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Compositional Fluctuations Locked by Athermal Transformation Yielding High Thermoelectric Performance in GeTe
Advanced Materials ( IF 29.4 ) Pub Date : 2020-11-20 , DOI: 10.1002/adma.202005612
Yi‐Fen Tsai, Pai‐Chun Wei, Liuwen Chang, Kuang‐Kuo Wang, Chun‐Chuen Yang, Yen‐Chung Lai, Cheng‐Rong Hsing, Ching‐Ming Wei, Jian He, G. Jeffrey Snyder, Hsin‐Jay Wu

Phase transition in thermoelectric (TE) material is a double‐edged sword—it is undesired for device operation in applications, but the fluctuations near an electronic instability are favorable. Here, Sb doping is used to elicit a spontaneous composition fluctuation showing uphill diffusion in GeTe that is otherwise suspended by diffusionless athermal cubic‐to‐rhombohedral phase transition at around 700 K. The interplay between these two phase transitions yields exquisite composition fluctuations and a coexistence of cubic and rhombohedral phases in favor of exceptional figures‐of‐merit zT. Specifically, alloying GeTe by Sb2Te3 significantly suppresses the thermal conductivity while retaining eligible carrier concentration over a wide composition range, resulting in high zT values of >2.6. These results not only attest to the efficacy of using phase transition in manipulating the microstructures of GeTe‐based materials but also open up a new thermodynamic route to develop higher performance TE materials in general.

中文翻译:

非热转变锁定的组分涨落在GeTe中产生高热电性能

热电(TE)材料中的相变是一把双刃剑-在应用中不希望设备运行,但电子不稳定附近的波动是有利的。在这里,Sb掺杂用于引发自发的成分波动,表现出GeTe中的向上扩散,否则在700 K左右被无扩散无热立方到菱形的相变所暂停。这两个相变之间的相互作用产生了精美的成分波动和共存立方和菱面体相的变化,有利于优异的品质因数zT。具体而言,通过Sb 2 Te 3使GeTe合金化在很大的组成范围内保持合格的载流子浓度的同时,显着抑制了热导率,导致> 2.6的高zT值。这些结果不仅证明了使用相变来处理基于GeTe的材料的微观结构的功效,而且开辟了一条新的热力学途径来开发性能更高的TE材料。
更新日期:2021-01-04
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