Thermoelectric properties of the lanthanum-doped Ca3Co4O9 prepared by a modified parallel flow co-precipitation method

ABSTRACT An improvement in the thermoelectric properties of calcium cobaltite ceramics (Ca3Co4O9) was demonstrated through a modified co-precipitation method and lanthanum doping. With highly reactive precursors derived from the modified method, the energy consumption was conserved due to an apparent decrease in calcination duration. The conventional sintering produced a layer structure with the interconnected grains and the pores, which simultaneously optimised the thermal and electrical conductivity. The thermoelectric property was improved by the combination of the special morphology and ion substitution. The figure of merit ZT reached 0.205 (600°C) which was a competitive value for polycrystalline Ca3Co4O9 ceramics. The study provided a potential route for scalable production of Ca3Co4O9 ceramics with low energy use and excellent performance.