Crystal structures of the ionic conductors Bi{sub 46}M{sub 8}O{sub 89} (M=P, V) related to the fluorite-type structure
- Institut de Chimie de la Matiere Condensee de Bordeaux (ICMCB), UPR9048 CNRS, Universite de Bordeaux 1, 87 Avenue du Docteur Albert Schweitzer, Pessac Cedex FR-33608 (France)
- Facultad de Ciencias, Departamento de Fisica de la Materia Condensada, Universidad del Pais Vasco, Apdo 644, Bilbao 48080 (Spain)
The crystal structures of the two oxides Bi{sub 46}M{sub 8}O{sub 89} (M=P, V) have been solved from single crystals X-ray data at room temperature. Bi{sub 46}P{sub 8}O{sub 89} crystallizes in the monoclinic symmetry (space group C2/m) with the cell parameters a=19.6073(4)A, b=11.4181(4)A, c=21.1119(4)A and {beta}=112.14(3){sup o}. The symmetry of Bi{sub 46}V{sub 8}O{sub 89} is also monoclinic but the space group is P2{sub 1}/c with the unit-cell parameters: a=20.0100(4)A, b=11.6445(4)A, c=20.4136(4)A and {beta}=107.27(3){sup o}. Both structures derive from an oxygen deficient fluorite-type structure where the Bi and M cations (M=P, V) are ordered in the framework. The structures are characterised by isolated MO{sub 4} tetrahedra (M=P, V) which contradicts the previous results. The difference between the two structures is only due to a different order of the M atoms (M=P, V) in the fluorite-type superstructure. It will be shown that some oxygen sites are partially occupied in both structures which can explain the ion conduction properties of these phases. A structural building principle will be proposed that can explain the large domain of solid solution related to the fluorite-type observed in both systems.
- OSTI ID:
- 20725959
- Journal Information:
- Journal of Solid State Chemistry, Vol. 178, Issue 6; Other Information: DOI: 10.1016/j.jssc.2005.03.013; PII: S0022-4596(05)00103-9; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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