Tuning Crystal Structures and Thermoelectric Properties through Al Doping in ReSi1.75

Abstract

Binary rhenium silicide, ReSi1.75, and its aluminium‐doped variants have been synthesized. Their crystal structures were characterized by X‐ray diffraction, solved and refined through the use of superspace group models. The binary undoped ReSi1.75 is a commensurate (supercell) structure of the previously well‐known MoSi2‐type structure. Al doping renders an incommensurate structure that was solved and refined, and reported for the first time. The thermoelectric properties of these compounds were also measured, including their electrical resistivities, thermal conductivities, and Seebeck coefficients. Compared with the commensurate structure of binary ReSi1.75, the Al‐doped incommensurate phase exhibits lower lattice thermal conductivity, lower electrical resistivity, a higher Seebeck coefficient, and ultimately a much higher figure of merit (ZT). The cause of the structural incommensuration by Al doping was studied through the use of first‐principle calculations. The relationship between the incommensurability and the improved thermoelectric properties is also discussed.

Document Type

Article

DOI

https://doi.org/10.1002/ejic.201600792

Keywords

rhenium, x‐ray diffraction, thermoelectric materials, aluminium, Ab initio calculations

Publication Date

2016

Journal Title

European Journal of Inorganic Chemistry

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