Ab-initio structure determination of LiSbWO6 by X-ray powder diffraction

The crystal structure of LiSbWO6 is solved from X-ray powder diffraction data. The cell is orthorhombic (space group Pbcn, Z = 4) with a = 4.6664(1) Ä, b = 17.4435(5) Ä, c = 4.9941(2) Ä. Initial positional parameters for antimony and tungsten were obtained from direct methods applied on 307 reflexions which were derived from a modified Rietveld analysis working without structural model. The structure was refined using Rietveld profile refinement principles ; the final reliability factors (%) are Rx = 2.1, RWP = 6.5. The structure derives from PbO2-α by a tripling of the b axis of PbO2 with a full cationic order, unlike the columbite structure which is related to PbO2-α by a tripling of the a-axis.