Single-phase powders of LaMnO₃ and LaCoO₃, lanthanum-based perovskites, were synthesized using the citric acid combustion method. The surface concentration of La in the obtained powder was higher in LaCoO₃ than in LaMnO₃. These samples decomposed 2-naphthol in water in the dark. The decomposition reaction is attributed to the Mars–van Krevelen (MvK) mechanism because of the temperature dependence, activation energy, valence change during the reaction, and the amount of ion elution into water. A disproportionation reaction was confirmed for Mn in LaMnO₃. Both samples exhibited antibacterial and antiviral activity against Escherichia coli, Staphylococcus aureus, bacteriophage Qβ, and bacteriophage Φ6. The antibacterial activity was higher than the antiviral activity. LaCoO₃ tended to have higher antibacterial and antiviral activity than LaMnO₃ had. Results show that these materials had less ion leakage than that reported earlier for La₂Mo₂O₉.

In this study, we investigate the phase transitions of a promising perovskite niobate, RbNbO₃, by synchrotron X-ray diffraction, differential scanning calorimetry, and dielectric property measurements. This compound shows a first-order orthorhombic–tetragonal phase transition at 519 K and does not undergo a transition to a rhombohedral phase down to 5 K. Notably, the spontaneous polarization of the orthorhombic phase is larger than that of a well-studied isostructural perovskite niobate, KNbO₃.

Room-temperature (RT) epitaxial growth of ZnO thin films on flexible cyclo-olefin polymer (COP) substrates coated with the exfoliated β-Ga₂O₃(100) single crystal thin sheets as a seed layer was investigated using the pulsed laser deposition technique. Scanning electron microscopy (SEM) observations and X-ray diffraction (XRD) measurements demonstrated that c-axis-oriented epitaxial ZnO(0001) thin films were obtained at RT on the exfoliated β-Ga₂O₃(100) seed layer bonded to the COP substrate. Also, the epitaxial relationship between the ZnO thin films and β-Ga₂O₃(100) seed layer was ZnO(0001)/β-Ga₂O₃(100) with ZnO[1120] ∥ β-Ga₂O₃[010] and ZnO[1100] ∥ β-Ga₂O₃[001]. The optical transmittance of the thin film, including the seed layer was more than 80 % in the visible light region. The optical band gap and the electrical resistivity of the ZnO thin film were estimated to be about 3.4 eV and about 2.1 × 10⁻³ Ω cm at RT, respectively.

SrO-terminated terraces were formed along TiO₂-terminated step edges by annealing (001) surfaces of SrTiO₃ single crystal originally with step-terrace structure fully terminated at TiO₂ atomic layer. The prepared step-terrace structure with the two different terminations were visualized in a wide field of view using scanning electron microscopy (SEM) under a low acceleration voltage of 1 kV and a short working distance of 2 mm. The different termination was clearly identified by an in-column secondary electron detector even in the wide-field region with dimensions of 30 × 30 µm². As results, the uniformity of the step-terrace structure was found to be limited only at a localized area. The wide-field observation revealed that there exist many “step-defects” such as pinning of the step lines and wandering so large that it goes around to an opposite side. Step-defects were present in at least several for 30 × 30 µm² sized observation areas with a probability of about 60 %.