Synergistic band convergence and endotaxial nanostructuring: Achieving ultralow lattice thermal conductivity and high figure of merit in eco-friendly SnTe
Synergistic band convergence and endotaxial nanostructuring: Achieving ultralow lattice thermal conductivity and high figure of merit in eco-friendly SnTe
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协同能带会聚和内延纳米结构：在环保的 SnTe 中实现超低晶格热导率和高品质因数
DOI：
10.1016/j.nanoen.2019.104261
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发表时间：
2020-01-01
期刊：
影响因子：
17.6
通讯作者：
Tang, Guodong
中科院分区：
文献类型：
--
作者：
Li, Xiaotong;Liu, Jizi;Tang, Guodong
SnTe已成为PbTe发电应用的一种环境友好的替代品。在这里，我们通过价带会聚和内移纳米结构的协同作用，实现了SNTE的超低晶格热导率和高热电性能。DFT计算支持低Ge和Sb合金化导致SNTE中的能带收敛，从而显著提高Seebeck系数和功率因数。我们还提出了一种将内向Cu2Te纳米结构引入SNTE的相分离策略。内生Cu2Te纳米沉淀物使晶格热导率显著降低。Sn0.92Ge0.04Sb0.04Te-5%Cu2Te在873K下表现出0.27Wm(-1)K-1的超低晶格热导率，不仅低于SNTE的非晶态极限，而且与晶体结构复杂、非谐性强的热电材料相当。因此，通过协同优化SNTE的电和热输运特性，在873K时获得了非常高的优值系数(ZT)为1.5。如此高的ZT是通过采用简单、可控的一步工艺、无毒和低含量的元素掺杂而获得的。低含量贵金属掺杂可以有效地降低热电组件的成本，并有可能扩大其在各种热电发电机应用中的用途。这种ZT高、成本低的环保材料必将加速热电组件的广泛应用进程。
SnTe has emerged as an environmentally friendly alternative to PbTe for power generation application. Here, we achieve an ultralow lattice thermal conductivity and a high thermoelectric performance of SnTe via the synergy of valence band convergence and endotaxial nanostructuring. Low-content Ge and Sb alloying leads to band convergence in SnTe as supported by DFT calculations, thereby remarkably increasing Seebeck coefficient and power factor. We also propose a phase separation strategy to introduce endotaxial Cu2Te nanostructures to SnTe. Endotaxial Cu2Te nanoprecipitates cause the lattice thermal conductivity to reduce significantly. Sn0.92Ge0.04Sb0.04Te-5%Cu2Te exhibits an ultralow lattice thermal conductivity of 0.27 Wm(-1) K-1 at 873 K, which is not only lower than the amorphous limit of SnTe but also comparable with those of thermoelectric materials with complex crystal structures and strong anharmonicity. Consequently, a remarkably high figure of merit (ZT) of 1.5 at 873 K is achieved by synergistically optimizing the electrical and thermal transport properties of SnTe. Such remarkably high ZT is achieved by adopting a facile and controllable one-step process, nontoxic and low-content element doping. Low-content precious metal doping can effectively reduce the cost of thermoelectric modules and potentially expand their usefulness for various thermoelectric generator applications. The environmentally friendly material with high ZT and low cost can definitely accelerate the process of widespread use of thermoelectric modules.