Pressure-dependence of the phase transitions and thermal expansion in zirconium and hafnium pyrovanadate
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332‐0400 (United States)
Low or negative thermal expansion (NTE) has been previously observed in members of the ZrP{sub 2}O{sub 7} family at temperatures higher than their order-disorder phase transitions. The thermoelastic properties and phase behavior of the low temperature superstructure and high temperature negative thermal expansion phases of ZrV{sub 2}O{sub 7} and HfV{sub 2}O{sub 7} were explored via in situ variable temperature/pressure powder x-ray diffraction measurements. The phase transition temperatures of ZrV{sub 2}O{sub 7} and HfV{sub 2}O{sub 7} exhibited a very strong dependence on pressure (∼700 K GPa), with moderate compression suppressing the formation of their NTE phases below 513 K. Compression also reduced the magnitude of the coefficients of thermal expansion in both the positive and negative thermal expansion phases. Additionally, the high temperature NTE phase of ZrV{sub 2}O{sub 7} was found to be twice as stiff as the low temperature positive thermal expansion superstructure (24 and 12 GPa respectively). - Graphical abstract: The temperature at which ZrV{sub 2}O{sub 7} transforms to a phase displaying negative thermal expansion is strongly pressure dependent. The high temperature form of ZrV{sub 2}O{sub 7} is elastically stiffer than the low temperature form. - Highlights: • The order-disorder phase transition temperatures in ZrV{sub 2}O{sub 7} and HfV{sub 2}O{sub 7} are strongly pressure dependent (∼700 K.GPa). • The high temperature (disordered) phase of ZrV{sub 2}O{sub 7} is much stiffer than the ambient temperature (ordered) phase. • Compression reduces the magnitude of the negative thermal expansion in the high temperature phase of ZrV{sub 2}O{sub 7}.
- OSTI ID:
- 22658259
- Journal Information:
- Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Vol. 249; ISSN 0022-4596; ISSN JSSCBI
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
AMBIENT TEMPERATURE
COMPRESSION
HAFNIUM COMPOUNDS
ORDER-DISORDER TRANSFORMATIONS
PHOSPHATES
PRESSURE DEPENDENCE
PRESSURE RANGE GIGA PA
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0400-1000 K
THERMAL EXPANSION
TRANSITION TEMPERATURE
VANADATES
X-RAY DIFFRACTION
ZIRCONIUM COMPOUNDS