Mg Alloying in SnTe Facilitates Valence Band Convergence and Optimizes Thermoelectric Properties
Mg Alloying in SnTe Facilitates Valence Band Convergence and Optimizes Thermoelectric Properties
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DOI：
10.1021/cm504112m
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发表时间：
2015-01-27
影响因子：
8.6
通讯作者：
Biswas, Kanishka
中科院分区：
文献类型：
--
作者：
Banik, Ananya;Shenoy, U. Sandhya;Biswas, Kanishka
SnTe是PbTe的一种无铅岩盐类似物，具有与PbTe相似的价带结构，近年来在热电热发电方面引起了人们的关注。然而，纯SnTe是一种较差的热电材料，因为本征锡空位导致非常高的空穴浓度，导致低塞贝克系数和高电导率。在这份报告中，我们表明，SnTe可以优化成为一个高性能的热电发电材料，通过控制空穴浓度和显着提高塞贝克系数。Mg（2- 10mol%）合金化可通过增加SnTe的带隙来调节SnTe的电子能带结构，并导致其轻重空穴价带之间的能量分离减小。因此，固溶合金化与Mg增强的贡献的重空穴价带，导致显着改善的塞贝克系数在镁合金化的SnTe，这反过来又导致显着提高功率因数。最大热电优值，ZT，类似于1.2，在860 K的高品质的结晶锭的p型Sn 0.94 Mg 0.09 Te。
SnTe, a lead-free rock-salt analogue of PbTe, having valence band structure similar to PbTe, recently has attracted attention for thermoelectric heat to electricity generation. However, pristine SnTe is a poor thermoelectric material because of very high hole concentration resulting from intrinsic Sn vacancies, which give rise to low Seebeck coefficient and high electrical thermal conductivity. In this report, we show that SnTe can be optimized to be a high performance thermoelectric material for power generation by controlling the hole concentration and significantly improving the Seebeck coefficient. Mg (2-10 mol %) alloying in SnTe modulates its electronic band structure by increasing the band gap of SnTe and results in decrease in the energy separation between its light and heavy hole valence bands. Thus, solid solution alloying with Mg enhances the contribution of the heavy hole valence band, leading to significant improvement in the Seebeck coefficient in Mg alloyed SnTe, which in turn results in remarkable enhancement in power factor. Maximum thermoelectric figure of merit, ZT, of similar to 1.2 is achieved at 860 K in the high quality crystalline ingot of p-type Sn0.94Mg0.09Te.