Structural, electronic, and thermoelectric properties of La₂CuBiS₅

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• 作者：Gui Yang 杨癸 ; Yanhong Yao 姚艳红 ; Dongwei Ma 马东伟
• 关键词：chemical bond ; electronic structure ; thermoelectric properties
• 刊名：Science China Materials
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：60
• 期：2
• 页码：151-158
• 全文大小：2512KB
• 刊物类别：Materials Science, general; Chemistry/Food Science, general;
• 刊物主题：Materials Science, general; Chemistry/Food Science, general;
• 出版者：Science China Press
• ISSN：2199-4501
• 卷排序：60

文摘

The basic physical properties of La₂CuBiS₅ are studied by the first-principle calculations and the semiclassical Boltzmann theory. Charge density difference calculations show that electrons accumulate between Bi–S atoms, indicating considerable covalent bonding of Bi and S atoms. A similar charge density difference indicates that the Cu–S bonds also exhibit covalent character. The calculated minimum thermal conductivity of La₂CuBiS₅ is low, which is conducive to its use as a thermoelectric material. Owing to a bipolar effect, induced by thermal excitation, the material’s Seebeck coefficient decreases sharply at T = 800 K. For the n-type and p-type doping conditions, the largest values of S2σ/τ were calculated as −1.71×1011 and 1.837×1011 W K−2 ms−1, respectively. The combination of a large dispersion and a high band degeneracy along the Γ-Y direction in the band structure simultaneously induces the highest S_y value and a high σ/τ_y value. Thus, the thermoelectric performance of La₂CuBiS₅ is anisotropic and most favorable along the y direction.