Abstract

Pb2BiO2PO4is orthorhombic with space groupPnma,a=5.930(4),b=9.079(10),c=11.473 (6) Å at room temperature,Z=4, and a congruent melting point of 860°C. The structure was solved from single crystal and powder diffraction data. The PO4ion can occupy two energetically equivalent positions causing two oxygen atoms to be disordered. The structure can be described on the basis of several motifs. Infinite chains of BiO2rectangular pyramids formed by edge-sharing parallel to theaaxis that are linked by lead atoms and phosphate anions. Bi can also be considered as present in a trigonal prismatic environment of oxygen atoms in which one corner of a triangular face is unoccupied. Presumably the 6s2lone pair extends toward that apex. Pb is bonded to six oxygen atoms forming a distorted octahedron when distances less than 3 Å are considered. When two additional oxygen ions at 3.20(9) and 3.24(5) Å are considered part of the coordination polyhedron it can be described as a bisdisphenoid. This structure is related to structures found in manyMII2BiXO6phases. The Raman spectrum shows the expected frequencies for PO4. In addition frequencies are observed that can be assigned to P–O–Bi and P–O–Pb linkages. Intense bands at 143 and 150 cm−1are attributed to internal vibrational modes of the BiO4pyramid.

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