On the Design of High-Efficiency Thermoelectric Clathrates through a Systematic Cross-Substitution of Framework Elements

Authors

  • Xun Shi,

    1. Materials and Processes Laboratory General Motros R&D Center Warren, MI 48090 (USA)
    2. Optimal Incorporated Plymouth, MI 48170 (USA)
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  • Jiong Yang,

    1. State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of Ceramics, Chinese Academy of Sciences Shanghai 200050 (China)
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  • Shengqiang Bai,

    1. State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of Ceramics, Chinese Academy of Sciences Shanghai 200050 (China)
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  • Jihui Yang,

    Corresponding author
    1. Materials and Processes Laboratory General Motros R&D Center Warren, MI 48090 (USA)
    • Materials and Processes Laboratory General Motros R&D Center Warren, MI 48090 (USA).
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  • Hsin Wang,

    1. Materials Science and Technology Division Oak Ridge National Laboratory Oak Ridge, TN 37831 (USA)
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  • Miaofang Chi,

    1. Materials Science and Technology Division Oak Ridge National Laboratory Oak Ridge, TN 37831 (USA)
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  • James R. Salvador,

    1. Materials and Processes Laboratory General Motros R&D Center Warren, MI 48090 (USA)
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  • Wenqing Zhang,

    Corresponding author
    1. State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of Ceramics, Chinese Academy of Sciences Shanghai 200050 (China)
    • State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of Ceramics, Chinese Academy of Sciences Shanghai 200050 (China).
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  • Lidong Chen,

    Corresponding author
    1. State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of Ceramics, Chinese Academy of Sciences Shanghai 200050 (China)
    • State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of Ceramics, Chinese Academy of Sciences Shanghai 200050 (China).
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  • Winnie Wong-Ng

    1. Materials Science and Engineering Laboratory National Institute of Standards and Technology Gaithersburg, MD 20899 (USA)
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Abstract

Type I clathrates have recently been identified as prospective thermoelectric materials for power generation purposes due to their very low lattice thermal conductivity values. The maximum thermoelectric figure of merit of almost all type I clathrates is, however, less than 1 and occurs at, or above, 1000 K, making them unfavorable especially for intermediate temperature applications. In this report, the Zintl–Klemm rule is demonstrated to be valid for Ni, Cu, and Zn transition metal substitution in the framework of type I clathrates and offers many degrees of freedom for material modification, design, and optimization. The cross-substitution of framework elements introduces ionized impurities and lattice defects into these materials, which optimize the scattering of charge carriers by the substitution-induced ionized impurities and the scattering of heat-carrying lattice phonons by point defects, respectively, leading to an enhanced power factor, reduced lattice thermal conductivity, and therefore improved thermoelectric figure of merit. Most importantly, the bandgap of these materials can be tuned between 0.1 and 0.5 eV by adjusting the cross-substitution ratio of framework elements, making it possible to design clathrates with excellent thermoelectric properties between 500 and 1000 K.

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