Utilization of doping and compositing strategy for enhancing the thermoelectric performance of CaMnO3 perovskite

Abstract

The performance of high-temperature thermoelectric material CaMnO₃ is primarily limited by its high electrical resistivity and thermal conductivity. In this study, we synergistically optimized its electrical and thermal transport properties by employing a combination of doping and compositing strategies. The results suggest that Yb doping promotes the transfer of electrons to the Mn d orbital and facilitates the double exchange interactions between neighbor Mn³⁺ and Mn⁴⁺, leading to decreased electrical resistivity and a transition of electron transport mechanism from semiconductor to metal. The further addition of CoAl₂O₄ nanoparticles improves the Seebeck coefficient by reducing carrier concentration and increasing electron scattering, ultimately enhancing the power factor. Meanwhile, the fluctuations in atomic mass and increased interface density strengthen the interface phonon scattering, which results in a significant reduction in lattice thermal conductivity. As a result, the Ca_0.95Yb_0.05MnO₃ with 2 wt.% CoAl₂O₄ nanoparticles exhibits a maximum ZT value of 0.12 at 850 K, representing a 180% improvement compared to the pristine material. This study highlights the effectiveness of the combined doping and compositing strategy in enhancing the thermoelectric performance of CaMnO₃ materials and offers a promising approach for optimizing other oxide thermoelectric materials.