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Improving Thermoelectric Performance of α‐MgAgSb by Theoretical Band Engineering Design
Author(s) -
Tan Xiaojian,
Wang Ling,
Shao Hezhu,
Yue Song,
Xu Jingtao,
Liu Guoqiang,
Jiang Haochuan,
Jiang Jun
Publication year - 2017
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201700076
Subject(s) - materials science , thermoelectric effect , bismuth telluride , thermoelectric materials , engineering physics , energy conversion efficiency , condensed matter physics , electronic band structure , doping , dopant , seebeck coefficient , thermoelectric generator , power factor , optoelectronics , thermodynamics , power (physics) , physics
α‐MgAgSb is recently discovered to be a new class of thermoelectric material near room temperature. A competitive ZT of 1.4 at 525 K is achieved in Ni‐doped α‐MgAgSb, and the measured efficiency of energy conversion reaches a record value of 8.5%, which is even higher than that of the commercially applied material bismuth telluride. On the other hand, the band structure of α‐MgAgSb is believed to be unprofitable to the power factor, owing to the less degenerate valence valleys. Here, this paper reports a systematic theoretical study on the thermoelectric properties by using the electron/phonon structure and transport calculations. Based on the careful analysis of Fermi surface, a principled scheme is presented to design band engineering in α‐MgAgSb. Following the given rules, several effective dopants are predicted. As two examples, Zn‐ and Pd‐doped α‐MgAgSb are numerically confirmed to exhibit an extraordinary ZT value of 2.0 at 575 K and a high conversion efficiency of 12.6%, owing to the effects of band convergence. This work develops an applicable scheme for the purposive design of band engineering, and the idea can be simply applied to more thermoelectric materials.