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Author Gallington, Leighanne C. ♦ Hester, Brett R. ♦ Kaplan, Benjamin S. ♦ Wilkinson, Angus P.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY ♦ INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY ♦ 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
Abstract 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}.
ISSN 00224596
Educational Use Research
Learning Resource Type Article
Publisher Date 2017-05-15
Publisher Place United States
Journal Journal of Solid State Chemistry
Volume Number 249


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