Two mixed-anion semiconductors in the Ba–Sn–Te–S system with low thermal conductivity

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Article
Citation
Guo, W., Huang, Q., Zhang, W.-L., Chen, D.-G., Chen, A., Ang, E. H., Cui, H.-H., Luo, Z.-Z., & Zou, Z. (2023). Two mixed-anion semiconductors in the Ba–Sn–Te–S system with low thermal conductivity. ACS Applied Energy Materials, 6(4), 2508-2514. https://doi.org/10.1021/acsaem.2c03941
Author
Guo, Weiping
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Huang, Qing
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Zhang, Wei-Long
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Chen, Da-Gui
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Chen, Anita
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Ang, Edison Huixiang 
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Cui, Hong-Hua
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Luo, Zhong-Zhen
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Zou, Zhigang
Abstract
We synthesized two mixed-anion tin chalcogenides, Ba5Sn2Te1.327S7.673 (1) and Ba7Sn3Te0.839S12.161 (2), by a typical high-temperature solid-state reaction using an evacuated silica tube for the first time in the system of Ba–Sn–Q (Q = S1–xTex; 0 ≤ x ≤ 1). Compound 1 crystallizes in the monoclinic space group P21/c with unit cell parameters of a = 17.501(5) Å, b = 8.908(2) Å, c = 12.508(3) Å, and Z = 4. Compound 2 has an orthorhombic space group Pnma with a = 12.386(5) Å, b = 24.17(2) Å, c = 8.872(4) Å, and Z = 4. The structures of compounds 1 and 2 are both zero-dimensional (0D), and the formulas can be written as Ba5(SnIVQ4)2Q and Ba7(SnIVQ4)3Q with Sn/Q ratios of 2/9 and 3/13, respectively. Compounds 1 and 2 exhibit Q2– anion units, which is unique among Ba–Sn−Q compounds due to the [SnQ4] tetrahedra and low Sn/Q ratios. The phonon transport can be significantly scattered because the weakly bond Ba atom and highly distorted [SnQ4] tetrahedra can enhance the lattice anharmonicity. As a result, compounds 1 and 2 have low lattice thermal conductivity (κlat) values of ∼0.3–0.4 W m–1 K–1 in the range of 300 to 773 K, which results in a design strategy as thermoelectric materials.
Keywords
Date Issued
2023
Publisher
American Chemical Society
Journal
ACS Applied Energy Materials
DOI
10.1021/acsaem.2c03941