Effect of double substitution of Ba and Ag on thermal transport of Ca3Co4O9-based thermoelectric oxide

Abstract

The Ba and Ag co-doped BaxAgyCa2.8Co4O9 thermoelectric bulk materials are fabricated by acid sol-gel and spark plasma sintering method. The phase compositions, microstructures and thermal transport properties of the resulting bulk materials are analyzed by X-ray diffraction, scanning electron microscopy and the thermal transport constant measurement apparatus. The results show that the thermal conduction behavior for the titled system can be effectively tuned by Ba and Ag co-doping, and the thermal conductivity could be reduced by increasing the Ba doping content. The analysis results show that the total thermal conduction suppressing comes from the lattice thermal conduction confinement. The Ba0.1Ag0.1Ca2.8Co4O9 bulk material is found to have the lowest thermal conductivity with total thermal conductivity and lattice thermal conductivity reaching 1.43 W/mK and 1.10 W/mK at 973 K, respectively.