The flux method is one of the niche sciences for crystal growth. It is a type of liquid-phase growth method and is the most versatile method for growing single crystals. For flux growth, the components of the desired substance are dissolved in the flux, and crystal growth (and crystal layer formation) takes place at a relatively low temperature. One of the important advantages is that crystals can grow free from mechanical or thermal constraints in the solution and the grown crystals have well-developed facets. By combining computational science and the flux method, we are particularly focusing on the development of visible-light-driven photocatalysts, all-solid-state lithium ion batteries and inorganic ion exchangers from the viewpoints of material design, crystal growth and device fabrication.

The atomic layer etching (ALE) technique was developed to obtain fine control of etching reactions with atomic-layer level precision, by separating the adsorption reaction and the activation reaction into discrete steps. In the ALE process, it is critical to achieve a self-limiting reaction where the reaction stops after the etching of a complete atomic layer. By using the self-limiting reactions of ALE, it is possible to realize fabrication processes beyond the sub 5/7 nm technology node. We explain the fundamental principle of ALE and the effect expected from it. In addition, the various ALE approaches developed for different materials and application processes are outlined. Attention is currently focused on the ALE technique for precise control of the etching reaction on a wafer.

Near-infrared photoluminescence of single-walled carbon nanotubes is expected to be used for light emitting materials in optical communication light sources and bioimaging. For their practical applications, it is an important issue to improve their low PL quantum yields. Recently, local band-structure modulation has been achieved by appropriate chemical derivatization to allow bright new-red shifted PL peaks to emerge. Interestingly, it has been revealed that the PL wavelength and intensity are tunable depending on the chemical reaction, the structure of the reagents used, and the degree of functionalization of the carbon nanotubes. The chemical functionalization of carbon nanotubes is highly desirable owing to its applicability in various NIR PL applications.

Negative thermal expansion materials are expected to be utilized for the control of the thermal expansion of structural materials in the fields of semiconductor manufacturing, optical devices and precise machining where precise positioning is required. In this review, giant negative thermal expansions in BiNi_1-xFe_xO₃ induced by intermetallic charge transfer and in Pb_1-xBi_xVO₃ induced by a ferroelctric-paraelectric transition, and a zero-thermal expansion composite with epoxy resin will be discussed.

Over the last decade, there has been great progress in research to control thermal-phonon transport by nanostructures, and the field of "phonon engineering" is attracting a lot of attention. In this review, I describe recent advances in inhibiting the thermal transport of crystal materials, which are potentially useful for various applications such as thermolectrics. Some on-going developments in the field are discussed: investigations of the ultimate boundary scattering of phonon particles, new strategies to modulate the propagation of phonon waves, and the optimal design of nanostructures using materials informatics.

The automotive industry has transformed its products from internal combustion mobility to smart mobility during this once in a century period of change. Lithium ion batteries play an important role in smart mobility, but new problems are emerging in terms of the drain on resources, environmental burdens, and safety performance as batteries become larger and the market is growing dramatically.

The present authors are studying the development of functional glass-ceramics in order to develop battery materials. In this paper, we describe the crystallization mechanism of phosphate glass containing alkali and acid transition metal oxides and their functionality as an active material in a sodium ion battery, and we also describe the demonstration of all-solid state batteries that operate at room temperature without any pressurization.

Magnetic domain structures are known to reflect the fundamental magnetic properties of materials. Observation of the magnetic domain structure is important for understanding the magnetic characteristics of systems, including practical magnetic materials. Most existing techniques are, however, limited to the observation of surfaces where the magnetic domain structures are two-dimensional. In this study, we developed an X-ray tomographic technique to see through the internal magnetic domain structure in a micrometer-sized ferromagnetic sample by reconstructing the three-dimensional distribution of magnetization.

An MRI is a 3D bioimaging method used for both medical and biological research and it uses the same principle as nuclear magnetic resonance (NMR). In addition to hardware development, methodological improvements such as pulse sequence development, analytical methods including data processing, and the development of contrast agents have grown continuously for over 25 years and have allowed for various applications. In this paper, we outline the basic knowledge of a functional MRI and contrast agents.