ZrC powders were synthesized by a combined sol–gel and microwave carbothermal reduction method using zirconium oxychloride and citric acid as starting materials. The effects of firing temperature and n(C)/n(Zr) molar ratio on the synthesis of ZrC powders were studied. The results showed that the optimal n(C)/n(Zr) for the preparation of phase pure ZrC powders was 5.0, and the firing temperature required was 1573 K. This synthesis temperature was 200 K lower than that required by using conventional carbothermal reduction method. Microstructures and phase morphologies of as-prepared ZrC powders were examined by using a field emission–scanning electron microscope (FE–SEM) and a transmission electron microscope (TEM), revealing that the grain sizes of ZrC in the samples prepared at 1573 K for 3 h were about 200–300 nm.

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Nickel oxide-based photochromic composite films were fabricated by combining nickel nitrate in methanol solution with a transparent urethane resin. The resulting nickel oxide-based composite film showed a reversible photochromic property that was similar to the electrochromic property in nickel oxide-based films. IR spectra revealed that the valence state of nickel in the composite films changed from “+3” to “+2” under UV irradiation. The Ni-based particles dispersed in the films had sizes of 40–100 nm.

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We show that acetic acid enhances the HPO₄–OH layer structure of octacalcium phosphate (OCP) and hypothesize that the presence of acetic acid is essential for obtaining large-sized highly crystalline OCP with relatively high-temperature (∼65°C) aqueous-solution synthesis methods. The OCP crystal consists of three types of layer structures (apatite-like, transition, and HPO₄–OH). X-ray diffraction (XRD) analysis indicates that increasing acetic acid concentration leads to the development of their greater structure. Infrared (IR) and nuclear magnetic resonance (NMR) spectroscopic measurements indicated development of the highly HPO₄–OH layer-structure. The enhanced layer structure development caused by acetic acid is in contrast to the generally observed decrease in HPO₄–OH layer structure in the presence of –COOH-containing molecules such as citrate and succinate.

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In this study, Si₂N₂O particles intended for use as radiative cooling materials were synthesized by heat-treatment of mixtures of Si and SiO₂ powders in an N₂ atmosphere at 1450°C. The resulting Si₂N₂O particles were used as Si₂N₂O coatings on Al substrates as a radiative cooling device, and these coatings were generated using pulsed electrophoretic deposition. The average difference in temperature from the ambient temperature of the SSRM devices with the film thicknesses of 6.5, 13.2 and 35.2 µm were −0.82, −0.44 and +0.83°C, respectively. A radiative cooling effect was observed for the device with the film thicknesses of 6.5 and 13.2 µm.

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Glasses with the batch composition (Tl₂O₃)_x(SiO₂)_1−x (x = 0.20–0.40) were synthesized by melting a mixture of Tl₂O₃ and SiO₂, and their electrical properties were investigated. It was confirmed that the Tl in the thallium silicate glasses existed in the mono- and trivalent states. The electrical conductivity of the (Tl₂O₃)_x(SiO₂)_1−x glasses increased with an increase in the x value in the range of x = 0.20–0.40. The electrical conductivity of the glass with the batch composition of (Tl₂O₃)_0.40(SiO₂)_0.60 [analyzed composition: (Tl¹⁺₂O)_0.332(Tl³⁺₂O₃)_0.061(SiO₂)_0.607] was 5.0 × 10⁻⁶, 2.4 × 10⁻⁵, and 9.6 × 10⁻⁵ S·cm⁻¹ at 150, 200 and 250°C, respectively.

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