Investigation of Mn Single and Co-Doping in Thermoelectric CoSb 3 -Skutterudite: A Way Toward a Beneficial Composite Effect
Résumé
We report here the first in-depth theoretical and experimental investigations of Mn substitution within the CoSb3-skutterudite. A systematic and comprehensive approach was employed to first determine the feasibility of single/cosubstitution for Mn with Te and then assess its effect. Subsequently, experimental realization of the samples was conducted. We were able to highlight a low solubility limit of Mn as a single dopant and provide evidence that the substitution stabilizes p-type conduction, as predicted via density functional theory calculations. Then, we reveal the prevalent formation of the composite MnTe/CoSb3-skutterudite phases instead of the expected favorable cosubstitution. This unexpected composite formation induces a beneficial effect, maximizing the Seebeck coefficient and leading to a record power factor (PF) of approximate to 4.7 mW/m K-2 at 725 K for an unfilled skutterudite compound (PF = S-2 sigma with S, Seebeck coefficient; s, electrical conductivity).
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