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Thermoelectric properties of marcasite-type compounds MSb2 (M = Ta, Nb): a combined experimental and computational study

Year: 2025
Type: article
Abstract: Here, we investigate the thermoelectric properties of the marcasite-type compounds MSb2 (M = Ta, Nb) in the temperature range of 310–730 K. These compounds were synthesized by a solid-state reaction followed by the spark plasma sintering process. The Rietveld refinement method confirms the monoclinic phase with space group C2/m for both compounds. The observed values of Seebeck coefficients exhibit non-monotonic behaviour in the studied temperature range, with the maximum magnitude of −14.4 and −22.7 µV K−1 for TaSb2 and NbSb2, respectively at ∼444 K. The negative sign of S in the full temperature window signifies the n-type behaviour of these compounds. Both electrical and thermal conductivities show decreasing trends with increasing temperature. The experimentally observed thermoelectric properties are understood through the first-principles DFT and Boltzmann transport equation. A pseudogap in the density of states around the Fermi level characterizes the semimetallic behaviour of these compounds. The multi-band electron and hole pockets were found to be mainly responsible for the temperature dependence of transport properties. The experimental power factors are found to be ∼0.09 and ∼0.42 mW m−1 K−2 at 300 K for TaSb2 and NbSb2, respectively. We found that there is much room for improvement of power factor by tuning carrier concentration. The DFT-based calculations predict the maximum possible power factors at fairly high doping concentrations. The present study suggests that the combined DFT and Boltzmann transport theory are found to be reasonably good at explaining the experimental transport properties, and moderate power factors are predicted.
DOI: 10.1088/1361-648x/adb409
Authors: Shamim Sk, Naoki Sato, Takao Mori
Language: English
Open Access status: bronze
OpenAlex ID: W4407268285
FWCI: 0.2
Cites: 72
Cited by: 1
Related to: 10