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<p>Decoupling charge and heat transport is essential for optimizing thermoelectric materials. Strategies to inhibit lattice-driven heat transport, however, also compromise carrier mobility, limiting the performance of most thermoelectrics, including Fe<sub>2</sub>VAl Heusler compounds. Here, we demonstrate an innovative approach, which bypasses this tradeoff: via liquid-phase sintering, we incorporate the archetypal topological insulator Bi<sub>1−<i>x</i></sub>Sb<sub><i>x</i></sub> between Fe<sub>2</sub>V<sub>0.95</sub>Ta<sub>0.1</sub>Al<sub>0.95</sub> grains. Structural investigations alongside extensive thermoelectric and magneto-transport measurements reveal distinct modifications in the microstructure, a reduced lattice thermal conductivity and a simultaneously enhanced carrier mobility arising from topologically protected charge transport along the grain boundaries. This yields a huge performance boost, resulting in one of the highest figure of merits among both half- and full-Heusler compounds, <i>z</i>&#xa0;≈&#xa0;1.6&#xa0;×&#xa0;10<sup>−3</sup> K<sup>−1</sup> (<i>z</i><i>T</i>&#xa0;≈&#xa0;0.5) at 295 K. Our findings highlight the potential of topological-insulating secondary phases to decouple charge and heat transport and call for more advanced theoretical studies of multiphase composites.</p>

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Decoupled charge and heat transport in Fe2VAl composite thermoelectrics with topological-insulating grain boundary networks

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年3月26日

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  • Fabian Garmroudi,
  • Illia Serhiienko,
  • Michael Parzer,
  • Sanyukta Ghosh,
  • Pawel Ziolkowski,
  • Gregor Oppitz,
  • Hieu Duy Nguyen,
  • Cédric Bourgès,
  • Yuya Hattori,
  • Alexander Riss,
  • Sebastian Steyrer,
  • Gerda Rogl,
  • Peter Rogl,
  • Erhard Schafler,
  • Naoyuki Kawamoto,
  • Eckhard Müller,
  • Ernst Bauer,
  • Johannes de Boor,
  • Takao Mori

摘要

Decoupling charge and heat transport is essential for optimizing thermoelectric materials. Strategies to inhibit lattice-driven heat transport, however, also compromise carrier mobility, limiting the performance of most thermoelectrics, including Fe2VAl Heusler compounds. Here, we demonstrate an innovative approach, which bypasses this tradeoff: via liquid-phase sintering, we incorporate the archetypal topological insulator Bi1−xSbx between Fe2V0.95Ta0.1Al0.95 grains. Structural investigations alongside extensive thermoelectric and magneto-transport measurements reveal distinct modifications in the microstructure, a reduced lattice thermal conductivity and a simultaneously enhanced carrier mobility arising from topologically protected charge transport along the grain boundaries. This yields a huge performance boost, resulting in one of the highest figure of merits among both half- and full-Heusler compounds, z ≈ 1.6 × 10−3 K−1 (zT ≈ 0.5) at 295 K. Our findings highlight the potential of topological-insulating secondary phases to decouple charge and heat transport and call for more advanced theoretical studies of multiphase composites.