High temperature thermoelectric properties of BaxSr2-xFeCoO6 double perovskites

In this study, environmentally benign BaxSr2-xFeCoO6 (BSFC) double perovskites are synthesized via solid-state reaction route for high-temperature thermoelectric applications. The crystal structure and morphology of the ceramic samples are analyzed using XRD and SEM, respectively. Rietveld refinement of XRD data confirms a cubic structure with Pmm space-group. High-temperature thermoelectric measurements exhibits that substituting Ba for Sr in Sr2FeCoO6 increases the Seebeck coefficient (S) but at the expense of the electrical conductivity (sigma). The highest Seebeck coefficient of 117 mu V/K has been observed in Ba0.5Sr1.5FeCoO6 at 910 K. Temperature-dependent electrical conductivity measurements indicates a semiconductor-to-metal like transition in all samples, with BSFC (x = 0.1) achieving the highest conductivity of 4 <bold>x</bold> 10(4) S m(-1) at similar to 623 K. The thermoelectric power factor has been enhanced by over 50% with Ba substitution in Sr2FeCoO6. Electron transport in these double perovskites is found to follow the small polaron hopping conduction mechanism.