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<p>Half-Heuslers emerged as promising candidates for medium- and high-temperature thermoelectric power generation. However, polycrystalline half-Heuslers inevitably suffer from the defect-dominated scattering of electrons that greatly limits the optimization of their electronic properties. Herein, high-quality TiCoSb-based single-crystals with a dimension above 1 cm have been obtained. Benefitting from the improved electron mobility, an average power factor of ~37 μW cm<sup>−1</sup> K<sup>−2</sup> in the temperature range between 307 and 973 K has been realized in the n-type single-crystalline Ti<sub>1-<i>x</i></sub>Nb<sub><i>x</i></sub>CoSb. In addition, Hf alloying results in the expansion of the weighted scattering phase space and enhances the anharmonic scattering rate, thereby effectively suppressing the lattice thermal conductivity. Eventually, co-doping of Nb/Ta and alloying of Hf effectively elevate the thermoelectric performance of TiCoSb single crystal, and a peak <i>zT</i> above 1.0 has been realized, which outperforms the previously reported polycrystalline (Ti, Zr, Hf)CoSb-based and ZrCoBi-based materials. Importantly, a single leg of TiCoSb-based single crystals exhibits a heat-to-electricity energy conversive efficiency of ~10.2% at a temperature difference of 700 K. Here, our findings reveal the promise of TiCoSb-based single crystals for thermoelectric power generation, and can potentially guide the future explorations of other single-crystalline half-Heuslers.</p>

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Superior electron transport in the single-crystalline TiCoSb-based half-Heuslers

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年2月24日

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  • Sheng Ye,
  • Shizhen Zhi,
  • Xiaojing Ma,
  • Xin Bao,
  • Peng Zhao,
  • Jinxuan Cheng,
  • Sichen Duan,
  • Chenhao Lin,
  • Zuoxu Wu,
  • Shanquan Chen,
  • Jiamin Qiu,
  • Li Yin,
  • Xuanhe Zhang,
  • Yifan Zhou,
  • Feng Jiang,
  • Zuhuang Chen,
  • Feng Cao,
  • Yuhao Fu,
  • Qian Zhang,
  • Jun Mao

摘要

Half-Heuslers emerged as promising candidates for medium- and high-temperature thermoelectric power generation. However, polycrystalline half-Heuslers inevitably suffer from the defect-dominated scattering of electrons that greatly limits the optimization of their electronic properties. Herein, high-quality TiCoSb-based single-crystals with a dimension above 1 cm have been obtained. Benefitting from the improved electron mobility, an average power factor of ~37 μW cm−1 K−2 in the temperature range between 307 and 973 K has been realized in the n-type single-crystalline Ti1-xNbxCoSb. In addition, Hf alloying results in the expansion of the weighted scattering phase space and enhances the anharmonic scattering rate, thereby effectively suppressing the lattice thermal conductivity. Eventually, co-doping of Nb/Ta and alloying of Hf effectively elevate the thermoelectric performance of TiCoSb single crystal, and a peak zT above 1.0 has been realized, which outperforms the previously reported polycrystalline (Ti, Zr, Hf)CoSb-based and ZrCoBi-based materials. Importantly, a single leg of TiCoSb-based single crystals exhibits a heat-to-electricity energy conversive efficiency of ~10.2% at a temperature difference of 700 K. Here, our findings reveal the promise of TiCoSb-based single crystals for thermoelectric power generation, and can potentially guide the future explorations of other single-crystalline half-Heuslers.