Composite design of half-Heusler compounds to enhance the thermoelectric performance

R. Hatami Naderloo1*, R. He1, K. Nielsch1, R. Bueno Villoro2, D. A. Mattlat3, S. Zhang3, C. Scheu3, G. J. Snyder4, H. Zhu5, Sh. Song5, Zh. Ren6

1Leibniz-Institut für Festkörperund Werkstoffforschung, Dresden, Germany

2Technical University of Denmark, Copenhagen, Denmark

3Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany

4Northwestern University, Illinois, USA

5Department of Physics and Texas Center for Superconductivity, University of Houston

*E-mail of the corresponding author: r.hatami.naderloo@ifw-dresden.de

Thermoelectric materials demand intricate microstructures to optimize power conversion efficiency. While grain boundaries (GBs) traditionally reduce thermal conductivity in nanocrystalline materials, they often impede electrical conductivity.

Recent research, however, demonstrates that elemental segregation at GBs can render them electrically conductive, enhancing thermoelectric properties. This study introduces independent doping of GBs in p-type RFeSb (R: Nb and Ta) alloys using InSb.

This selective modification of GB chemistry, without increasing carrier concentration in the matrix, successfully increases power factor and zT. The findings highlight the potential of overcoming the negative impact of GBs on power factor through GB engineering.

References

[1] [1] H. Zhu, et al., Discovery of TaFeSb-based half-Heuslers with high thermoelectric performance, Nature Communications, volume 10, Article number: 270, (2019)

[2] H. Zhu, et al., Half-Heusler alloys as emerging high-power density thermoelectric cooling materials; Nature Communications volume, 14, Article number: 3300 (2023)

[3] R. Bueno Villoro, et al., Grain Boundary Phases in NbFeSb Half‐Heusler Alloys: A New Avenue to Tune Transport Properties of Thermoelectric Materials, Advanced Energy Materials, 2204321, (2023)

[4] R. Bueno Villoro, R. Hatami Naderloo, et al., Composite design of half-Heusler thermoelectrics: Selective doping of grain boundary phases in NbFeSb by InSb, Materials Today Physics, 101240, (2023)