Effect of erbium substitution on thermoelectric properties of complex oxide Ca3Co2O6 at high temperatures

Polycrystalline particles of Ca3-xErxCo2O6 (x=0.0, 0.15, 0.3, 0.45 and 0.6) were synthesized using sol-gel method combined with Low Temperature Sintering procedure (LTS) to evaluate the effect of Er substitution on the thermoelectric properties of Ca3Co2O6. The crystal structure and microstructure were investigated using X-ray diffraction, infrared spectroscopy and scanning electron microscope. The electrical conductivity and Seebeck coefficient of the complex oxides were measured from 300 to 1073 K. The results showed that all the samples were p-type semiconductors. The electrical conductivity increased with the increase in temperature. Er substitutions at Ca site affected carrier concentrations and carrier mobility, resulting an increase in Seebeck coefficient and decrease in electrical conductivity. The power factor of Ca2.85Er0.15Co2O6 reached 10.66 μw/mK2 at 1073 K.