Composition and temperature dependent phase transitions in Co–W double perovskites, a synchrotron X-ray and neutron powder diffraction study

• Published in: Journal of solid state chemistry 2007-02, Vol.180 (2), p.541-548
• Main Authors: Zhou, Qingdi, Kennedy, Brendan J., Elcombe, Margaret M.
• Format: Article
• Language: English
• Subjects: BARIUM COMPOUNDS; CALCIUM COMPOUNDS; CATIONS; COBALT COMPOUNDS; Condensed matter: structure, mechanical and thermal properties; Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder; Cross-disciplinary physics: materials science; rheology; Crystalline state (including molecular motions in solids); CUBIC LATTICES; Double perovskites; Exact sciences and technology; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; Materials science; MIXTURES; MONOCLINIC LATTICES; NEUTRON DIFFRACTION; OXIDES; PEROVSKITE; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; PHASE TRANSFORMATIONS; Physics; Single-crystal and powder diffraction; STRONTIUM COMPOUNDS; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; SYMMETRY; Synchrotron and neutron diffraction; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0273-0400 K; TETRAGONAL LATTICES; Theory of crystal structure, crystal symmetry; calculations and modeling; TUNGSTEN COMPOUNDS; X RADIATION; X-ray diffraction and scattering
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2006.10.038

High-resolution synchrotron and neutron powder diffraction techniques were used to determine precise structures for the series of perovskite oxides A 2− x Sr x CoWO 6 ( A Ca, or Ba, 0⩽ x⩽2). The studies demonstrated that the symmetry decreases as the average size of the A-site cation decreases with a sequential introduction of in-phase and out-of-phase tilting of the BO 6 octahedra. A cubic structure in Fm3¯ m with rock-salt like ordering of the Co and W cations was formed for Ba 2− x Sr x CoWO 6 with x∼