The high-temperature phases of WO{sub 3}

Journal Article · Thu Apr 01 04:00:00 EST 1999 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1006/jssc.1999.8173· OSTI ID:349934

Vogt, T ^[1]; Woodward, P M ^[2]; Hunter, B A ^[3]

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1. Brookhaven National Lab., Upton, NY (United States). Physics Dept.
2. Ohio State Univ., Columbus, OH (United States)
3. 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 Laboratory (BNL), Upton, NY
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 349934
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 144; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
EXPERIMENTAL DATA
LATTICE PARAMETERS
NEUTRON DIFFRACTION
PHASE STUDIES
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
TUNGSTEN OXIDES