X-ray Rietveld structure refinement of Sb3O6.5

The crystal structure of Sb 3 O 6.5 has been refined using the Rietveld analysis of X-ray powder diffraction data. The refinement procedure was stopped when the intensity residual R B = 6.1% had been reached. Sb 3 O 6.5 crystallizes in a cubic structure of the defect pyrochlore type, space group Fd -3 m (No. 227), with the lattice parameter a = 10.3024(5) A, Z = 8, D c = 5.701(1) g/cm 3 .