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Towards highly-efficient telluride-based thermoelectric materials

Abstract : The search to replace the toxic lead telluride (PbTe) alloys for thermoelectric applications in power generation has led to intensive studies of other telluride-based chalcogenide semiconductors. In this context, the binary SnTe has re-emerged over the last years as a promising candidate due to its rock-salt structure and electronic valence band structure similar to PbTe. Indium is a particularly intriguing dopant for SnTe as it leads to the appearance of a resonant level and superconductivity. Another noteworthy chalcogenide semiconductor, InTe has been recently shown to harbor promising thermoelectric properties due to its remarkably very low lattice thermal conductivity. The lack of detailed studies of its transport properties makes this compound a promising area of research in the field of thermoelectrics. In this work, we report on a detailed experimental and theoretical investigations of the transport properties of these two Te-based chalcogenides (XTe; X = Sn, In) in a wide range of temperatures (2 – 800 K). In a first part, the influence of indium on the transport properties of Sn1.03-xInxTe (0 ≤ x ≤ 40 %) is considered. The experimental results are supported by electronic band structure calculations performed using the Korringa-Kohn-Rostoker method with the coherent potential approximation (KKR-CPA). Both experimental and theoretical results demonstrate the resonant nature of In in Sn1.03Te with an optimum doping level of 2% giving the highest thermopower value for this system. Low-temperature transport properties measurements further highlight the complex evolution of the transport properties for low In contents. Investigations performed on InTe were performed on both single-crystalline and polycrystalline samples. A large single crystal of InTe was grown by the vertical Bridgman method. The possibility to control the defect concentration in InTe was considered though the saturation annealing method, carried out on the In-rich and Te-rich side of the solidus. Comparable to the peak ZT of ~ 0.7 at 780 K achieved in single-crystalline InTe within the ab plane, a maximum ZT of ~ 0.9 at 710 K was obtained in polycrystalline InTe.
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https://hal.univ-lorraine.fr/tel-02979619
Contributor : Shantanu Misra <>
Submitted on : Tuesday, October 27, 2020 - 11:22:16 AM
Last modification on : Wednesday, October 28, 2020 - 3:35:19 AM

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  • HAL Id : tel-02979619, version 1

Citation

Shantanu Misra. Towards highly-efficient telluride-based thermoelectric materials. Materials Science [cond-mat.mtrl-sci]. University of Lorraine, 2020. English. ⟨tel-02979619⟩

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