Molten salt synthesis and thermoelectric properties of Ca2Co2O5

A molten salt method was applied to synthesize Ca2Co2O5 powder by using Co3O4 and CaCO3 as raw materials and CaCO3-CaCl2 as eutectic salt. The formation process and molten salt mechanism of Ca2Co2O5 were investigated by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that sheet-like particles can be obtained at 963 K. Moreover, the electrical conductivity and the Seebeck coefficient of the specimen were measured from 323 to 963 K. The properties increased with increasing temperature and the highest value of power factor (2.0 x 10(-4) W m(-1) K-2) was obtained at 963 K, which indicates that molten salt synthesis is a promising method to prepare high thermoelectric performance material. (C) 2009 Elsevier B.V. All rights reserved.