Ternary Ag2Se1–xTex: A Near-Room-Temperature Thermoelectric Material with a Potentially High Figure of Merit,Inorganic Chemistry

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Ternary Ag2Se1–xTex: A Near-Room-Temperature Thermoelectric Material with a Potentially High Figure of Merit
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2021-09-02 , DOI: 10.1021/acs.inorgchem.1c01563
Jie Chen ₁ , Hualei Yuan ₂ , Yu-Ke Zhu ₃ , Kun Zheng ₂ , Zhen-Hua Ge ₃ , Jun Tang ₄ , Dali Zhou ₁ , Lei Yang ₁ , Zhi-Gang Chen ₅

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Discovering high-performance near-room-temperature thermoelectric materials is extremely imperative to widen the practical application in thermoelectric power generation and refrigeration. Here, ternary Ag₂Se_1–xTe_x (x = 0.1, 0.2, 0.3, 0.4, and 0.5) materials are prepared via the wet-mechanical alloying and spark plasma sintering process to investigate their near-room-temperature thermoelectric properties. From density functional theory calculation and single-parabolic-band modeling study, we found that the reduced contribution of Se 4p orbitals to the total density of states decreases the carrier effective mass with increasing Te content, which should enhance the theoretically maximum zT. These calculation results are also verified by the experimental results. Meanwhile, complex microstructures including dislocations, nanograins, high-density boundaries, Te_Se substitution, lattice distortions, and localized strain have been observed in ternary Ag₂Se_1–xTe_x. These complex microstructures strengthen phonon scattering and in turn lead to ultralow lattice thermal conductivity in the range of 0.21–0.31 W m^–1 K^–1 in ternary Ag₂Se_1–xTe_x at 300 K. Although the increased deformation potential suppresses the carrier mobility, benefiting from the engineered band structures and ultralow lattice thermal conductivity, a high zT of >1 can be potentially obtained in the ternary Ag₂Se_1–xTe_x with appropriate carrier concentration. This study indicates that ternary Ag₂Se_1–xTe_x is a promising candidate for near-room-temperature thermoelectric applications.

中文翻译：

三元 Ag2Se1–xTex：一种具有潜在高品质因数的近室温热电材料

发现高性能的近室温热电材料对于拓宽热电发电和制冷的实际应用至关重要。在这里，通过湿机械合金化和放电等离子体烧结工艺制备了三元 Ag ₂ Se _{1– x} Te _x ( x = 0.1、0.2、0.3、0.4 和 0.5) 材料，以研究它们的近室温热电性能。从密度泛函理论计算和单抛物线带建模研究中，我们发现随着 Te 含量的增加，Se 4p 轨道对总态密度的贡献降低，载流子有效质量降低，这应该提高理论上的最大zT. 这些计算结果也得到了实验结果的验证。同时，在三元Ag ₂ Se _1–_x Te _{x 中}观察到了复杂的微观结构，包括位错、纳米晶粒、高密度边界、Te _Se取代、晶格畸变和局部应变。这些复杂的微结构增强了声子散射，进而导致三元 Ag ₂ Se _1–_x Te _{x 中的}超低晶格热导率在 0.21–0.31 W m ^–1 K ^–1范围内在 300 K。虽然增加的变形势抑制了载流子迁移率，受益于工程能带结构和超低晶格热导率，但在具有适当载流子的三元 Ag ₂ Se _{1– x} Te _{x 中}可能获得 >1的高zT专注。该研究表明，三元 Ag ₂ Se _{1– x} Te _x是近室温热电应用的有希望的候选者。

更新日期：2021-09-20

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