High Thermoelectric Performance in n-Type Degenerate ZrNiSn-Based Half-Heusler Alloys Driven by Enhanced Weighted Mobility and Lattice Anharmonicity,ACS Applied Energy Materials

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High Thermoelectric Performance in n-Type Degenerate ZrNiSn-Based Half-Heusler Alloys Driven by Enhanced Weighted Mobility and Lattice Anharmonicity
ACS Applied Energy Materials ( IF 5.4 ) Pub Date : 2021-03-17 , DOI: 10.1021/acsaem.0c03152
Kishor Kumar Johari _{1,

2} , Ruchi Bhardwaj _{1,

2} , Nagendra S. Chauhan ₃ , Sivaiah Bathula _{1,

2,

4} , Sushil Auluck ₁ , S. R. Dhakate _{1,

2} , Bhasker Gahtori _{1,

2}

Affiliation

ZrNiSn-based half-Heusler (HH) alloys are well-established alloys for n-type mid-temperature thermoelectric applications because of their chemical and thermal stability and narrow band gap driven semiconducting behavior. Here, we observed a high figure of merit, ZT ∼ 1, at 873 K in aliovalent Nb-doped composition Zr_1–xNb_xNiSn (x = 0–0.035) for x = 0.03 HH alloy prepared by employing a combination of arc-melting and spark plasma sintering. The high figure of merit is attributed to synergistic enhancement of the power factor with thermal conductivity reduction. Further, the enhancement of the power factor is correlated with the improved weighted mobility and reduction in thermal conductivity is analyzed in the framework of the model based on the theories of Callaway, Slack, and Abeles. The results are corroborated theoretically to establish the efficacy of Nb doping in ZrNiSn within semimetallic regimes for ZT enhancement. The synthesized Hf-free HH alloys establish Nb as an effective dopant for attaining high-ZT and cost-efficient HH-based n-type TE material in a mid-temperature regime for power generation application.

中文翻译：

增强的加权迁移率和晶格非谐性驱动的n型简并ZrNiSn基半霍斯勒合金的高热电性能

ZrNiSn基半霍斯勒（HH）合金由于其化学和热稳定性以及窄带隙驱动的半导体行为，因此是用于n型中温热电应用的公认合金。在这里，我们观察到的优点的高的数字，ZT在异价掺杂Nb的组成〜1中，在873K下的Zr _{1- X}的Nb _X NISN（X = 0-0.035）为X= 0.03 HH合金，是通过电弧熔化和火花等离子烧结相结合而制得的。高品质因数归因于功率因数与导热系数降低的协同增强。此外，功率因数的提高与加权加权迁移率的提高相关，并且基于Callaway，Slack和Abeles的理论在模型框架内分析了导热系数的降低。结果证实理论上为半金属政权内建立ZrNiSn铌掺杂的功效ZT提高。合成的不含Hf的HH合金将Nb确立为一种有效的掺杂剂，可在发电应用的中温条件下获得高ZT和经济高效的HH基n型TE材料。

更新日期：2021-04-26

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