Atomistic study of an ideal metal/thermoelectric contact: The full-Heusler/half-Heusler interface

• Published in: APL materials Vol. 7; no. 1; pp. 013202 - 013202-7
• Main Authors: Spataru, Catalin D., He, Yuping, Léonard, François
• Format: Journal Article
• Language: English
• Published: AIP Publishing LLC 01.01.2019
• ISSN: 2166-532X; 2166-532X
• DOI: 10.1063/1.5052271

Half-Heusler alloys such as the (Zr,Hf)NiSn intermetallic compounds are important thermoelectric materials for converting waste heat into electricity. Reduced electrical resistivity at the hot interface between the half-Heusler material and a metal contact is critical for device performance; however, this is yet to be achieved in practice. Recent experimental work suggests that a coherent interface between half-Heusler and full-Heusler compounds can form due to diffusion of transition metal atoms into the vacant sublattice of the half-Heusler lattice. We study theoretically the structural and electronic properties of such an interface using a first-principles based approach that combines ab initio calculations with macroscopic modeling. We find that the prototypical interface HfNi2Sn/HfNiSn provides very low contact resistivity and almost ohmic behavior over a wide range of temperatures and doping levels. Given the potential of these interfaces to remain stable over a wide range of temperatures, our study suggests that full-Heuslers might provide nearly ideal electrical contacts to half-Heuslers that can be harnessed for efficient thermoelectric generator devices.