Synthesis and characterization of Ca3Co4O9 thermoelectric ceramics using the slurry sintering method

Abstract

Ca3Co4O9 samples were made by the sintering method using the slurry consisted of Ca3Co4O9 powder and Ca3Co4(OH)18 hydroxide in binder solution. The preparation conditions for making the crack free samples were examined, and we found that using the slurry having a mixing ratio of Ca3Co4O9 powder to 13 or 18 wt.% Ca3Co4(OH)18 hydroxide in binder solution of 10:1.5, samples with a few crack could be prepared. From SEM observation, it was found that the void density in Ca3Co4O9 samples could be controlled by the slurry sintering method. The electric conductivity (σ), Seebeck coefficient (S), and power factor (PF) of samples prepared by slurry sintering method at room temperature are 53 S/cm, 118 μV/K and 73.8 μW/m · K2, respectively. The power factor (PF) at 600°C was 173 μW/m · K2.