Crystal structure of WPO 5, the second member of the monophosphate tungsten bronze series (WO 3) 2 m(PO 2) 4

Abstract

Sealed tube reactions of WO 3, P 2O 5, and W metal at 1250°C give crystals of WPO 5. The compound was characterized by single-crystal X-ray diffraction data with a = 11.174(3), b = 6.550(2), c = 5.228(1) Å, Z = 4, in the space group Pna2 1. The structure was refined to R( F) = 0.0273 and R w = 0.0268 for 547 independent reflections with I > 3.0 σ( I). This compound, which contains only W 5+, is composed of corner-sharing WO 6 octahedra and PO 4 tetrahedra. Pentagonal tunnels along the c-axis are formed by the edges of three octahedra and two tetrahedra. The framework can also be described as built up from ReO 3-type slabs which are connected through phosphate groups. It corresponds to the second member ( m = 2) of the monophosphate tungsten bronze series (WO 3) 2 m (PO 2) 4.