Structure of a new CaII1/3SbV1/6BiIII1/2PO4 phosphate

Abstract

A new Ca1/3Sb1/6Bi1/2PO4 “CaSb0.50Bi1.50(PO4)3” phosphate has been synthesized by conventional solid-state reaction techniques at 900 °C in air atmosphere. Their crystallographic structures were determined at room temperature from X-ray powder diffraction (XRPD) data using the Rietveld analysis. CaII1/3SbV1/6BiIII1/2PO4 material possesses the high-temperature BiPO4 monoclinic structure variety. It crystallizes in monoclinic system with P21/m space group and the cell parameters are: a = 4.9358(1) Å, b = 6.9953(2), c = 4.7075(1) Å, and β = 96.2(1)°. Their structure can be described as composed of alternating edge-sharing AO8 (A = Ca, Sb, Bi) bisdisphenoids and PO4 tetrahedra forming chains parallel to the b axis. Every AO8 polyhedron is surrounded by six PO4 and every PO4 tetrahedron is surrounded by six AO8 polyhedra. Infrared spectroscopic study was used to obtain further structural information.