The Crystal Structures of the Binary Mixed Valence Compound Bi(III)3Bi(V)O7 and Isotypic Bi3SbO7 as Determined by High Resolution X-Ray and Neutron Powder Diffraction
✍ Scribed by Robert E. Dinnebier; Richard M. Ibberson; Helmut Ehrenberg; Martin Jansen
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 546 KB
- Volume
- 163
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
The crystal structures of the mixed valence compound Bi (IIII) 3 Bi (V) O 7 (1) and isotypic Bi (III) 3 Sb (V) O 7 (2) were determined ab initio from powder di4raction data. At room temperature, both structures crystallize in space group P1 (Z ؍ 2) with a ؍ 6.7253( 2), b ؍ 6.9950(2), c ؍ 7.7961(2) A > , ؍ 72.566(2), ؍ 88.842(2), ؍ 76.925(2)3, and V ؍ 340.39(2) A > 3 for (1) and a ؍ 6.6044(3), b ؍ 7.0146(3), c ؍ 7.6048(3) A > , ؍ 73.388(2), ؍ 89.225(2), ؍ 76.190(2)3, and V ؍ 327.28(2) A > 3 for (2). Combined Rietveld re5nements based on both synchrotron and neutron powder patterns were performed (T ؍ 295 K, R-Bragg ؍ 5.4% for (1), R-Bragg ؍ 6.4% for (2)). The crystal structures contain 5ve crystallographically di4erent anion polyhedra in two di4erent coordination types and can be related to the CaF 2 -type structure with the cations forming a distorted face centered cubic lattice and the oxygen atoms 5lling positions close to seven of the eight tetrahedral cavities.