Charge compensation weakening ionized impurity scattering and assessing the minority carrier contribution to the Seebeck coefficient in Pb-doped Mg3Sb2 compounds.
Charge compensation weakening ionized impurity scattering and assessing the minority carrier contribution to the Seebeck coefficient in Pb-doped Mg3Sb2 compounds.
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DOI：
10.1039/d0cp00266f
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发表时间：
2020-03
期刊：
影响因子：
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通讯作者：
Qiang Zhang;Jichong Hou;Jianfeng Fan;Shaoping Chen;Wenhao Fan;Hua Zhang;Wen-xian Wang;Yucheng Wu;Bingshe Xu
中科院分区：
文献类型：
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作者：
Qiang Zhang;Jichong Hou;Jianfeng Fan;Shaoping Chen;Wenhao Fan;Hua Zhang;Wen-xian Wang;Yucheng Wu;Bingshe Xu
本工作报道了p型铅掺杂的Mg₃(₁₊ₓ)Sb₂₋ᵧPbᵧ（0.02 ≤ x ≤ 0.08；0 ≤ y ≤ 0.02）化合物中的电输运和热输运过程。低能电子受体缺陷镁空位易于形成，其可提供空穴并使Mg₃Sb₂基体中实现p型输运。然而，随着过量镁的增加，输运行为从p型转变为n型，这由霍尔系数和塞贝克系数协同体现。这表明了镁在调节原始Mg₃Sb₂化合物的载流子类型和浓度方面的有效作用。当用铅替代锑时，空穴浓度略有增加，并且室温下迁移率大幅提高了133%。迁移率的显著提高归因于电离杂质散射的减弱，这是由铅掺杂导致的浓度降低所引起的。因此，功率因数在室温下提高了146%。结果，在约300 K时，铅掺杂样品的热电优值ZT比原始样品大1.8倍。此外，根据少数载流子对整体塞贝克系数的影响，对电学性质所揭示的非简并输运行为进行了简单分析。本研究提出了一种提高迁移率的电荷补偿新策略以及一种指导预测Mg₃Sb₂基化合物和其他潜在热电材料中双极传导起始的简单方法。
This work reports the electrical and thermal transport processes in p-type Pb-doped Mg3(1+x)Sb2-yPby (0.02 ≤ x ≤ 0.08; 0 ≤ y ≤ 0.02) compounds. Low-energy electron acceptor defects Mg vacancies are easy to form, which can provide holes and make p-type transport in the Mg3Sb2 matrix. However, with an increase in excess Mg, the transport behavior changes from p type to n type as manifested synergistically by both the Hall coefficient and Seebeck coefficient. This indicates the effective role of Mg in tuning carrier type and concentration for a pristine Mg3Sb2 compound. Upon substitution of Sb by Pb, the hole concentration slightly increases, and mobility is greatly improved by 133% at room temperature. The significant increase in mobility is attributed to the weakening ionized impurity scattering, stemming from the decreasing concentration induced by Pb doping. Thus, the power factor is enhanced with a 146% improvement at room temperature. Consequently, the figure of merit ZT of the Pb-doped sample is 1.8 times larger than the pristine one at around 300 K. Moreover, the non-degenerate transport behavior revealed by electrical properties is simply analyzed regarding the effects of minority carriers on the overall Seebeck coefficient. This study proposes a new strategy of charge compensation for improving mobility and a simple way to guide the prediction about the onset of bipolar conduction for Mg3Sb2-based compounds and other potential thermoelectric materials.