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Issue 29, 2020
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Thermoelectric properties of n-type half-Heusler NbCoSn with heavy-element Pt substitution

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Abstract

Half-Heusler compounds with a valence electron count of 18, including ZrNiSn, ZrCoSb, and NbFeSb, are good thermoelectric materials owing to favorable electronic structures. Previous computational studies had predicted a high electrical power factor in another half-Heusler compound NbCoSn, but it has not been extensively investigated experimentally. Herein, the synthesis, structural characterization, and thermoelectric properties of the heavy-element Pt-substituted NbCoSn compounds are reported. Pt is found to be an effective substitute enabling the optimization of electrical power factor and simultaneously leading to a strong point defect scattering of phonons and the suppression of lattice thermal conductivity. Post-annealing significantly improves the carrier mobility, which is ascribed to the decreased grain boundary scattering of electrons. As a result, a maximum power factor of ∼3.4 mW m−1 K−2 is obtained at 600 K. In conjunction with the reduced lattice thermal conductivity, a maximum figure of merit zT of ∼0.6 is achieved at 773 K for the post-annealed NbCo0.95Pt0.05Sn, an increase of 100% compared to that of NbCoSn. This work highlights the important roles that the dopant element and microstructure play in the thermoelectric properties of half-Heusler compounds.

Graphical abstract: Thermoelectric properties of n-type half-Heusler NbCoSn with heavy-element Pt substitution

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Supplementary files

Article information


Submitted
04 May 2020
Accepted
30 Jun 2020
First published
14 Jul 2020

This article is Open Access

J. Mater. Chem. A, 2020,8, 14822-14828
Article type
Paper

Thermoelectric properties of n-type half-Heusler NbCoSn with heavy-element Pt substitution

F. Serrano-Sánchez, T. Luo, J. Yu, W. Xie, C. Le, G. Auffermann, A. Weidenkaff, T. Zhu, X. Zhao, J. A. Alonso, B. Gault, C. Felser and C. Fu, J. Mater. Chem. A, 2020, 8, 14822
DOI: 10.1039/D0TA04644B

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