Phase Equilibria in the In₂O₃-WO₃ System
Date
2003
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Alfred University. Faculty of Ceramic Engineering. Kazuo Inamori School of Engineering.
Abstract
Uses of materials in the In₂O₃-WO₃ system are far reaching. Applications include gas sensing, catalysts, as well as other potential electrical and optical applications. The subsolidus phase relationships in the In₂O₃-WO₃ system at 800 – 1400°C were studied by x-ray diffraction. Two binary oxide phases – In₂(WO₄)₃ and In₆WO₁₂ – were found to be stable in air over the temperature range of 800 – 1200°C. The structures of the binary oxides were refined using the Rietveld method. Differential thermal analysis data of In₂(WO₄)₃ showed a large exothermic/endothermic peak upon heating and cooling respectively between 260°C and 240°C. The data was interpreted as a phase transition. Higher-resolution diffraction data of In_{2}(WO_{4})_{3} was taken at 310°C (583K) and 225°C (498K). The structure of In₂(WO₄)₃ at 310°C (583K) was refined to the Sc_{2}(WO_{4})_{3} -type Pnca space group. The low temperature phase of In₂(WO₄)₃, x-ray data taken at 225°C (498K), is believed to crystallize in the Fe₂(MoO₄)₃-P 21/a monoclinic space group. Rietveld refinement of bulk powder In_{6}WO_{12} satisfactorily matched single crystal work using the R 3r space group.
Description
Type
Thesis
item.page.format
Keywords
Phase equilibrium, Tungsten oxide, Indium oxide