The high-temperature phases of WO{sub 3}
- Brookhaven National Lab., Upton, NY (United States). Physics Dept.
- Ohio State Univ., Columbus, OH (United States)
- Australian Nuclear Science and Technology Organisation, Menai, New South Wales (Australia)
High-temperature, high-resolution neutron powder diffraction experiments were performed to investigate the phases of WO{sub 3} between room temperature and 850 C. Two phases were found and characterized by Rietveld refinements: orthorhombic {beta}-WO{sub 3} (Pbcn, a = 7.3331(2), b = 7.5733(2), c = 7.7401(3) {angstrom} at 350 C, tilt system a{sup 0}b{sup +}c{sup {minus}}) and tetragonal {alpha}-WO{sub 3} (P4/ncc, a = 5.27659(1), b = 5.2759(1), c = 7.8462(3) {angstrom} at 800 C, tilt system a{sup 0}a{sup 0}c{sup {minus}}). The sequence of temperature-induced phase transitions in WO{sub 3} can be rationalized in terms of changes in the octahedral tilt systems and/or displacements of the tungsten out of the center of the WO{sub 6} octahedron. Above room temperature the two phase transitions are driven by successive softening of phonon modes, M{sub 3} at the {alpha}- to {beta}-transition and R{sub 25} at the {beta}- to {gamma}-transition.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC02-98CH10886
- OSTI ID:
- 349934
- Journal Information:
- Journal of Solid State Chemistry, Vol. 144, Issue 1; Other Information: PBD: Apr 1999
- Country of Publication:
- United States
- Language:
- English
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