High temperature thermoelectric properties of BaxSr2-xFeCoO6 double perovskites

Abstract In this study, environmentally benign Ba x Sr 2-x FeCoO 6 (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 Pm3̅m space-group. High-temperature thermoelectric measurements exhibits that substituting Ba for Sr in Sr 2 FeCoO 6 increases the Seebeck coefficient (S) but at the expense of the electrical conductivity ( σ ). The highest Seebeck coefficient of 117 μV/K has been observed in Ba 0.5 Sr 1.5 FeCoO 6 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 × 10 4 S m −1 at ∼623 K. The thermoelectric power factor has been enhanced by over 50% with Ba substitution in Sr 2 FeCoO 6 . Electron transport in these double perovskites is found to follow the small polaron hopping conduction mechanism.