X-ray powder diffraction studies and bond-valence analysis of Hg2Sb2O7

The crystal structure of Hg2Sb2O7 has been refined using X-ray powder diffraction technique. Hg2Sb2O7 crystallizes in the cubic pyrochlore structure type, space group Fd3¯m, with the lattice parameter a = 10.3525(5) Å, Z = 8, Dc = 9.060(1) g/cm3. The Rietveld refinement procedure was stopped when the intensity residual RB = 3.25% had been reached.In the bond-valence analysis of the crystal structure of Hg2Sb2O7, the values of the bond-valence parameters reported for the Sb5+/O2− ion pair have been found to be doubtful. Using the new calculation scheme, the improved bond-valence parameters for the Sb5+/O2− ion pair (r0 = 1.908 Å and b = 0.409 Å) have been derived from the crystal structure of Sb2O5.