Improved thermoelectric performance in Pr and Sr Co-doped CaMnO3 materials

Abstract

The enhancement of thermoelectric performance should be a compromise of electrical as well as thermal transports with reasonably little reduction of thermopower. In this study, the effects of co-doping by rare earth Pr and alkaline earth Sr on perovskite Ca0.92-xPr0.08SrxMnO3 (x = 0, 0.01, 0.02, 0.03, 0.04) bulk materials are evaluated in terms of the phase composition, microstructure, grain combination, electrical transport as well as the thermal transport properties. The results show that perovskite type phases are reserved for the doped bulk materials. The bulk Material porosity can be decreased obviously and better grain interconnection is formed by introducing co-doping. The electrical conductivity is enhanced due to increased carrier concentration and mobility. The carriers for the intrinsic CaMnO3 and the co-doped Ca0.92-xPr0.08SrxMnO3 (x = 0, 0.01, 0.02, 0.03, 0.04) bulk materials follow the adiabatic polaron transport model; the activation energy as well as the band gap are reduced. The total thermal conductivity is further reduced by co-doping of Sr comparing with the Pr single-doped bulk materials. The co-doping is effective for further confining the thermal conduction. The ZT values of the co-doped samples are increased by 12.5%, 18.7%, 25% and 18.7% comparing with the Pr single-doped materials, respectively.