Alloying and Doping Control in the Layered Metal Phosphide Thermoelectric CaCuP
Alloying and Doping Control in the Layered Metal Phosphide Thermoelectric CaCuP
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DOI：
10.1021/acsaelm.3c00828
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发表时间：
2023-09
影响因子：
4.7
通讯作者：
R. Quinn;R. Biswas;Jan-Willem G. Bos
中科院分区：
文献类型：
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作者：
R. Quinn;R. Biswas;Jan-Willem G. Bos
我们最近发现CaCuP是一种潜在的低成本、低密度热电材料，在792 K时zT = 0.5。其性能受到大的晶格热导率κL和固有的大p型掺杂水平的限制。在本文中，我们解决的热和电子的可调谐性的CaCuP。在CaCuP 1-xAsx系列的整个固溶体范围内，与As的等价合金化是可能的。这导致由于质量波动而导致的κL的降低，但也导致由于增加的Cu空位而导致的p型掺杂的有害增加，这阻止了zT的改善。相边界映射，利用从1：1：1化学计量的小偏差，被用来探索掺杂的可调性，发现增加p型掺杂要比降低掺杂水平容易得多。在单抛物线带近似下计算洛伦兹数，导致高掺杂样品的κL不切实际，与这些材料中的多带行为一致。总的来说，CaCuP和略微富集Cu的CaCu1.02P产生最佳性能，在873 K下zT接近0.6。
We recently identified CaCuP as a potential low cost, low density thermoelectric material, achieving zT = 0.5 at 792 K. Its performance is limited by a large lattice thermal conductivity, κL, and by intrinsically large p-type doping levels. In this paper, we address the thermal and electronic tunability of CaCuP. Isovalent alloying with As is possible over the full solid solution range in the CaCuP1–xAsx series. This leads to a reduction in κL due to mass fluctuations but also to a detrimental increase in p-type doping due to increasing Cu vacancies, which prevents zT improvement. Phase boundary mapping, exploiting small deviations from 1:1:1 stoichiometry, was used to explore doping tunability, finding increasing p-type doping to be much easier than decreasing the doping level. Calculation of the Lorenz number within the single parabolic band approximation leads to an unrealistic low κL for highly doped samples consistent with the multiband behavior in these materials. Overall, CaCuP and slightly Cu-enriched CaCu1.02P yield the best performance, with zT approaching 0.6 at 873 K.