Double Half-Heuslers
Double Half-Heuslers
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DOI：
10.2139/ssrn.3339907
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发表时间：
2019-02
期刊：
影响因子：
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通讯作者：
Shashwat Anand;Max Wood;Yi Xia;C. Wolverton;G. J. Snyder
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文献类型：
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作者：
Shashwat Anand;Max Wood;Yi Xia;C. Wolverton;G. J. Snyder
自大约世纪前发现以来，多功能半赫斯勒半导体作为具有价态平衡组成的三组分系统（标称式XYZ）被广泛研究。从完全相同的元素和稳定性规则，我们探索了可能的四元双（X'X“Y2Z2，X2Y”Y“Z2，和X2Y2Z”Z“），三元（X2”X“Y3Z3）和四元（X3”X“Y4Z4）半赫斯勒化合物的更大的相空间。使用可靠的，第一原理热力学的选择（365）以前未探索的组成，我们预测更多的四元化合物（131）比那些预测或广泛报道的三元系统（84）。与最先进的三元半赫斯勒热电器件相比，其性能受到其固有的高热导率（κ）的限制，双半赫斯勒中的κ由较小的群速度声子主导，并受到无序散射的限制。合成了双半Heusler Ti2FeNiSb2，并证实其具有比TiCoSb显著更低的κ，从而为热电效率优化提供了更好的起点。
Summary Since their discovery around a century ago, multi-functional half-Heusler semiconductors have been studied extensively as three-component systems (nominal formula XYZ) with valence balanced compositions. From the very same set of elements and stability rules, we explore a much larger phase space of possible quaternary double (X′X″Y2Z2, X2Y′Y″Z2, and X2Y2Z′Z″), triple (X2′X″Y3Z3), and quadruple (X3′X″Y4Z4) half-Heusler compounds. Using reliable, first-principles thermodynamics on a selection (365) of previously unexplored compositions, we predict more quaternary compounds (131) than those predicted or reported extensively for the ternary systems (84). In comparison to state-of-the-art ternary half-Heusler thermoelectrics, for which performance is limited by their intrinsically high thermal conductivity (κ), κ in double half-Heuslers is dominated by smaller group velocity phonons and limited by disorder scattering. The double half-Heusler Ti2FeNiSb2 was synthesized and confirmed to have a significantly lower κ than TiCoSb, thereby providing a better starting point for thermoelectric efficiency optimization.