Improvement in thermoelectric properties of CaMnO3 by Bi doping and hot pressing

The polycrystalline of Ca1-xBixMnO3 (x = 0, 0.01, 0.02, 0.03, 0.04 and 0.05) thermoelectric materials were prepared by solid state reaction (SSR) and hot pressing (HP) methods. The crystallography and morphology were analysed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. It was found that the lattice parameters of Orthorhombic-perovskite increased with increasing Bi contents. The Seebeck coefficient shows negative value indicated n-type material and decreased with increasing Bi contents. The electrical resistivity decreased with increasing Bi content indicating metallic conduction as well but the thermal conductivity shows the semiconductor behaviour. The dimensionless figure of merit (ZT) value of Ca0.97Bi0.03MnO3 sample shows highest value about 0.065 at 473 K and the ZT value higher than un-doped CaMnO3 sample 95% at same temperature. (C) 2017 Elsevier Ltd. All rights reserved.