Investigation of Mn Single and Co-Doping in Thermoelectric CoSb₃-Skutterudite: A Way Toward a Beneficial Composite Effect

Abstract

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 ≈ 4.7 mW/m K2 at 725 K for an unfilled skutterudite compound (PF = S 2σ with S, Seebeck coefficient; σ, electrical conductivity).

Reduced thermal conductivity and enhanced TE performance in CrSb2 via Fe-Bi co-substitution

“…A series of high-performing TE materials have been investigated i.e. Bi 2 Te 3 -based-materials [10][11][12][13], PbTe-based compounds [14][15][16][17][18], skutterudites [19][20][21][22][23], half-Heusler alloys [24][25][26][27][28][29], Zintl compounds [30][31][32][33][34][35][36][37][38] and so on. For room temperature applications, (Bi,Sb) 2 (Te,Se) 3 -based materials are recognized as the best system for decades due to their high ZT value which varied between 1 and 2 [39].…”