The Upper Limit of the Solid Solution Bi2−x SbxMoO6: Structure Refinement of Bi1.1Sb0.9MoO6

✍ Scribed by P. Bégué; R. Enjalbert; A. Castro

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 684 KB
• Volume: 159
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2001.9133

✦ Synopsis

The crystal structure of Bi 1.1 Sb 0.9 MoO 6 has been re5ned using X-ray and neutron powder di4raction combined with Rietveld analysis. This oxide is isostructural with the high-temperature form of Bi 2 MoO 6 ( (H)) belonging to the monoclinic system, space group P2 1 /c, a ‫؍‬ 17.0988(7) A s , b ‫؍‬ 22.3342(9) A s , c ‫؍‬ 5.5679(2) A s , ‫؍‬ 90.926(3)3, V ‫؍‬ 2126.0(1) A s 3 , Z ‫؍‬ 16, and cal ‫؍‬ 6.64 g.cm ؊ 3 . The phase stoichiometry has been veri5ed and constitutes the upper limit of the Bi 2 ؊ x Sb x MoO 6 solid solution. Antimony atoms progressively go to bismuth sites in an ordered way that can be understood according to Bi/Sb+O observed distances and the stereoactivity of 5s 2 and 6s 2 lone pair of electrons of Sb 3 ؉ and Bi 3 ؉ , respectively. The maximum x ‫؍‬ 0.9 substitution value for this solid solution is explained on the basis of the bond-valence method. The Bi/Sb+O bond valence generally decreases with increasing antimony content, reaching strongly underbonded Bi/Sb+O states beyond which the substitution cannot progress.