Enhanced thermoelectric performance of n-type transformable AgBiSe2 polymorphs by indium doping
Enhanced thermoelectric performance of n-type transformable AgBiSe2 polymorphs by indium doping
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铟掺杂增强 n 型可转变 AgBiSe2 多晶型物的热电性能
DOI：
10.1063/1.4963779
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发表时间：
2016-09-26
影响因子：
4
通讯作者：
Liang, Xin
中科院分区：
文献类型：
--
作者：
Liu, Xiaocun;Jin, Dou;Liang, Xin
我们证明了通过在银位上掺杂铟来改善 n 型无铅可转变 AgBiSe2 多晶型物的热电性能。 X 射线衍射分析表明，在 [In] = 0.02 范围内，完整的固溶体形成良好。正如我们的密度泛函理论 (DFT) 计算所表明的那样，由于局部铟杂质水平调整的载流子浓度的主导作用，电导率和塞贝克系数的表现通常相反。随着铟浓度的增加，我们观察到在 450 至 580 K 范围内热电输运特性随温度发生剧烈变化。通过进行等温电测量，我们将这种有趣的行为归因于正在进行的 α 到 β 相变过程。正如我们的 DFT 计算所示，5s 内的孤对电子增加了化学键的非谐性并增强了声子-声子散射。这与引入的 InAg.. 点缺陷一起，进一步降低了晶格热导率。最大热电品质因数 ZT 在 773 K 时实现，并从原始 AgBiSe2 的 0.3 增加到最佳 [In] = 0.015 掺杂的 0.7，增强了两倍以上。
We demonstrate the improved thermoelectric properties of n-type lead-free transformable AgBiSe2 polymorphs by indium doping on silver sites. X-ray diffraction analysis suggests that complete solid solutions are well formed up to [In] = 0.02. Electrical conductivity and Seebeck coefficient behave in a routinely opposite manner due to the dominant role of the carrier concentration adjusted by the localized indium impurity levels, as also suggested by our density functional theory (DFT) calculations. As indium concentration increases, we observe a drastic variation of the thermoelectric transport properties with temperature, in the range of 450 to 580 K. By performing the isothermal electrical measurements, we attribute this interesting behavior to the ongoing α to β phase transformation process. The In 5s lone pair electrons, as indicated from our DFT calculations, increase the anharmonicity of the chemical bonds and enhance the phonon-phonon scattering. This, together with the introduced InAg.. point defects, further brings down the lattice thermal conductivity. The maximum thermoelectric figure of merit ZT is achieved at 773 K and increases from 0.3 for pristine AgBiSe2 to 0.7 for an optimal [In] = 0.015 doping, a more than two times enhancement.