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Mobility Ratio as a Probe for Guiding Discovery of Thermoelectric Materials: The Case of Half-Heusler PhaseScNiSb1−xTex
Physical Review Applied ( IF 4.6 ) Pub Date : 2021-04-28 , DOI: 10.1103/physrevapplied.15.044047
Kamil Ciesielski , Izabela Wolańska , Karol Synoradzki , Damian Szymański , Dariusz Kaczorowski

Analysis of bipolar thermal conductivity might be very useful in preliminary stages of thermoelectric materials discovery. Using its product—mobility ratio between electrons and holes—it is possible to choose the most promising compound from the series and pave the correct direction of doping. Current work presents positive verification of this approach for ScNiSb, which is anticipated to show superior mobility when tuned towards n-type behavior. In agreement with expectation, the mobility increases by an order of magnitude due to rising tellurium content in the ScNiSb1xTex series. The effect is most likely driven by change of the dominant charge carriers’ scattering mechanism from ionized impurity influence to point defect and acoustic phonon interaction. Simultaneously, due to a highly anisotropic conduction band, the effective mass of the carriers rises towards the n-type regime. These two effects lead to an improved thermoelectric power factor of electron-doped samples, up to 40μWK2cm1 at 740 K for ScNiSb0.85Te0.15. Based on this result, we suggest n-type doping for other rare-earth-based half-Heusler compounds. Representatives of this group exhibit the smallest lattice thermal conductivity in the pristine form among any half-Heusler thermoelectrics, and are anticipated to show comparably good electrical properties to ScNiSb due to their high mobility ratio in favor of electrons.

中文翻译:

迁移率作为指导热电材料发现的探针:以半霍斯勒相ScNiSb1-xTex为例

在热电材料发现的初步阶段,双极导热系数的分析可能非常有用。利用其乘积-电子与空穴之间的迁移率-可以从该系列中选择最有希望的化合物,并为掺杂的正确方向铺平道路。当前的工作对这种方法提出了积极的验证。SC,当调整为n型行为时,有望显示出出众的移动性。与预期一致,由于金属中碲含量的增加,迁移率增加了一个数量级。SC1个-XX系列。这种影响很可能是由主要电荷载流子的散射机制从离子化杂质影响到点缺陷和声子声子相互作用的变化所驱动的。同时,由于高度各向异性的导带,载流子的有效质量朝着n型态增加。这两个效应导致掺杂电子样品的热电功率因数提高,最高可达40μWK-2个厘米-1个 在740 K下 SC0.850.15。基于此结果,我们建议对其他基于稀土的半霍斯勒化合物进行n型掺杂。该组的代表在任何半霍斯勒热电元件中以原始形式显示出最小的晶格热导率,并且由于其对电子有利的高迁移率,预计与ScNiSb表现出相对较好的电性能。
更新日期:2021-04-29
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