Using hydrothermal processing, we prepared a cerium bismuth solid solution oxide ((Ce_0.8,Bi_0.2)O_2−δ, CBO) and a cerium lanthanum solid solution oxide ((Ce_0.8,La_0.2)O_2−δ, CLO). The resultant powders possessed fluorite-type crystal structure. They also decomposed 2-naphthol in water in the dark. From their valence change and temperature dependence, we infer that the Mars–van Krevelen (MvK) mechanism of Ce contributes to this decomposition activity. These materials showed higher decomposition activity under visible light. Modification of CoO_x onto these materials enabled an apparent bandgap decrease and the MvK mechanism of Ce and Co, which led to higher decomposition activity in the dark and under visible light. The CBO activity was higher than that of CLO on the decomposition of 2-naphthol in water, but the CLO antiviral activity was higher than that of CBO. Results suggest that the CLO antiviral activity results from virus deactivation by direct contact with the powder surface.

A few GPa-order high-pressure impedance measurement was performed by utilizing an indentation method, which is often used to evaluate mechanical characteristics, and the alternating current (AC) impedance method simultaneously. We succeeded in estimating the activation volume (ΔV = 3.2 cm³/mol) for O²⁻ ion conduction of YSZ with a single sweep of load at 0.25 N/s up to 25 N. Such a quick and easy method for determining ΔV is completely new that has not been proposed so far.

Alumina, mullite, and cordierite powder were added to a whiteware porcelain slurry and sintered at 1280 °C to investigate the correlation between porcelain composition and strength. The X-ray diffraction patterns of the sintered bodies show that no new phase was formed, and that the added material remained intact. Except for the sample group to which cordierite was added, the strength increased as the additive content increased. A Rietveld quantitative analysis indicated that the amorphous phase decreased with increasing additional alumina and mullite content, while the amorphous content remained constant regardless of the additional cordierite content. The decrease in the amorphous content increased the strength of the porcelain, which, in the case of the sample with 15 wt.% alumina, increased by 57 %. The dramatic increase in strength is attributed to the increase in residual stress due to the difference in the thermal expansion coefficient between the alumina and the amorphous phase, as well as the increased formation of mullite by the addition of alumina.

Titanium oxide films were prepared from peroxotitanium complex aqueous solution containing a peroxo complex of vanadium, molybdenum or tungsten of 2, 5, 10 mol % by heating at 200 °C for the purpose of suppressing the photocatalytic activities that may be developed by crystallization during long-term use as a prevention film against potential-induced degradation (PID) of crystalline silicon (c-Si) photovoltaic (PV) module. The films containing those dopants crystallized to anatase by hydrothermal treatment at 100 °C for 15 h as an acceleration test, but hardly showed any photocatalytic activity. According to the lattice constants, X-ray photoelectron spectroscopy analyses and UV–visible light reflection spectra, it was estimated that vanadium (V), molybdenum (VI) and tungsten (VI) were substituted with titanium (IV) in titanium oxide heated at low temperature of 200 °C. The titanium oxide films containing the dopants of 2 mol % were coated at 200 °C onto the rear side of front cover glass with 200 nm thickness. No significant PID was observed in the c-Si PV modules based on the film-coated glass by a PID test by applying −1000 V at 85 °C for 2 h.