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arXiv · 2006.03234

Anomalous dependence of thermoelectric parameters on carrier concentration and electronic structure in Mn-substituted Fe2CrAl Heusler alloy

Kavita Yadav·Saurabh Singh·Omprakash Muthuswamy·Tsunehiro Takeuchi·K. Mukherjee
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Abstract

We investigate the high temperature thermoelectric properties of Heusler alloys Fe2-xMnxCrAl (0<x<1). Substitution of 12.5% Mn at Fe-site (x = 0.25) causes a significant increase in high temperature resistivity (\r{ho}) and an enhancement in the Seebeck coefficient (S), as compared to the parent alloy. However, as the concentration of Mn is increased above 0.25, a systematic decrement in the magnitude of both parameters is noted. These observations have been ascribed (from theoretical analysis) to a change in band gap and electronic structure of Fe2CrAl with Mn-substitution. Due to absence of mass fluctuations and lattice strain, no significant change in thermal conductivity is seen across this series of Heusler alloys. Additionally, S drastically changes its magnitude along with a crossover from negative to positive above 900 K, which has been ascribed to the dominance of holes over electrons in high temperature regime. In this series of alloys, S and \r{ho} shows a strong dependence on the carrier concentration and strength of d-d hybridization between Fe/Mn and Cr atoms.

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Kavita Yadav, Saurabh Singh, Omprakash Muthuswamy, Tsunehiro Takeuchi, K. Mukherjee. 2020-06-05. Anomalous dependence of thermoelectric parameters on carrier concentration and electronic structure in Mn-substituted Fe2CrAl Heusler alloy. https://doi.org/10.1080/14786435.2021.1994161

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