New lead vanadium phosphate with langbeinite-type structure: Pb1.5V2(PO4)3

The new lead vanadium phosphate Pb1.5V2(PO4)3 was synthesized by solid state reaction and characterized by X-ray powder diffraction, electron microscopy, and magnetic susceptibility measurements. The crystal structure of Pb1.5V2(PO4)3 (a = 9.78182(8) Å, S.G. P213, Z = 4) was determined from X-ray powder diffraction data and belongs to the langbeinite-type structures. It is formed by corner-linked V3+O6 octahedra and tetrahedral phosphate groups resulting in a three-dimensional framework. The lead atoms are situated in the structure interstices and only partially occupy their positions. An electron microscopy study confirmed the structure solution. Magnetic susceptibility measurements revealed Curie-Weiss (CW) behavior for Pb1.5V2(PO4)3 at high temperature whereas at around 14 K an abrupt increase on the susceptibility was observed.