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Issue 3, 2019
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Exceptional thermoelectric performance in Mg3Sb0.6Bi1.4 for low-grade waste heat recovery

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Abstract

Bi2Te3 alloys have been the most widely used n-type material for low temperature thermoelectric power generation for over 50 years, thanks to the highest efficiency in the 300–500 K temperature range relevant for low-grade waste-heat recovery. Here we show that n-type Mg3Sb0.6Bi1.4, with a thermoelectric figure-of-merit zT of 1.0–1.2 at 400–500 K, finally surpasses n-type Bi2Te3. This exceptional performance is achieved by tuning the alloy composition of Mg3(Sb1−xBix)2. The two primary mechanisms of the improvement are the band effective-mass reduction and grain size enhancement as the Mg3Bi2 content increases. The benefit of the effective-mass reduction is only effective up to the optimum composition Mg3Sb0.6Bi1.4, after which a different band dominates charge transport. The larger grains are important for minimizing grain-boundary electrical resistance. Considering the limited choice for low temperature n-type thermoelectric materials, the development of Mg3Sb0.6Bi1.4 is a significant advancement towards sustainable heat recovery technology.

Graphical abstract: Exceptional thermoelectric performance in Mg3Sb0.6Bi1.4 for low-grade waste heat recovery

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Supplementary files

Article information


Submitted
16 Nov 2018
Accepted
14 Feb 2019
First published
14 Feb 2019

Energy Environ. Sci., 2019,12, 965-971
Article type
Communication
Author version available

Exceptional thermoelectric performance in Mg3Sb0.6Bi1.4 for low-grade waste heat recovery

K. Imasato, S. D. Kang and G. J. Snyder, Energy Environ. Sci., 2019, 12, 965
DOI: 10.1039/C8EE03374A

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