High-Temperature XRD Study and Rietveld Refinement of A2W3O12(A=Y, Er, Ho, Yb) Rare-Earth Tungstate

Abstract:

A2W3O12(A=Y, Er, Ho, Yb) rare-earth tungstate materials were synthesized by solid state method at high temperature. The structures, lattice constants and cell volumes of A2W3O12 were determined by room temperature and high temperature XRD at different temperatures, and their Rietveld refinements were performed by TOPAS software. It is found that Y2W3O12, Er2W3O12 and Yb2W3O12 all possess orthorhombic structure and show negative thermal expansion; whereas Ho2W3O12 has monoclinic structure and shows positive thermal expansion. According to A. W. Sleight prediction, Ho2W3O12 should have large negative thermal expansion, but it shows no negative thermal expansion but large positive thermal expansion coefficient in the present experiment.