Cu₂ZnI₄ (CZI) is a non-perovskite-type iodide that has a zincblende-derived layered structure. Since the identification of CZI in the late 1980s, the thin film synthesis and optoelectronic properties of this compound have not ever been reported. We expect CZI to be a potential optoelectronic material because several Cu-based halides are excellent optoelectronic semiconductors. In this study, we synthesized CZI thin films and investigated their optical properties. Single-phase CZI polycrystalline films were obtained for the first time using vacuum evaporation. These films were highly transparent in the visible region, and optical absorption analysis revealed CZI to be a widegap compound with the bandgap of 3.1 eV. Furthermore, the CZI films exhibited violet-light photoluminescence originating from excitonic transitions even at room temperature. Our findings suggest that CZI is a potential candidate for a light-emitting material.

Octacalcium phosphate (OCP) crystals have a layered structure into which various carboxylate ions can be incorporated. Recent studies have been conducted to incorporate aromatic carboxylate ions into OCP to impart fluorescence. However, the fluorescent properties of OCP with incorporated isophthalate ions have not been investigated. In this study, we synthesized OCP with incorporated isophthalate ions, and investigated its fluorescence behavior. The interplanar spacing of OCP was expanded from 1.88 to 2.32 nm by incorporation of isophthalate ions. The absorption peaks derived from the incorporated isophthalate ions were detected by Fourier transform infrared spectroscopy. We found that the obtained OCP with incorporated isophthalate ions emitted strong fluorescence at 315 nm with excitation light at 280 nm and emitted weak fluorescence at 380 nm with excitation light at 313 nm. The characteristic feature of this fluorescent OCP was ultraviolet light emission, whereas the previously reported fluorescent OCPs emitted visible light. The results of this study are worthwhile for the design of OCP-based materials with various fluorescent properties.

High-yield production of high-purity, disperse, ultrafine, and equiaxed gamma-alumina (γ-Al₂O₃) nanoparticles with narrow size distributions are essential for their applications. However, the synthesis of γ-Al₂O₃ nanoparticles by calcination of alumina precursors usually results in severe aggregates. In our present work, commercial γ-Al₂O₃ particles with an irregular shape, large size, and severe aggregates were directly ball-milled. The milled powders were subsequently corroded with hydrochloric acid to obtain γ-Al₂O₃ nanoparticles. The γ-Al₂O₃ nanoparticles obtained are dispersed without aggregates, equiaxed in shape, and ultrafine with a mean particle size of 6.2 nm. The disperse γ-Al₂O₃ nanoparticles are with high purity (99.994 %, mass per cent) and yield. Then γ-Al₂O₃ nanoparticles were separated by fractionated coagulation to narrow their size distribution. After coagulation separations, γ-Al₂O₃ nanoparticles with mean particle sizes of 4.8, 6.6, and 7.7 nm and respective size distributions of 2–9, 2–12, and 2–15 nm were acquired. This high-yield preparation process for γ-Al₂O₃ nanoparticles is simple and scaled up. Furthermore, using commercial γ-Al₂O₃ powders as starting material, disperse, and equiaxed α-Al₂O₃ nanoparticles with a mean particle size of 7.6 nm and purity of 95.98 % (mass per cent) were also prepared by ball milling at a higher ball-to-powder weight ratio of 60:1 and acid corrosion.

The Raman and infrared (IR) spectra for the alkaline earth metaphosphate crystals with chains were assessed by density functional theory (DFT) calculations. The assignments of peaks of the DFT calculated Raman and IR spectra were consistent with reported assignments of phosphate crystals and glasses except for the assignment of the peaks around 1100 cm⁻¹ of the calculated IR spectra. Peaks around 1100 cm⁻¹ of IR spectra for phosphate crystals and glasses have been assigned to asymmetric stretching vibrations of bonds between phosphorus atoms and non-bridging oxygens (NBO) of Q¹ units. However, the calculated IR spectra showed that symmetric stretching vibrations of P–NBO bonds and asymmetric stretching vibrations of –P–O–P– bonds of Q² units also result in peaks around 1100 cm⁻¹. In addition, the calculated Raman spectra showed a strong correlation between cation field strength and the Raman shift of intense peaks assigned to symmetric stretching vibrations of P–NBO bonds of Q² units.

In present work, structurally controlled porous hydroxyapatite ceramics are fabricated via a novel and facile gel-casting process with trace addition of cellulose nanofiber (CNF). The pore structure with respects to pore size, shape and open/close porosity is selectively controlled by altering the addition amount of CNF and surfactant, as well as forming time. The origin of pore structure controlling is systemically investigated in the point view of chemical/physical interaction between ceramic powder, CNF as well as dispersant, assisted by detailed characterizations as X-ray computer tomography observation, viscosity analysis, and z-potential analysis. Fabricated porous ceramic bodies exhibit superior low thermal conductivity which opens a new avenue for the wide applications of hydroxyapatite ceramics.

Single crystals of a garnet-type oxide Ca_0.8Y_3.4Zr_0.8Ga_3.0O₁₂ [cubic, a = 12.6404(2) Å, Ia-3d] were synthesized by heating a compact mixture of CaCO₃, Y₂O₃, ZrO₄, and Ga₂O₃ powders at 1600 °C for 1 h in air. Crystal structure analysis by the conventional X-ray diffraction (XRD) method could not distinguish atoms of adjacent Y and Zr elements. The Y occupation at the 24c and 16a sites of Wyckoff positions in the crystal structure was revealed by δ-synthesis with anomalous X-ray scattering. The formula was determined to be (Y_0.6296(3)Ca_0.2440(2)Zr_0.1261(2))₃(Y_0.7556(5)Ca_0.0340(2)Zr_0.2109(2))₂(GaO₄)₃.