Crystal structures of Zn2GeO4 cubic/tetragonal spinel and Zn2SiO4 modified spinel phases

Abstract

Crystal structures of the cubic and tetragonal spinel phases of Zn2GeO4 and the modified spinel phase of Zn2SiO4 were refined by Rietveld analysis of synchrotron powder X-ray diffraction data. The Zn2GeO4 cubic spinel phase was found to have an inverse spinel configuration. The Zn2WGeO4 tetragonal spinel phase is isostructural to Zn2TiO4, where half of Zn occupies the tetrahedral site, and the remaining Zn and Ge are ordered in two octahedral sites. In the modified spinel phase of Zn2SiO4, Zn occupies the octahedral sites. Independent individual cation-oxygen distances in the Zn2GeO4 tetragonal spinel and Zn2SiO4 modified spinel phases were calculated using the bond valence repartition method, and are in reasonable agreement with the refined structures.