Dopant-segregation to grain boundaries controls electrical conductivity of n-type NbCo(Pt)Sn half-Heusler alloy mediating thermoelectric performance

Luo T, Serrano-Sanchez F, Bishara H, Zhang S, Villoro RB, Kuo JJ, Felser C, Scheu C, Snyder GJ, Best JP, Dehm G, Yu Y, Raabe D, Fu C, Gault B (2021)

Publication Type: Journal article

Publication year: 2021

Journal

Acta Materialia Elsevier

Book Volume: 217

Article Number: 117147

DOI: 10.1016/j.actamat.2021.117147

Abstract

Science-driven design of future thermoelectric materials requires a deep understanding of the fundamental relationships between microstructure and transport properties. Grain boundaries in polycrystalline materials influence the thermoelectric performance through the scattering of phonons or the trapping of electrons due to space-charge effects. Yet, the current lack of careful investigations on grain boundary-associated features hinders further optimization of properties. Here, we study n-type NbCo1-xPtxSn half-Heusler alloys, which were synthesized by ball milling and spark plasma sintering (SPS). Post-SPS annealing was performed on one sample, leading to improved low-temperature electrical conductivity. The microstructure of both samples was examined by electron microscopy and atom probe tomography. The grain size increases from ~230 nm to ~2.38 μm upon annealing. Pt is found within grains and at grain boundaries, where it locally reduces the resistivity, as assessed by in situ four-point-probe electrical conductivity measurement. Our work showcases the correlation between microstructure and electrical conductivity, providing opportunities for future microstructural optimization by tuning the chemical composition at grain boundaries.

Involved external institutions

Max-Planck-Institut für Eisenforschung GmbH (MPIE) / Max Planck Institute for Iron Research DE Germany (DE) Northwestern University US United States (USA) (US) Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen DE Germany (DE) Max-Planck-Institut für Chemische Physik fester Stoffe (MPI CPfS) / Max Planck Institute for Chemical Physics of Solids DE Germany (DE)

How to cite

APA:

Luo, T., Serrano-Sanchez, F., Bishara, H., Zhang, S., Villoro, R.B., Kuo, J.J.,... Gault, B. (2021). Dopant-segregation to grain boundaries controls electrical conductivity of n-type NbCo(Pt)Sn half-Heusler alloy mediating thermoelectric performance. Acta Materialia, 217. https://doi.org/10.1016/j.actamat.2021.117147

MLA:

Luo, Ting, et al. "Dopant-segregation to grain boundaries controls electrical conductivity of n-type NbCo(Pt)Sn half-Heusler alloy mediating thermoelectric performance." Acta Materialia 217 (2021).

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