Abstract
Skutterudites, such as CoSb3, are a promising class of thermoelectric materials, particularly when the voids in the crystal structure are filled with guest atoms. We report a comprehensive study of the effects of filling skutterudites with misch-metal (Mm), a rare-earth alloy having the naturally occurring La, Ce, Pr, and Nd composition. Our power diffraction experiments show that Mm filling causes a larger expansion and an unusual distortion of the CoSb3 lattice compared with single-element-filled skutterudites. We probed the response of crystal lattice, electronic structure, and carrier and phonon scattering mechanisms to Mm filling using neutron powder diffraction, Hall effect, electrical resistivity, thermopower, and thermal conductivity measurements between 2 and 300 K on a series of Mmy Fe4-x Cox Sb12 samples. The thermoelectric properties of these Mm-filled skutterudites in this low temperature range are comparable to those of pure Ce-filled skutterudites despite the anomalous lattice expansion and distortion. We expect that these materials will have high thermoelectric figures of merit at elevated temperatures.
Original language | English |
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Article number | 083702 |
Journal | Journal of Applied Physics |
Volume | 102 |
Issue number | 8 |
DOIs | |
State | Published - 2007 |
Funding
J.Y. and G.P.M. want to thank Dr. Jan F. Herbst and Dr. Mark W. Verbrugge for continuous support and encouragement. The authors would like to thank R. A. Waldo and M. P. Balogh for assistance in EPMA and x-ray diffraction measurements. The work is in part supported by GM, by DOE under corporate agreement DE-FC26-04NT42278, by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Transportation Technologies as part of the High Temperature Materials Laboratory User Program, and by the Waste Heat Recovery Program via the corporate agreement DE-FC26-04NT42278 at Oak Ridge National Laboratory managed by the UT-Battelle LLC, for the Department of Energy under contract DE-AC05000OR22725. Certain trade names and company products are identified in order to specify experimental procedures adequately. In no case does such identification imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the products are necessarily the best available for the purpose.