Pentalead tris(vanadate) iodide, a defect vanadinite-type compound

Abstract

A single crystal of Pb 9.85 (VO 4 ) 6 I 1.7 was grown at 1073 K from a mixture of lead vanadate and lead iodide. The structure is of the apatite type with a deficiency of lead iodide. The Pb atom is distributed equally in sites I and II of apatite. The Pb 2+ lone pair induces displacements of the Pb, O and I atoms out of their apatite sites. The apatite structure is preserved by an 'under-stoichiometry' of lead iodide, which allows the distortions to relax.