Journal
JOURNAL OF COMPUTATIONAL CHEMISTRY
Volume 40, Issue 18, Pages 1693-1700Publisher
WILEY
DOI: 10.1002/jcc.25822
Keywords
band-resolved COHP; Mg3Sb2; band engineering; thermoelectric; bonding ionicity
Categories
Funding
- National Key Research and Development Program of China [2017YFB0701600]
- Natural Science Foundation of China [11674211, 51632005]
- 111 project [D16002]
- program of Shanghai Subject Chief Scientist [16XD1401100]
- Guangdong Innovation Research Team Project [2017ZT07C062]
- Shenzhen Pengcheng-Scholarship program
- U.S. Department of Energy. Office of Science, Basic Energy Sciences [DE-SC0019114]
- NASA Jet Propulsion Laboratory
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Identifying strategies for beneficial band engineering is crucial for the optimization of thermoelectric (TE) materials. In this study, we demonstrate the beneficial effects of ionic dopants on n-type Mg3Sb2. Using the band-resolved projected crystal orbital Hamilton population, the covalent characters of the bonding between Mg atoms at different sites are observed. By partially substituting the Mg at the octahedral sites with more ionic dopants, such as Ca and Yb, the conduction band minimum (CBM) of Mg3Sb2 is altered to be more anisotropic with an enhanced band degeneracy of 7. The CBM density of states of doped Mg3Sb2 with these dopants is significantly enlarged by band engineering. The improved Seebeck coefficients and power factors, together with the reduced lattice thermal conductivities, imply that the partial introduction of more ionic dopants in Mg3Sb2 is a general solution for its n-type TE performance. (c) 2019 Wiley Periodicals, Inc.
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