Thermal expansion in the orthorhombic {gamma} phase of ZrW{sub 2}O{sub 8}
- Department of Chemistry, University Science Laboratories, University of Durham, South Road, Durham, DH1 3LE, (United Kingdom)
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
- ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX, (United Kingdom)
- Department of Chemistry and Center for Advance Materials Research, Oregon State University, Corvallis, Oregon 97331 (United States)
The thermal expansion of the orthorhombic {gamma} phase of ZrW{sub 2}O{sub 8} has been measured using neutron powder diffraction from 4.6 to 410 K, where it transforms to the cubic {alpha} phase. At low temperature, {gamma}-ZrW{sub 2}O{sub 8} has a negative thermal expansion, but the thermal expansion becomes less negative with increasing temperature and is slightly positive at room temperature. This behavior can be explained in terms of the contributing phonon modes: At low temperature, the vibrational modes lead to a negative thermal expansion, but additional modes that become active upon increasing temperature add positive contributions. Above room temperature, the a and b axes increase more sharply while the c axis reverses its behavior and decreases with increasing temperature. This unusual behavior can be explained in terms of a thermally activated process, presumed to result from oxygen-atom migration, that makes an additional contribution to the thermal expansion. (c) 1999 The American Physical Society.
- OSTI ID:
- 20217941
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 60, Issue 21; Other Information: PBD: 1 Dec 1999; ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
THERMAL EXPANSION
ORTHORHOMBIC LATTICES
ZIRCONIUM OXIDES
TUNGSTEN OXIDES
NEUTRON DIFFRACTION
POWDER METALLURGY
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0000-0013 K
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
VIBRATIONAL STATES
EXPERIMENTAL DATA