Exceptional thermoelectric performance in Mg_3Sb_(0.6)Bi_(1.4) for low-grade waste heat recovery
Abstract
Bi_2Te_3 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 Mg_3Sb_(0.6)Bi_(1.4), with a thermoelectric figure-of-merit zT of 1.0–1.2 at 400–500 K, finally surpasses n-type Bi_2Te_3. This exceptional performance is achieved by tuning the alloy composition of Mg_3(Sb_(1−x)Bi_x)_2. The two primary mechanisms of the improvement are the band effective-mass reduction and grain size enhancement as the Mg_3Bi_2 content increases. The benefit of the effective-mass reduction is only effective up to the optimum composition Mg_3Sb_(0.6)Bi_(1.4), 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 Mg_3Sb_(0.6)Bi_(1.4) is a significant advancement towards sustainable heat recovery technology.
Additional Information
© 2019 The Royal Society of Chemistry. The article was received on 16 Nov 2018, accepted on 14 Feb 2019 and first published on 14 Feb 2019. The authors would like to acknowledge support from the NASA Science Mission Directorate's Radioisotope Power Systems Thermoelectric Technology Development program. KI acknowledges support from the Funai Foundation for Information Technology. The EBSD in this work made use of the EPIC facility of Northwestern University's NUANCE Center, which has received support from: the Soft and Hybrid Nanotechnology Experimental Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1720139) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; the State of Illinois, through the IIN. Author contributions: KI synthesized and measured the samples. KI and SDK analyzed the data. SDK and KI wrote the manuscript. SDK supervised the project with the advice from GJS. All authors reviewed or edited the manuscript. The authors declare no competing interests.Attached Files
Supplemental Material - c8ee03374a1_si.pdf
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Additional details
- Alternative title
- Exceptional thermoelectric performance in Mg3Sb0.6Bi1.4 for low-grade waste heat recovery
- Eprint ID
- 93243
- DOI
- 10.1039/c8ee03374a
- Resolver ID
- CaltechAUTHORS:20190226-082629002
- NASA
- Funai Foundation for Information Technology
- NSF
- ECCS-1542205
- NSF
- DMR-1720139
- International Institute for Nanotechnology (IIN)
- W. M. Keck Foundation
- State of Illinois
- Created
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2019-02-26Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field