The Crystal Structures of the Binary Mixed Valence Compound Bi(III)3Bi(V)O7 and Isotypic Bi3SbO7 as Determined by High Resolution X-Ray and Neutron Powder Diffraction

The crystal structure of three tetragonal VxZr1-xO2 solid solutions, with x=0.025, 0.05, and 0.075, prepared by heating dried gel precursors at 450°C in air atmosphere, have been determined by Rietveld refinement on the basis of powder X-ray powder diffractometer data. They contain V4+ cations surrounded by eight oxygens, four at a distance between 2.079 and 2.093 ? and another four at longer distances between 2.369 and 2.348 ?. The estimation of the crystal average oxygen position from the Xray lattice parameter of VxZr1-xO2 conform with the relationship proposed by Howard et al. (J. Am. Ceram. Soc. 81, 241 (1998)).