In order to clarify the role of Sr doping in the themoelectric properties of Ca3Co4O9, Ca3-x SrxCo 4O9 samples were fabricated by uniaxial compression molding and sintering in atmosphere. Their thermoelectric properties and atomic-scale structures were investigated. Forx < 0:3, the dimensionless figure of merit (ZT) increases with x through a decrease in the thermal conductivity despite the nearly constant Seebeck coefficient and electrical resistivity. Scanning transmission electron microscopy images and energy-dispersive X-ray spectroscopy maps have revealed that Sr mainly substitutes in the Ca site in the rocksalt layer. These results suggest that Sr doping enhances ZT by decreasing in the rocksalt layer, but it does not significantly affect electrical properties because it is an isovalent substitution.
ASJC Scopus subject areas
- Physics and Astronomy(all)