Commercial-grade Powder Research Articles

Photocatalytic Performance of Ball-Milled Anatase/Rutile Mixed Phase TiO<sub>2</sub> Composite Powders

Mixed-phase anatase/rutile titanium dioxide (TiO2) composite powder is an important material due to the unique properties of photocatalytic activity that is higher than that of the only single anatase or rutile phase. In this study, the anatase/rutile mixed phase TiO2 composite powders were prepared by ball milling of TiO2 commercial grade powders. Effect of the anatase/rutile phase ratio and milling time on photocatalytic performance were investigated. The sample phase ratio is evaluated using X-ray diffraction (XRD) meanwhile the composite morphology is characterized using field emission scanning electron microscope (FE-SEM). The overall results revealed that the mixed-phase anatase/rutile provided significant enhancement in photocatalytic performance comparing to only anatase or rutile single phase. In addition, this ball-milling technique is considered as an effective process and cost-effectively on energy saving suitable for preparing anatase/rutile mixed-phase TiO2 for photocatalytic application.

Comparison of Grain Structure, Electrical and Magnetic Properties of BaTiO3 and Ni0.5Zn0.5Fe2O4 Ceramics Sintered Using Microwave and Conventional Techniques

BaTiO3 (BT) and Ni0.5Zn0.5Fe2O4 (NZF) ceramic disc specimens were prepared using commercial grade powders sintering by conventional (CV) and microwave (MW) sintering techniques. In both the sintering techniques the set sintering temperatures were in the range of 850 °C to 1000 °C and time from 0.5 to 2 h. Structure, microstructure, dielectric, ferroelectric and magnetic properties have been compared for the as sintered BT and NZF ceramic specimens. Comparatively large grain size and higher density observed for the samples sintered at same temperature and shorter holding time using microwave. Magnetic properties of the NZF samples sintered using MW at a temperature of 950 °C show a higher saturation magnetization (Ms) value of 88 emu/g.

Direct Reduction of Vanadium Oxide in Molten CaCl2

A process consisted of electrolysis of CaO in the molten CaCl2 and of calciothermic reduction was applied to prepare metallic vanadium directly from V2O3. The fine metallic powder containing 1860 mass ppm oxygen was successfully obtained using 0.5mol%CaO-CaCl2 melt for 10.8 ks at 1173 K. The oxygen level from the oxide fitted with the demand for hydrogen storage application, but it remained nearly constant even when the twice electricity was supplied. The commercial grade powder contained 1.48% oxygen was, however, well deoxidized to 10 ppm. The large amount of by-product, CaO, due to reduction and the large surface area of the fine particles are the possible reasons of high oxygen content in the reduced powder.

Processing of Lithium Zirconate for Applications in Carbon Dioxide Separation: Structure and Properties of the Powders

Lithium zirconate, Li2ZrO3, has been reported as a candidate material for high‐temperature CO2 separation. The reaction of Li2ZrO3 with CO2 is extremely fast, and the material can store significant quantities of CO2 at high temperature. The reacted CO2 can be regenerated by thermal cycling. Alternatively, a membrane system might be developed based on the reversible reaction process. For absorption and membrane separation, the particle size, crystal structure, and state of agglomeration of the Li2ZrO3 powders are important. Therefore, we have synthesized Li2ZrO3 using sol‐gel procedures and compared its properties with powders made via a powder‐mixing route and a commercial‐grade powder. The morphologic and structural characteristics of the powders and their CO2 absorption properties are discussed.