A high throughput search for efficient thermoelectric half-Heusler compounds,Journal of Materials Chemistry A

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A high throughput search for efficient thermoelectric half-Heusler compounds
Journal of Materials Chemistry A ( IF 10.7 ) Pub Date : 2020-11-11 , DOI: 10.1039/d0ta06810a
Parul R. Raghuvanshi _{1,

2,

3,

4} , Suman Mondal _{1,

2,

3,

4} , Amrita Bhattacharya _{1,

2,

3,

4}

Affiliation

Half-Heusler compounds have emerged as promising thermoelectric materials that offer huge compositional space to tune their thermoelectric performance. A class of stable half Heusler compounds formed from elements of three specific groups in the periodic table viz. X_pX′_1−pY_qY′_1−qZ_rZ′_1−r (with X, X′ = Ti, Zr, Hf; Y, Y′ = Ni, Pd, Pt and Z, Z′ = Ge, Sn, Pb and p, q, r = 0, 0.25, 0.75 and 1) via various stoichiometric isoelectronic elemental substitutions at the X, Y and Z sites respectively, is investigated. Intelligent filters are employed at each step of our high throughput density functional theory calculations to filter compounds with improved figures of merit. While confirming several known results, the calculations also reveal unknown pathways to improve the thermoelectric performance of the compound class. The 50% X and Z site substitutions of the parent Heusler have been individually found to marginally enhance the power factor for both p- and n-type doping, while leading to considerable enhancement in the figure of merit (by ∼24%) specifically. This is due to lowering of the lattice thermal conductivity stemming from the increase in lattice disorder in approximately the same cell volume. Furthermore, the present study confirms the experimental scenario that Y site substitution does not lead to enhancement of the power factor because of the breaking of band degeneracies at the high symmetry points. This work will serve as a consolidated cost effective guideline for experimentalists working with this compound class on enhancing the power factor and figure of merit of the compositions.

中文翻译：

高通量寻找高效热电半霍斯勒化合物

Half-Heusler化合物已成为有前途的热电材料，可提供巨大的成分空间来调节其热电性能。由周期表中三个特定基团的元素形成的一类稳定的半Heusler化合物，即。X _p X' _{1- p} ý _q Y'_{的1- q} ż _[R Z' _{1- [R}（其中X，X'=钛，锆，铪; Y，Y'=的Ni，Pd，Pt和Z，Z'= Ge，Sn，Pb and p，q，r = 0，0.25，0.75 and 1）通过研究了分别在X，Y和Z位的各种化学计量的等电子元素取代。在我们的高通量密度泛函理论计算的每个步骤中，都会使用智能过滤器来过滤具有改进品质因数的化合物。在确认了几个已知结果的同时，计算还揭示了改善化合物类热电性能的未知途径。单独发现母体赫斯勒的50％X和Z位点置换可以略微提高p型和n型掺杂的功率因数，同时特别地提高了品质因数（约24％）。这是由于在大致相同的电池体积中晶格无序的增加而导致的晶格热导率的降低。此外，本研究证实了实验场景，即由于高对称点处的带简并性断裂，Y位取代不会导致功率因数提高。这项工作将作为针对使用该化合物类以提高组合物的功率因数和品质因数的实验者的综合成本有效指南。

更新日期：2020-11-22

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