Pb{sub 2}BiO{sub 2}PO{sub 4}, a new oxyphosphate
- ENSCL, Villeneuve d`Ascq (France)
- Univ. of Texas, Austin, TX (United States)
Pb{sub 2}BiO{sub 2}PO{sub 4} is orthorhombic with space group PnMa, a = 5.930(4), b = 9.079(10), c = 11.473 (6) {angstrom} at room temperature, Z = 4, and a congruent melting point of 860{degrees}C. The structure was solved from single crystal and powder diffraction data. The PO{sub 4} ion 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 BiO{sub 2} rectangular pyramids formed by edge-sharing parallel to the a axis 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 6s{sup 2} lone pair extends toward that apex. Pb is bonded to six oxygen atoms forming a distorted octahedron when distances less than 3 {angstrom} are considered. When two additional oxygen ions at 3.20(9) and 3.24(5){angstrom} are considered part of the coordination polyhedron it can be described as a bisdisphenoid. This structure is related to structures found in many M{sub 2}{sup II}BiXO{sub 6} phases. The Raman spectrum shows the expected frequencies for PO{sub 4}. 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{sup -1} are attributed to internal vibrational modes of the BiO{sub 4} pyramid.
- OSTI ID:
- 613715
- Journal Information:
- Journal of Solid State Chemistry, Vol. 133, Issue 2; Other Information: PBD: 1 Nov 1997
- Country of Publication:
- United States
- Language:
- English
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