Synthesis and thermoelectric properties of high-entropy half-Heusler MFe1-xCoxSb (M = equimolar Ti, Zr, Hf, V, Nb, Ta)
Synthesis and thermoelectric properties of high-entropy half-Heusler MFe1-xCoxSb (M = equimolar Ti, Zr, Hf, V, Nb, Ta)
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DOI：
10.1016/j.jallcom.2021.162045
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发表时间：
2021-10-06
影响因子：
6.2
通讯作者：
Reece, Michael J.
中科院分区：
文献类型：
--
作者：
Chen, Kan;Zhang, Ruizhi;Reece, Michael J.
高熵概念的应用已经为合金和陶瓷产生了许多有趣的结果。然而，关于高熵热电材料的报道却很少。采用简单的机械合金化方法成功合成了M位含有Ti、Zr、Hf、V、Nb和Ta等6种元素的单相高熵半Heusler化合物MFe 1-xCoxSb，并通过放电等离子烧结致密化后保持单相。多元素在样品中分布均匀。样品在1073 K氩气气氛中退火72 h后没有发生相分离，这可能是由于样品具有较高的构型熵。由于多元素引入的声子散射，MCoSb的晶格热导率被大大抑制，最低值为1.8- 1.5Wm（-1）K（-1）（300-923 K）。通过调节Fe/Co比，样品可以同时表现出n型和p型半导体特性。对于n型MCoSb和p型MFe 0.6Co 0.4Sb，分别实现了0.3和0.25的最大zT值。结果表明，高熵概念是一种很有前途的策略，可以扩展半Heusler材料的组成范围并调节其热电性能，这可能会应用于其他热电材料。(C)2021爱思唯尔有限公司版权所有。
The application of the high-entropy concept has generated many interesting results for both alloys and ceramics. However, there are very few reports on high entropy thermoelectric materials. In this work, a single phase high-entropy half-Heusler compound MFe1-xCoxSb with 6 equimolar elements (Ti, Zr, Hf, V, Nb and Ta) on the M site was successfully synthesized by a simple method of mechanical alloying, and the single phase was maintained after densification by spark plasma sintering. The multi-elements are homogenously distributed in the samples. The samples are stable and there is no phase separation after annealing at 1073 K in argon for 72 h, which could be attributed to their high configurational entropy. Due to the phonon scattering introduced by multi-elements, the lattice thermal conductivity is largely sup-pressed with a lowest value of similar to 1.8-1.5 Wm(-1)K(-1) (300-923 K) for MCoSb. By adjusting the Fe/Co ratio, the samples can show both n-type and p-type semiconductor behavior. Maximum zT values of 0.3 and 0.25 are achieved for n-type MCoSb and p-type MFe0.6Co0.4Sb, respectively. The results suggest that the high-entropy concept is a promising strategy to extend the composition range and tune the thermoelectric properties for half-Heusler materials, which could potentially be applied in other thermoelectric materials. (C) 2021 Elsevier B.V. All rights reserved.