Low thermal conductivity of the negative thermal expansion material, HfMo2O8
Date
2007-04
Authors
Kennedy, Catherine A.
White, Mary Anne
Wilkinson, Angus P.
Varga, Tamas
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Abstract
The thermal conductivity of the cubic polymorph of hafnium molybdate, HfMo2O8, was determined
over the temperature range of 2-400 K. The values of thermal conductivity were low (0.64 +/- 0.15 W
m(-1) K-1 at T=300 K for a fully dense sample), with a positive temperature coefficient throughout
the temperature range examined. Calculations of the theoretical minimum thermal conductivity and the
effective phonon mean free path show that the heat-carrying phonons are nearly fully coupled in
HfMo2O8, consistent with the rather large magnitude of its Gruneisen parameter. The low-frequency
optic modes which lead to negative thermal expansion in HfMo2O8 are likely responsible for the low
thermal conductivity. (c) 2007 American Institute of Physics.
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Citation
Kennedy, Catherine A., Mary Anne White, Angus P. Wilkinson, and Tamas Varga. 2007. "Low thermal conductivity of the negative thermal expansion material, HfMo2O8." Applied Physics Letters 90(15): 151906-151906.