Thermoelectric properties of the aliovalent half-Heusler alloy Zn 0.5 Ti 0.5 NiSb with intrinsic low thermal conductivity
Thermoelectric properties of the aliovalent half-Heusler alloy Zn 0.5 Ti 0.5 NiSb with intrinsic low thermal conductivity
复制标题
本征低导热率异价半霍斯勒合金Zn 0.5 Ti 0.5 NiSb的热电性能
DOI：
10.1039/d3ta04514e
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发表时间：
2023
影响因子：
11.9
通讯作者：
Bos, Jan-Willem G.
中科院分区：
文献类型：
--
作者：
Kennedy, Blair F.;Kimber, Simon A.;Checchia, Stefano;Shawon, A. K.;Zevalkink, Alexandra;Suard, Emmanuelle;Buckman, Jim;Bos, Jan-Willem G.
利用异价元素的混合物来实现价态平衡的电子态是半赫斯勒热电材料研究中迅速兴起的领域。在这里，我们报道了 Zn0.5Ti0.5NiSb，它是 ZnNiSb 和 TiNiSb 的组合，通过调整 Zn/Ti 比例可以制成 p 型和 n 型，分别在 793 K 时达到峰值 zT = 0.18，在 700 K 时达到 zT = 0.33。这些有希望的值是由低晶格热导率支撑的，340 K 时 κL = 2.7 W m−1 K−1，所有样品都相似，在 793 K 时降至 1.25 W m−1 K−1。输运数据显示 p 型和 n 型样品的加权电子迁移率相似，表明相似的 zT 应该是可能的。对于两种极性，都观察到向简并传导的转变，叠加在带隙 Eg = 0.4 eV 的本征半导体行为上。中子和同步加速器 X 射线衍射实验（包括总散射）表明不存在间隙金属，并且没有揭示强烈的局部结构变化。缺乏大量的质量无序和晶格应变表明键无序是低 κL 的可能根源。这项工作描述了一种新材料系统，并进一步深入了解异价合金对半霍斯勒结构的影响。
Using mixtures of aliovalent elements to achieve a valence balanced electronic state is a rapidly emerging area in half-Heusler thermoelectric materials research. Here, we report on Zn0.5Ti0.5NiSb, a combination of ZnNiSb and TiNiSb, which by adjusting the Zn/Ti-ratio can be made p- and n-type, achieving peak zT = 0.18 at 793 K and zT = 0.33 at 700 K, respectively. These promising values are underpinned by a low lattice thermal conductivity, κL = 2.7 W m−1 K−1 at 340 K, similar for all samples, decreasing to 1.25 W m−1 K−1 at 793 K. Transport data reveal similar weighted electronic mobilities for p- and n-type samples, suggesting similar zT should be possible. For both polarities, a transition to degenerate conduction is observed, superposed on intrinsic semiconducting behaviour with a bandgap Eg = 0.4 eV. Neutron and synchrotron X-ray diffraction experiments, including total scattering, indicate the absence of interstitial metals and do not reveal strong local structural variations. The absence of substantial mass disorder and lattice strain points towards bond disorder as a possible origin for the low κL. This work describes a new materials system and provides further insight into the impact of aliovalent alloying in the half-Heusler structure.