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Band engineering in Mg_3Sb_2 by alloying with Mg_3Bi_2 for enhanced thermoelectric performance

Imasato, Kazuki and Kang, Stephen Dongmin and Ohno, Saneyuki and Snyder, G. Jeffrey (2018) Band engineering in Mg_3Sb_2 by alloying with Mg_3Bi_2 for enhanced thermoelectric performance. Materials Horizons, 5 (1). pp. 59-64. ISSN 2051-6347. https://resolver.caltech.edu/CaltechAUTHORS:20171212-104313832

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Abstract

Mg_3Sb_2–Mg_3Bi_2 alloys show excellent thermoelectric properties. The benefit of alloying has been attributed to the reduction in lattice thermal conductivity. However, Mg_3Bi_2-alloying may also be expected to significantly change the electronic structure. By comparatively modeling the transport properties of n- and p-type Mg_3Sb_2–Mg_3Bi_2 and also Mg_3Bi_2-alloyed and non-alloyed samples, we elucidate the origin of the highest zT composition where electronic properties account for about 50% of the improvement. We find that Mg_3Bi_2 alloying increases the weighted mobility while reducing the band gap. The reduced band gap is found not to compromise the thermoelectric performance for a small amount of Mg_3Bi_2 because the peak zT in unalloyed Mg_3Sb_2 is at a temperature higher than the stable range for the material. By quantifying the electronic influence of Mg_3Bi_2 alloying, we model the optimum Mg_3Bi_2 content for thermoelectrics to be in the range of 20–30%, consistent with the most commonly reported composition Mg_3Sb_(1.5)Bi_(0.5).


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1039/c7mh00865aDOIArticle
http://pubs.rsc.org/en/Content/ArticleLanding/2018/MH/C7MH00865APublisherArticle
http://www.rsc.org/suppdata/c7/mh/c7mh00865a/c7mh00865a1.pdfPublisherSupplementary Information
ORCID:
AuthorORCID
Imasato, Kazuki0000-0001-7294-1780
Kang, Stephen Dongmin0000-0002-7491-7933
Ohno, Saneyuki0000-0001-8192-996X
Snyder, G. Jeffrey0000-0003-1414-8682
Alternate Title:Band engineering in Mg3Sb2 by alloying with Mg3Bi2 for enhanced thermoelectric performance
Additional Information:© 2017 The Royal Society of Chemistry. Received 20th October 2017, Accepted 20th November 2017, First published on 20th November 2017. The authors would like to acknowledge support from the U.S. Department of Energy, Office of Science, Basic Energy Sciences through the Solid-State Solar-Thermal Energy Conversion Center (S3TEC), an Energy Frontier Research Center (DE-SC0001299), and also from the NASA Science Mission Directorate's Radioisotope Power Systems Thermoelectric Technology Development program. KI acknowledges support from Funai Foundation for Information Technology. There are no conflicts to declare.
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0001299
NASAUNSPECIFIED
Funai Foundation for Information TechnologyUNSPECIFIED
Issue or Number:1
Record Number:CaltechAUTHORS:20171212-104313832
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20171212-104313832
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:83825
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:12 Dec 2017 19:10
Last Modified:03 Oct 2019 19:11

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