We investigated a silver carboxylate synthesis method that works by irradiating ethanol containing silver oxide and carboxylic acid in two steps using both low- and high-frequency ultrasonic waves. Specifically, high aspect ratio silver carboxylate samples were synthesized by irradiating ethanol containing silver oxide and carboxylic acid low-frequency ultrasonic waves for a short time and then further irradiating them with high-frequency ultrasonic waves for a longer period of time. The strong physical actions produced by the low-frequency (44 kHz) ultrasonic waves promoted fragmentation and degradation of the produced silver carboxylate particles, while the high-frequency (1.0 MHz) frequency ultrasonic waves promoted the growth of the produced silver carboxylate particles via chemical actions. Using the synthesized precursor, we then succeeded in producing silver nanowire transparent conductive films using a simple process. The film performance improved with higher aspect ratio precursors.

We fabricated neutron detection glasses, Tb³⁺-doped CaO–Al₂O₃–B₂O₃ glasses, including ¹⁰B-enriched (¹⁰B glass) and ¹¹B-enriched (¹¹B glass) glasses. The glasses were irradiated with X-rays, heavy particles, or neutrons and their thermoluminescence (TL) properties were investigated. The TL properties after X-ray or heavy particle irradiation were the same for the ¹⁰B and ¹¹B glasses. Meanwhile, after neutron irradiation, the TL properties of the ¹⁰B and ¹¹B glasses were significantly different. The TL intensity of the ¹⁰B glasses was higher than that of the ¹¹B glasses, and the TL peak intensity of ¹⁰B (n, α) reaction had good linearity in the irradiation range of 10⁹–10¹³ neutrons/cm².

In this study, we aimed to improve apatite-forming ability of titanium (Ti) and its alloys, Ti–15Mo–5Zr–3Al, Ti–12Ta–9Nb–6Zr–3V–O, Ti–6Al–4V, and Ti–22V–4Al. The surfaces of Ti and its alloys were treated by the doubled sandblasting process using ceramic grinding particles with 14.0 and 3.0 µm for average particle size. The Ti and its alloys were immersed in the alkaline simulated body fluid (SBF) which was adjusted at higher pH than that in the physiological SBF and were heated in the alkaline SBF by electromagnetic induction. By this treatment, apatite nucleation was promoted near the surface of the substrates and apatite nuclei were precipitated in the pores of the substrates. By immersing in the physiological SBF to test apatite-forming ability, hydroxyapatite was covered the entire surfaces of the Ti and its alloys within 1 day and high apatite-forming ability was shown. The doubled sandblasting process firstly using larger grinding particles and secondly using smaller ones was most effective to increase the surface roughness of the substrates. Average adhesive strength of the hydroxyapatite layer formed in the physiological SBF increased, which depended on the increase of the surface roughness. These results indicated that sandblasting condition was an important factor to improve mechanical interlocking effect related to the increase of the surface roughness and that the doubled sandblasting process had a possibility to be one of the candidates of the treatment to solve this problem.

The variation in the crystal structure of Ln₂Ni_1−xCu_xO_4+δ, which has great potential as a new cathode material for solid oxide fuel cells, based on the type of Ln (La, Pr, Nd, Sm, Eu, and their solid solution), was investigated. For Ln with ionic radius larger than 1.21 Å (1 Å = 0.1 nm), a single-phase K₂NiF₄ structure called T-phase was prepared for 0.0 ≤ x ≤ 1.0. For Ln with ionic radius between 1.21 and 1.15 Å, the crystal structure changed from single T-phase to single Nd₂CuO₄ structure called T′-phase, through the mixture of T-phase and T′-phase, along with increasing Cu content. The range of Cu content, in which the mixture phase was obtained because of the miscibility gap, increased with the decreasing size of Ln. The single T-phase was never prepared for Ln with ionic radius below 1.15 Å. Rough tendencies were observed, indicating that the single T-phase was obtained or was not prepared if the tolerance factor was above or below 0.865, respectively. The mixture of T-phase and T′-phase was obtained because of the miscibility gap by decreasing the tolerance factor slightly below about 0.865. The T-phase was never generated by decreasing the tolerance factor any further. The change of the crystal structure by Cu content and kind of Ln can also be explained by using Jahn–Teller effect of Cu²⁺ ion.

Rutile-type TiO₂ was modified with NiO and CeO_x using chemisorption calcination cycle method. Then the decomposition activity of 2-naphthol in water was evaluated in the dark or under visible light at 50°C. Little difference was found in the specific surface area or crystal phase before and after modification. The NiO modification decreased the apparent bandgap and provided photocatalytic decomposition activity under visible light. Results suggest that the formation of a Ti–O–Ni interfacial bond yielding a surface d sub-band plays an important role in this increased activity. Although the NiO-modified TiO₂ possessed decomposition activity only under visible light, additional modification of CeO_x onto the material enabled decomposition of 2-naphthol in water in the dark at 50°C. The dark activity was attributed to the Mars–van Krevelen mechanism of Ce in CeO_x. The NiO-modified TiO₂ exhibited high antibacterial activity against Escherichia coli and Staphylococcus aureus under visible light at room temperature.

This study describes the investigation of photoluminescence (PL) and afterglow properties of samarium ion (Sm³⁺)-doped zirconia and the comparison with those of pure zirconia. The pure sample exhibits bluish PL and afterglow upon excitation by ultraviolet light, whereas white-to-reddish PL and white afterglow are detected by means of visual observation and spectroscopic measurement in the doped samples. It is therefore suggested that the Sm³⁺-doped zirconia is applicable to a temperature-sensing probe for the human body because it shows afterglow PL in the near-infrared “biological window” region.

Hafnium oxyphosphate was prepared as a novel photocatalyst for hydrogen production from water. Here, Hf⁴⁺ with d⁰ electronic configuration was selected as the constituent cation, because efficient photocatalysts generally contain d⁰ or d¹⁰ metal cations. In addition, most phosphates are reported to have high photoreduction ability of water due to their wide bandgap compared to oxides. By using Hf₂O(PO₄)₂, hydrogen gas was generated from water under the ultraviolet light irradiation, while a simple hafnium oxide, HfO₂, did not show a hydrogen evolution ability. The hydrogen production rate of Hf₂O(PO₄)₂ was estimated to be 800 µmol·h⁻¹. Also, oxygen gas evolution was observed for Hf₂O(PO₄)₂.

Detection of nitrite-ion has become very important for various industrial fields due to its wide application range such as food additives and a rust preventive agent for steels. In this study, we attempted at developing an advanced method to produce layered perovskite-type cuprates based thick-film device for highly sensitive electrochemical sensor for nitrite-ion with a capacity of wide concentration range. Here, layered perovskite-type oxide powders could be synthesized by a polymer precursor method which was deposited on alumina supports with gold electrode by an electrophoretic deposition method. The sensor performance was measured by an amperometric method for nitrite-ion detection. It was found that the Gd₂CuO₄-based electrode showed fast and good linear responses to nitrite-ion for a wide range of concentration.

Ultra-high spatial resolution better than 0.5 Å has been achieved in aberration-corrected scanning transmission electron microscopy (STEM). By combining such an ultra-high resolution STEM with a differential phase contrast (DPC) imaging technique, we can now directly visualize the electric field distribution inside individual atoms in real space. The atomic electric field, i.e., the field between the nucleus of the atom and the electron cloud that surrounds it, contains information about the atomic species and charge redistribution due to chemical bonding. In this review, the current status of the development in atomic-resolution DPC STEM and its future direction is discussed.

The synthetic technique to control hierarchical structure is essential for the development of highly functional materials. In this article, we review the challenges involved in creating new calcium phosphate–polymer composites as artificial bone that extends beyond autologous bone, by combining hierarchical structural control at the macro, micro, and nano levels. Gel-mediated processing is a powerful method for preparing macroscopically homogeneous calcium phosphate–polymer composites, and the biomimetic approach is effective for controlling the microscopic morphologies of calcium phosphate particles formed in polymeric hydrogel matrices. Octacalcium phosphate (OCP), which is a member of the calcium phosphate family, has a layered structure. Controlling the nanoscopic structure of OCP through the incorporation of organic molecules into the interlayers of its crystal lattice is a promising approach for adding new functionalities and improving the biological properties of composite materials.

First-principles calculations were used to analyze relationship between elastic stiffness and thermal conductivity of Eu₂Hf₂O₇ and Gd₂Hf₂O₇ pyrochlore oxides. Eu₂Hf₂O₇ demonstrated mechanical properties inferior to Gd₂Hf₂O₇. Eu₂Hf₂O₇ and Gd₂Hf₂O₇ belong to quasi-ductile ceramic materials because their G/B ratios are below 0.571 and because of their positive Cauchy pressure values. Thermal conductivity values of Eu₂Hf₂O₇ and Gd₂Hf₂O₇, equal to 1.66 and 1.62 W/(m·K) are below that of yttria stabilized zirconia. Thus, Eu₂Hf₂O₇ and Gd₂Hf₂O₇ pyrochlores are promising as thermal barrier coatings for high-temperature applications, for example, in gas turbine engines.

The mesoporous titanium vanadium nitride (TiVN) powders were prepared by sol–gel method combined with ammonia reduction nitridation process. The obtained powders were non-stoichiometry TiVN solid solution phase with different valence of Ti and V ions as determined by X-ray diffraction and X-ray photoelectron spectroscopy. The energy dispersive X-ray spectroscopy results showed that the N, Ti and V elements were homogeneously distributed in the TiVN powders. Scanning electron micrographs revealed that the diameter of TiVN powders was in the range of 1–2 µm. It was found that the TiVN powders possessed BET surface area of 24.3 m²/g and average pore size of 19.8 nm. A maximum specific capacitance of 231 F/g was tested by Galvanostatic charge–discharge and retained 99.4% of initial capacitance after 2000 cycles. While the capacitance of TiN and VN powders were only 93 and 221 F/g. Cyclic voltammetry and Electrochemical impedance spectroscopy measurements were also performed. The intrinsic resistance of the mesoporous TiVN powders electrodes was 0.9 Ω, which was smaller than that of the TiN (1.1 Ω) and VN (1.1 Ω). It indicated that the mesoporous TiVN powders with the uniform distribution of each element could also effectively improve the electrochemical properties of electrodes compared with TiN and VN powders.

Zinc oxide (ZnO) micro/nanocrystals were grown via thermal evaporation of ZnO and Al powder mixture in air at atmospheric pressure. The effect of Al on the morphology and luminescence properties of ZnO crystals was investigated. The spherical shaped ZnO nanocrystals with the sizes of 150–230 nm were formed at 800°C. As the growth temperature increased from 800 to 900 and 1000°C, the morphology of ZnO micro/nanocrystals was changed to belt and plate shape, which indicated that the vertical growth of the crystals was suppressed with the growth temperature. The belt-like crystals had widths of 80–500 nm and lengths of several to several tens of micrometers. The plate-like crystals had widths ranging from 0.8 to 1.7 µm. X-ray diffraction patterns revealed that the ZnO had hexagonal wurtzite crystal structure. A strong ultraviolet emission centered at 380 nm was observed in the cathodoluminescence spectra of all the as-synthesized ZnO crystals.

Porous Co₃O₄ thin films were prepared at low temperatures by two different methods: solution combustion (SC), and decomposition of Co-containing metal organic framework (MOF) thin films. The former method involved spin coating of 2-methoxyethanol solution containing Co²⁺ ions, acetylacetone, and ammonia, followed by calcination in the temperature range from 473 to 773 K. The latter method involved the spontaneous deposition of Co(MeIM)₂ (MeIM = 2-methylimidazol) MOF flat thin films on substrates, followed by decomposition at temperatures higher that 573 K to obtain porous Co₃O₄ thin films. The SC method produced electrochemically active and reversible thin films at a low final processing temperature of 473 K, allowing the deposition of porous Co₃O₄ layers onto polymer substrates. The MOF-decomposition yielded thin films with similar electrochemical activity and reversibility as those of the films obtained by the SC method at a processing temperature of 573 K. In both methods, an increase in the final processing temperature promoted the sintering of the porous structured thin films, leading to the formation of dense structures, which caused a deterioration in the electrochemical activity.

Nickel oxide coated ZnMn₂O₄ nanocomposites were successfully synthesized by two-step method combined hydrothermal reaction and calcination process. The microstructure, morphology and the color mapping of the as-prepared samples were characterized by means of X-ray diffraction, high resolution electronic microscope microstructure, field emission scanning electron microscopy and energy-dispersive X-ray spectrum. The electrochemical performance of the samples were investigated by cyclic volt-ampere (CV), constant-current charge–discharge and electrochemical impedance spectroscopy. The experimental results show that nickel oxide coated ZnMn₂O₄ nanocomposites exhibit weak Ni₂O₃ hexagonal phase besides obvious ZnMn₂O₄ spinel tetragonal structure, the morphologies are uniform polyhedron structure with obvious cladding layer. CV curves exhibit rectangular shape without obvious redox peaks. Nickel oxide coated ZnMn₂O₄ nanocomposites shows better specific capacitance and excellent cyclic stability, and maintains 98.8% of its initial capacitance after 1200 cycles. Nyquist plots of nickel oxide coated ZnMn₂O₄ nanocomposites proving the samples possess lower resistance and ideal electron conductivity.

A microwave hybrid heating method was used for the synthesis of Cr₂AlC powder using two carbon sources of graphite and Cr₃C₂, and tribological behaviour of Cr₂AlC powders was investigated. The purity of Cr₂AlC is sensitive to the synthesis temperature and the starting materials used. For a Cr/Al/C system, Cr₂AlC with a small amount of Cr₇C₃ was synthesised at 1100°C for 3 min. For Cr/Al/Cr₃C₂ system, high purity Cr₂AlC was synthesized at 1050°C for 3 min. Ultrafine Cr₂AlC powder with a grain diameter of less than 500 nm (denoted by u-Cr₂AlC) could be prepared by ball-milling and ultrasonic treatment. The tribological properties of as-synthesised and ultrafine Cr₂AlC powders as an additive in 150SN base oil were evaluated by an MMW-1A four-ball friction and wear tester. The results show that the base oil containing 2 wt % Cr₂AlC presented good tribological performance under a load of 300 N. In addition, the particle size plays an important role in the tribological performance. Ultrafine Cr₂AlC powder shows a better tribological performance than MoS₂ and as-synthesised Cr₂AlC. The improved tribological properties of the u-Cr₂AlC sample could be attributed to the formation of a tribo-film under friction.

Photocatalytic monoliths with hieratical pores ranging from nm to µm, consisting of titanate nanotubes (TNTs), SrTiO₃ nanoparticles, and TiO₂ nanoparticles, are prepared by a hydrothermal reaction of a porous TNT/TiO₂ monolith with Sr(OH)₂. The precursory TNT/TiO₂ monolith is composed of TNTs and TiO₂ (anatase) nanoparticles where the frameworks of the monolith are constructed from interconnected and entangled TNTs. The SrTiO₃ nanoparticles are found to be homogeneously formed on the TNTs. Close contact between SrTiO₃ nanoparticles and TNTs in the porous monolith is considered to benefit an enhancement of photocatalytic activity due to an effective suppression of the electron–hole recombination at the heterojunction.

The yttria-stabilized zirconia precursors of x mol% Y₂O₃/(100 − x) mol% ZrO₂ was successfully synthesized by homogeneous precipitation method by microwave heating. The Raman spectroscopy and Fourier Transform Infrared Spectroscopy (FT-IR) measurements clarified that the precursor contained zirconium hydroxide. The crystallization behaviors of the precursor were investigated by the X-ray diffraction, Raman spectroscopy, FT-IR, and Differential Scanning Calorimetry (DSC) measurements. For the FT-IR measurements only Zr–O bond was appeared at 500°C. By the DSC measurements revealed that the crystallization temperature of the precursor with microwave heating was lower, and the density was higher than that of conventional heating. This advance could cause by microwave technique.

Characteristics of the devitrification of silica glass containing 1000 mass ppm of Cl were investigated. The magnitude of the devitrification was evaluated by the depth at the center of the crystallization area grown by putting a grain of NaCl crystal on a flat polished surface of silica glass plate. The devitrification characteristics were compared with those of various types of silica glasses containing no Cl and various amounts of OH. The slope of devitrification depth in the Arrhenius plot changes abruptly at T_c ≈1000°C; The slope at a temperature higher than T_c of the Cl-containing silica is considerably smaller than those of other silica glasses. This fact indicates that the Cl-containing silica glass is durable to devitrification, especially at temperatures higher than T_c.