A New Structural Model for Pb-Deficient PbWO4.

Abstract A previously reported structure proposal for Pb-deficient PbWO4 (Pb7W8O32−x, space group P4/nnc) could be rejected based on neutron powder diffraction data. A new model in agreement with X-ray and neutron diffraction data is proposed (tetragonal, tP48, space group P-4-h10g2dcba, a=7.7208(1), c=12.0417(2) A). It is a superstructure of the scheelite type with partial vacancies on a one-fold lead site, leading to the composition Pb7.5W8O32.