Synthesis and Characterization of Ca₃Co₄O₉ Thermoelectric Ceramics using the Slurry Sintering Method

Abstract

Ca 3 Co 4 O 9 samples were made by the sintering method using the slurry consisted of Ca 3 Co 4 O 9 powder and Ca 3 Co 4 (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 Ca 3 Co 4 O 9 powder to 13 or 18 wt.% Ca 3 Co 4 (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 Ca 3 Co 4 O 9 samples could be controlled by the slurry sintering method. The electric conductivity ( ), Seebeck coefficient (S), and power factor (PF) of samples prepared by slurry sintering method at room temperature are 53 S/cm, 118 V/K and 73.8 W/m ⋅ K 2 , respectively. The power factor (PF) at 600 • C was 173 W/m ⋅ K 2 . K E Y W O R D SCa 3 Co 4 O 9 , oxide thermoelectric material, slurry sintering method, thermoelectric properties Electron Comm Jpn. 2019;102:3-9.