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Band engineering in Mg3Sb2 by alloying with Mg3Bi2 for enhanced thermoelectric performance†
Materials Horizons ( IF 12.2 ) Pub Date : 2017-11-20 00:00:00 , DOI: 10.1039/c7mh00865a
Kazuki Imasato 1, 2, 3, 4 , Stephen Dongmin Kang 1, 2, 3, 4, 5 , Saneyuki Ohno 1, 2, 3, 4, 5 , G. Jeffrey Snyder 1, 2, 3, 4
Affiliation  

Mg3Sb2–Mg3Bi2 alloys show excellent thermoelectric properties. The benefit of alloying has been attributed to the reduction in lattice thermal conductivity. However, Mg3Bi2-alloying may also be expected to significantly change the electronic structure. By comparatively modeling the transport properties of n- and p-type Mg3Sb2–Mg3Bi2 and also Mg3Bi2-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 Mg3Bi2 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 Mg3Bi2 because the peak zT in unalloyed Mg3Sb2 is at a temperature higher than the stable range for the material. By quantifying the electronic influence of Mg3Bi2 alloying, we model the optimum Mg3Bi2 content for thermoelectrics to be in the range of 20–30%, consistent with the most commonly reported composition Mg3Sb1.5Bi0.5.

中文翻译:

通过与Mg 3 Bi 2合金化 在Mg 3 Sb 2中进行能带工程以增强热电性能

Mg 3 Sb 2 –Mg 3 Bi 2合金具有出色的热电性能。合金化的好处归因于晶格热导率的降低。然而,还可以预期,Mg 3 Bi 2合金化将显着改变电子结构。通过对n型和p型Mg 3 Sb 2 –Mg 3 Bi 2以及Mg 3 Bi 2合金和非合金样品的传输特性进行比较建模,我们阐明了最高zT的起源电子性能约占改进量的50%。我们发现,Mg 3 Bi 2合金化增加了加权迁移率,同时减小了带隙。发现减少的带隙对于少量的Mg 3 Bi 2不会损害热电性能,因为合金化的Mg 3 Sb 2中的峰值zT处于高于材料稳定范围的温度下。通过量化Mg 3 Bi 2合金化的电子影响,我们对最佳Mg 3 Bi 2进行建模热电材料的含量应在20%至30%的范围内,与最常报告的成分Mg 3 Sb 1.5 Bi 0.5一致
更新日期:2017-11-20
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