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

Fabian Garmroudi ; Illia Serhiienko SAMURAI ORCID (National Institute for Materials Science) ; Michael Parzer ; Sanyukta Ghosh ; Pawel Ziolkowski ; Gregor Oppitz ; Hieu Duy Nguyen ; Cédric Bourgès ORCID (National Institute for Materials Science) ; Yuya Hattori SAMURAI ORCID (National Institute for Materials Science) ; Alexander Riss ; Sebastian Steyrer ; Gerda Rogl ; Peter Rogl ; Erhard Schafler ; Naoyuki Kawamoto SAMURAI ORCID (National Institute for Materials Science) ; Eckhard Müller ; Ernst Bauer ; Johannes de Boor ; Takao Mori SAMURAI ORCID (National Institute for Materials Science)

Nature Communications--Decoupled charge and heat transport in Fe2VAl composite thermoelectrics with topological-insulating grain boundary networks.pdf
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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. Decoupled charge and heat transport in Fe2VAl composite thermoelectrics with topological-insulating grain boundary networks. Nature Communications. 2025, 16 (1), 2976. https://doi.org/10.1038/s41467-025-57250-6

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(abstract)

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.

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Keyword: thermoelectric

Date published: 2025-03-26

Publisher: Springer Science and Business Media LLC

Journal:

  • Nature Communications (ISSN: 20411723) vol. 16 issue. 1 2976

Funding:

  • MEXT | Japan Science and Technology Agency JPMJMI19A1
  • Lions Clubs International Foundation
  • Lions Club Wien St. Stephan
  • Deutsche Forschungsgemeinschaft 520487260

Manuscript type: Publisher's version (Version of record)

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First published URL: https://doi.org/10.1038/s41467-025-57250-6

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Updated at: 2025-11-10 16:30:43 +0900

Published on MDR: 2025-11-10 16:25:02 +0900

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