The reduction strengthening of various rare earth-added ceria-based electrolytes was investigated. Sm³⁺, Gd³⁺ and Y³⁺ were selected as the dopants, and the dependence of the lattice constant and conductivity on the doping amount was investigated. The lattice constant changed linearly with the amount added. Only the addition of Y³⁺ decreased the lattice constant with the addition amount. This is probably because Y³⁺ has a slightly larger ionic radius than Ce⁴⁺, but is affected by the formation of oxygen vacancies. The ionic conductivity increased with the addition of rare earth elements, and showed the maximum value at 20 mol% addition due to the relationship between the increase in carrier concentration and the association of defects. It was found that the conductivity of the sample with Y³⁺ addition was lower than that of the others when the addition amount was the same. A 10-20% improvement in strength was observed when contact reduction was carried out at the composition showing the maximum conductivity. Formation of a surface compression layer due to contact reduction was confirmed by a hardness test with different indentation depths. In addition, XPS confirmed that there is a concentration gradient of Ce³⁺ from the inside to the surface in the reinforced sample, suggesting that the formation of the compressive layer is due to the reduction expansion only on the surface. Depth profile of XPS and TG-MS showed that only Gd added ceria is difficult to be reduced, which is considered to be related to strength optimization temperature.

Rapid industrialization and increasing electricity demand have highlighted the urgency to reduce energy losses in power generation, accounting for over 60% of global inefficiency. Thermoelectric materials are pivotal for improving energy conversion in high-performance systems. We synthesized La₅SrCu_6−xFe_xO_15−δ samples via solid-phase reaction to study elemental substitution effects on thermoelectric properties. The performance was evaluated by the dimensionless figure of merit ZT = TS²σ/κ, integrating the Seebeck coefficient (S), electrical conductivity (σ), and thermal conductivity (κ). Our results show Fe substitution significantly changes structural, electronic, magnetic, and thermoelectric properties of La₅SrCu₆O_15−δ compound. Fe dopants improve ZT, particularly at higher temperatures, highlighting the potential application on material properties.

Anisotropic shrinkage of powder compacts is often observed in sintering process. Although controlling the shape and size of the sintered body is important to reduce manufacturing cost, it is difficult to understand the factors affecting anisotropic behavior only by experimental observation. In the present study, two-dimensional numerical simulation for sintering process of elliptical particles is performed with changing particle alignment and orientation by using a combined phase-field method (PFM) and discrete element method (DEM). The effects of the size of inter-particle contact plane, the sintering force, and the pore configuration on sintering anisotropy are examined. According to the calculated results, anisotropic shrinkage appears depending on the particle arrangement. The elliptical particles oriented horizontally enhance the horizontal shrinkage. The inter-particle contact in vertical direction reduces the vertical shrinkage. The shrinkage behavior of compacts of elliptical particles can be basically explained by considering the combination of the sintering stress and the size of inter-particle contact plane, except the case of arrangement with largely elongated pore structure.

To clarify the anomalous behavior of magnetization of Zr₂Co₁₂P₇, we synthesized solid solution systems Zr_2−xNb_xCo₁₂P₇ and Zr_2−yY_yCo₁₂P₇ and studied their magnetism. In addition to x = 2 and y = 2, we successfully obtained polycrystalline samples in a single phase in 0 < x < 1 and 0 < y < 1. The Y-substitution did not affect the Curie temperature (T_C), while the Nb-substitution decreased T_C from 150 K to 30 K. The electron doping from Nb or local deformation may cause the decrease of T_C. The low-temperature plateau in the temperature dependence of the magnetization expands to a higher-temperature region by the Nb-substitution. A comparison of the simulation in the two-magnetic-sublattice model and experimental results showed that the magnetic moment of Nb coupled to the ferromagnetic internal field stronger than that of Zr. Qualitative agreement between the simulation and the experiment indicated that d electrons of X are localized, and their magnetic moment couples to the ferromagnetic internal field as the case of 4f electrons of lanthanoids.

Mo₂NiB₂-Ni cermets, a type of boride-based cermet, exhibit attractive mechanical properties such as high hardness and good wear resistance. However, the mechanical properties of these cermets have predominantly been evaluated at room temperature. In this study, three-point bending tests were conducted at high temperatures to investigate the mechanical properties and fractography of Mo₂NiB₂-Ni cermets. A ternary Mo₂NiB₂-Ni cermet was prepared using a calcination process to synthesize Mo₂NiB₂ before sintering. The calcination process resulted in finer and more uniform Mo₂NiB₂ particles, enhancing the microstructure. Consequently, hardness and transverse rupture strength (TRS) were improved. Three-point bending strengths were measured for samples measuring 4.0 × 3.0 × 24 mm at temperatures up to 800°C in an argon environment, using silicon carbide jigs with a 16 mm span. The results indicated that TRS remained approximately constant at about 1.6 GPa up to 500°C but decreased sharply above 600°C, reaching about 0.12 GPa at 800°C. This decrease was attributed to the softening of the nickel binder phase, which adversely affected the TRS.