, following experiment, theory, and computation. Since the launch of the Material Genome Initiative in 2011, data-driven approaches such as materials informatics and process informatics have been actively applied in materials. To integrate data science into traditional research, it is essential to understand research activities as a data cycle consisting of three phases : data generation, accumulation, and utilization. This cyclic process enhances the efficiency and scope of scientific research. To illustrate the impact of data science in materials research, this paper introduces Bayesian optimization for autonomous experimental system, machine learning potentials, personal databases using JSON format, and high-throughput automatic spectral analysis. These approaches contribute to the advancement of materials science through data-driven methodologies, accelerating the data cycle.

We review our recent study on the electronic states of Te(0001) using high-spatial-resolution angle-resolved photoemission spectroscopy (ARPES) with micro-focused synchrotron light. The results demonstrate the formation of in-gap states confined to the edges, and support topologically nontrivial character of Te helix chain.

Development of operando soft-X-ray surface spectroscopy techniques using near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and ambient-pressure soft-X-ray absorption spectroscopy (AP-sXAS) and their application to operando observations for surface catalytic reactions are reviewed. First, we will explain soft-X-ray surface spectroscopy end-stations that we developed for operando observations at the Photon Factory. As for the application, we introduce studies on CO oxidation on Pt-group metals and their alloys and photoinduced carrier transfer to cocatalysts on a SrTiO₃-based photocatalyst. We will also discuss future advancements of the operando soft-X-ray surface spectroscopy techniques.

Superconducting qubits are one of the promising hardware candidates for quantum computing, and the operation of quantum processors equipped with more than 1000 qubits have been reported. However, to achieve a meaningful quantum computation that has an advantage over classical computation, further improvement in gate fidelity and more precise control of circuit parameters are required, and many challenges remain in realizing such hardware. In this article, we summarize the current status and challenges of superconducting qubits with a focus on the circuit fabrication process and present our research and development of superconducting qubits using nitride superconductors.

In recent years, the automation of materials research has become a crucial challenge. Powder X-ray diffraction (PXRD) is essential for characterizing material properties, but current methods face issues with reproducibility and efficiency. To address this, we have developed an autonomous experimental system using robotics and machine learning. This article introduces the configuration and workflow of the developed system. Additionally, we discuss the performance evaluation of this system and compare it with conventional manual experiments.

This paper describes the international standardization activities of ISO/TC201/SC9/WG7, including the standardized method and a new method currently undergoing international round-robin testing for local elastic modulus measurement using atomic force microscopy, future prospects including extension to viscoelastic measurement. This paper will also include examples of how the local elastic modulus measurement method can be utilized in the materials industry.

Sealing inspections have been carried out to ensure the reliability of the sealing products in various industrial fields. The methods include waterproof tests based on ingress protection (IP) code, environmental testing at high temperature and humidity condition, babble testing, leak testing with pressure difference method (air leak test), helium leak testing, and so on. This overview article summarizes the latest trends of these testing methods. Recent requirements on the accountability for sealing inspections in the medical field and the activities using reference test peaces in the field of measuring instruments are also introduced.

A solid electrolyte-based physical reservoir utilizes ions’ diffusion and their redox reactions to achieve nonlinear transformation of input and its short-term memorization. One of the major advantage in using a solid electrolyte is easy fabrication of a recurrent neural network with a large number of ‘nodes’, which enables various functions unique to the material-based physical reservoir such as in-sensor computing.

There are a wide variety of measurement techniques that produce spectra as output datasets. Existing data analysis software and some open-source macros are useful but not sufficient for non-experts to perform peak-fitting analysis and interpretation. Therefore, we have investigated analysis method using unsupervised machine learning for high-throughput and automated peak deconvolution analysis of spectra without prior knowledge of experimental techniques and material databases. In this paper, we will introduce the open-source package called “EMPeaks”, including development chronology, specific usage, current issues, and analysis examples.

The rapid advancement of software-based deep learning has led to a surge in AI applications, yet hardware limitations in silicon CMOS technology hinder performance. Consequently, interest is growing in hardware technologies and new materials for artificial neural networks (ANNs) and neuromorphic systems. Exploiting nanomaterials nonlinearity caused by spontaneous physical phenomena holds promise of reducing power consumption in AI hardware. Reservoir computing devices, derived from recurrent neural networks, play a crucial role, with material reservoir devices showcasing “material intelligence.” Tailored nanomaterials for reservoir devices hold potential for revolutionizing AI, especially in robotics. As research progresses, focusing on device functionalization and applications, recent findings underline the significance of integrating nanomaterials into AI hardware for enhanced computational capabilities and energy efficiency.

Nb has the highest superconducting transition temperature among elemental materials, which makes it a realistic choice for superconducting junctions. However, self-organized oxide structures on its surface impede the preparation of well-defined interface. Once the oxide structure is clarified, this oxidized surface may be used as an interface. Atomic force microscopy can distinguish different elements among ionic crystals depending on the charge state of the scanning probes. We applied this method to the oxide surfaces of Nb(110) for structural analysis and observed Nb and O atoms independently as well as simultaneously. A structural model was constructed based on the density functional theory. Additionally, the density of states and the Bader charge were analyzed.

Lithium–oxygen (Li–O₂) batteries have attracted considerable attention as prospective next-generation energy storage devices because of their highest theoretical energy density among all rechargeable batteries. Although fundamental researches focusing on the properties of the solid-state discharge products have been conducted to elucidate the factors that contribute to large charge overvoltages, many questions remain unanswered. In particular, due to the main discharge product being a peroxide, which cannot remain stable in the atmosphere, its formation process, properties, and the relationship between the surface structure and its reactivity are not fully understood. The present article aims to introduce the latest understanding of the reductive growth and oxidative decomposition processes of discharge products, particularly from a surface science perspective.

The behavior of materials at the sliding contact is extremely challenging to determine since the contact area is normally hidden from view. We therefore have developed a custom-designed apparatus that enables us to observe the actual contact area while simultaneously measuring the friction/normal forces. From this, we found the von Mises stress applied at the contact area at yield approach the ideal strength of Ag and 20 times higher than that for bulk Ag. The results strongly suggest that the actual contact area at the sliding point forms an amorphous layer and slides while deforming the layer. That indicates we may overestimate the actual contact area and underestimate the stress applied at the contact area if those results were not considered.

The local imaging technique, which is able to directly visualize the catalytic activity originating from the structural heterogeneity of the catalyst, is significantly required to provide the guidelines for the development of the new catalyst with an ability of efficient activity. Scanning electrochemical cell microscopy (SECCM) is one of the promising candidates because of the ability to obtain the distribution of redox activity on the sub-microscale by forming the meniscus on the sample surface using a nanopipette. We have so far developed single-barrel SECCM to further improve its spatial resolution. In addition, we have applied this technique to various catalysts, for instance, MoS₂ and SnS₂ nanosheets and TiO₂ nanotube. Here, we present the principle and setup of single-barrel SECCM and its applications to the chemistry of catalysis.

This report describes the usage, specification, troubles and the countermeasures of dry pumps in Japan Proton Accelerator Research Complex (J-PARC). In J-PARC, while dry scroll pumps (DSP) are widely used, many of them are being replaced with roots pumps due to frequent maintenance and troubles of DSP. Some of the facilities use roots pumps with special specifications, such as radiation resistant specifications, separate power supply, and with diaphragm type, etc. Although some problems have occurred with both DSPs and roots pumps, they have been addressed by revising maintenance methods and improving parts, contributing to stable operation for users.

X-ray Photoelectron Spectroscopy (XPS) is widely used as one of the primary techniques for investigating the surface chemical composition of materials. In recent years, there has been a significant increase in the demand to observe the electronic states associated with chemical reactions under operating conditions close to real environments, such as in fuel cells and catalytic materials. To address this need, Near Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS) instruments have been developed and continuously improved. This article introduces atmospheric pressure photoelectron spectroscopy at pressures of several bars and provides data examples. Additionally, we present software technology designed to visualize spatiotemporal-resolved data expected to be obtained in the future using this measurement technique.