Effect of Different Preparation Processes on Thermoelectric Properties of Ca_3Co_4O_9

The Ca3Co4O9 samples are synthesized by solid state reaction and citrate acid sol-gel method.The phase distributions,microstructure and thermoelectric properties are compared for the samples prepared by the two methods.Compared with solid state reaction method,sol-gel method could prepare Ca3Co4O9 sample which has higher diffraction peak,finer grain size,evenly distributed grains and the material density is enhanced.The results show that the electrical resistivity of the sample synthesized by sol-gel method decreases and the Seebeck coefficient increases slightly,so the thermoelectric properties are enhanced.