Although TiNb₂O₇is regarded as a material with high application potential in lithium-ion batteries (LIBs) and solid-oxide fuel cells (SOFCs), it has been difficult to find suitable cost-effective conditions for synthesizing it on a commercial scale. In this study, TiNb₂O₇compounds were synthesized by a solid state synthesis process. For stoichiometrically precise synthesis of the TiNb₂O₇phase, the starting materials, TiO₂and Nb₂O₅were taken in a 1:1 molar ratio. Activation energy and reaction kinetics of the system were investigated at various synthesis temperatures (800,1000,1200, and 1400°C) and for various holding durations (1,5,10, and 20 h). Furthermore, change in the product morphology and particle size distribution were also evaluated as a function of synthesis temperature and duration. Additionally, quantitative phase analysis was conducted using the Rietveld refinement method. It was found that increases in the synthesis temperature and holding time lead to increase in the mean particle size from 1 to 4.5 μm. The reaction rate constant for the synthesis reaction was also calculated.

Developing inexpensive and rapid fabrication methods for high efficiency thermoelectric alloys is a crucial challenge for the thermoelectric industry, especially for energy conversion applications. Here, we fabricated large amounts of p-type Cu_0.07Bi_0.5Sb_1.5Te₃ alloys, using water atomization to control its microstructure and improve thermoelectric performance by optimizing its initial powder size. All the water atomized powders were sieved with different aperture sizes, of 32–75 μm, 75–125 μm, 125–200 μm, and <200 μm, and subsequently consolidated using hot pressing at 490 °C. The grain sizes were found to increase with increasing powder particle size, which also increased carrier mobility due to improved carrier transport. The maximum electrical conductivity of 1457.33 Ω⁻¹ cm⁻¹ was obtained for the 125–200 μm samples due to their large grain sizes and subsequent high mobility. The Seebeck coefficient slightly increased with decreasing particle size due to scattering of carriers at fine grain boundaries. The higher power factor values of 4.20, 4.22 × 10⁻³ W/mk² were, respectively, obtained for large powder specimens, such as 125–200 μm and 75–125 μm, due to their higher electrical conductivity. In addition, thermal conductivity increased with increasing particle size due to the improvement in carriers and phonons transport. The 75–125 μm powder specimen exhibited a relatively high thermoelectric figure of merit, ZT of 1.257 due to this higher electric conductivity.

Contact materials in high-voltage vacuum interrupters require properties such as high conductivity, density and hardness to minimize arc heat damage. In this study, Cu–Cr–Mo alloy contact materials were examined for their usage as high-voltage contact materials. Ball milling was performed after analyzing the raw materials of the Cu, Cr and Mo powders. A green compact was produced using high pressure with a mixed powder. Subsequently, the composite was produced by sintering via the temperature and infiltration method according to the Cu content in the green compact. The composite sintering method produced a density of 8.55 g/cm³ (relative density 93%), a hardness of 217 HV and an electrical conductivity of 40.7% IACS at 1200 °C. The composite of 10 wt.% Cu produced by the Cu infiltration method exhibited a density of 8.7 g/cm³ (relative density 94%), hardness of 274 HV and electrical conductivity of 39 IACS% at 1300 °C. The measurements of the physical properties of our newly established method demonstrated a new possibility of using the Cu–Cr–Mo alloy as a contact material for high-voltage vacuum interrupters.

Commercial production of titanium involves chlorination using chlorine gas that can be converted to hydrochloric acid by atmospheric moisture and is hazardous to human health. In the titanium production process, self-propagating high-temperature synthesis is one of the process to directly reduce titanium dioxide. In this work, titanium powder was prepared by self-propagating high-temperature synthesis using titanium dioxide as the starting material and magnesium powder as a reducing agent. After the reaction, magnesium and magnesium oxide by-products were then removed by acid leaching under different leaching conditions, leaving behind pure Ti. During each leaching condition, the temperature of the leaching solution was carefully monitored. After leaching, the recovered titanium in the form of a powder was collected, washed with water and dried in a vacuum oven. Detailed compositional, structural, and morphological analyses were performed to determine the presence of residual reaction by-products. It was found that leaching in 0.4 M hydrochloric acid followed by second leaching in 7.5 M hydrochloric acid is the optimum leaching condition. Furthermore, it was also noticed that total volume of solution in 0.4 M hydrochloric acid leaching condition is advantageous to maintain uniform temperature during the process.