Bux, Sabah K. and Zevalkink, Alexandra and Janka, Oliver and Uhl, David and Kauzlarich, Susan and Snyder, Jeffrey G. and Fleurial, Jean-Pierre (2014) Glass-like lattice thermal conductivity and high thermoelectric efficiency in Yb_9Mn_(4.2)Sb_9. Journal of Materials Chemistry A, 2 (1). pp. 215-220. ISSN 2050-7488. http://resolver.caltech.edu/CaltechAUTHORS:20140113-112906365
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Abstract
Motivated by excellent thermoelectric performance in the well-known Yb-based Zintl compounds Yb_(14)MnSb_(11) and YbZn_(2−x)Mn_xSb_2, this study investigates the thermoelectric properties of Yb_9Mn_(4.2)Sb_9. Unlike most transition metal containing Zintl phases, Yb_9Mn_(4.2)Sb)9 contains a partially occupied Mn site and thus does not have a valence-precise stoichiometry. Samples were synthesized by direct ball milling of the elements, followed by hot pressing. Consistent with previous reports, X-ray diffraction and wavelength dispersive spectroscopy confirmed a narrow composition range near Yb_9Mn_(4.2)Sb_9. High temperature measurements of the electronic properties of Yb_9Mn_(4.2)Sb_9 indicate that it is a degenerate p-type semiconductor with a band gap sufficiently large for high temperature thermoelectric applications. Hall measurements reveal that Yb_9Mn_(4.2)Sb_9 has a high extrinsic carrier concentration (~10^(20) h^+ cm^(−3)), which is due to the deviation from the theoretical “Zintl composition” of Yb_9Mn_(4.5)Sb_9. The measured carrier concentration coincides with the optimum concentration predicted using a single parabolic band model. Measurements of the thermal diffusivity and heat capacity reveal an extremely low, temperature-independent lattice thermal conductivity in this compound (κ_L < 0.4 W mK^(−1)), which is due to both the large unit cell size (44 atoms per primitive cell) and substantial disorder on the Mn site. This favorable combination of optimized electronic properties and low lattice thermal conductivity leads to a promising figure of merit at high temperature (zT = 0.7 at 950 K).
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| Additional Information: | © 2014 The Royal Society of Chemistry. Received 7th October 2013. Accepted 11th October 2013. The authors would like to thank Dr Thierry Caillat for his helpful discussions. They would also like to thank Leslie D. Zoltan, George Nakatsukasa and Dr Pawan Gogna for their assistance in sample characterization and measurement. This work was performed at the Jet Propulsion Laboratory, California Institute of Technology under contract with the National Aeronautics and Space Administration. This work was supported by the NASA Science Missions Directorate’s Radioisotope Power Systems Technology Advancement Program. | |||||||||
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| Record Number: | CaltechAUTHORS:20140113-112906365 | |||||||||
| Persistent URL: | http://resolver.caltech.edu/CaltechAUTHORS:20140113-112906365 | |||||||||
| Official Citation: | Glass-like lattice thermal conductivity and high thermoelectric efficiency in Yb9Mn4.2Sb9 Sabah K. Bux, Alexandra Zevalkink, Oliver Janka, David Uhl, Susan Kauzlarich, Jeffrey G. Snyder and Jean-Pierre Fleurial J. Mater. Chem. A, 2014, 2, 215-220 | |||||||||
| Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | |||||||||
| ID Code: | 43342 | |||||||||
| Collection: | CaltechAUTHORS | |||||||||
| Deposited By: | Ruth Sustaita | |||||||||
| Deposited On: | 13 Jan 2014 21:25 | |||||||||
| Last Modified: | 18 Nov 2016 17:28 |
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