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

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-x</sub>Sb<sub>x</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, z ≈ 1.6 × 10<sup>-3</sup> K<sup>-1</sup> (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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Publication Details

Journal
Nature Communications
Published
2025-03-26
DOI
https://doi.org/10.1038/s41467-025-57250-6
Citations
16
Primary Topic
Advanced Thermoelectric Materials and Devices
Type
article
Field-Weighted Citation Impact
8.28

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article

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

Gerda Rogl, Alexander Riss, Naoyuki Kawamoto, Nguyễn Duy Hiếu et al.
16 citations
Nature Communications
Advanced Thermoelectric Materials and Devices
8.28
article

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

Gerda Rogl, Alexander Riss, Naoyuki Kawamoto, Nguyễn Duy Hiếu, P. Rogl, Paweł Ziółkowski, Yuya Hattori, E. Bauer, Michael Parzer, Sanyukta Ghosh, Illia Serhiienko, Erhard Schafler, Eckhard Müller, Cédric Bourgès, Takao Mori, Fabian Garmroudi, Johannes de Boor, Gregor Oppitz, Sebastian Steyrer
article en
16 citations

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 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-x</sub>Sb<sub>x</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, z ≈ 1.6 × 10<sup>-3</sup> K<sup>-1</sup> (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.

Nature CommunicationsVol. 16(1)
University of Vienna (AT), TU Wien (AT), University of Tsukuba (JP), Justus-Liebig-Universität Gießen (DE), National Institute for Materials Science (JP), Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR) (DE), University of Duisburg-Essen (DE)
Lions Clubs International Foundation, Deutsche Forschungsgemeinschaft, Technische Universität Wien, Japan Science and Technology Agency, Technische Universität Wien Bibliothek, JST-Mirai Program
Affordable and clean energy
Openalex Percentile: Top 2%
Advanced Thermoelectric Materials and Devices
8.28
DOIOpen Access PDFOpenAlex
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