Rapid synthesis of Ca2Co2O5 textured ceramics by coprecipitation method and spark plasma sintering

Ca2Co2O5 textured ceramics were rapidly prepared by a coprecipitation method and spark plasma sintering (SPS) using cobalt and calcium nitrates as starting materials and sodium hydroxide as precipitant. Single phase Ca2Co2O5 ceramics can be obtained by SPS at 800 °C for 5 min using the precursor powders calcined at 700-850° C for 2 h. It is critical to obtain stochiometric precursor by controlling the final pH 13.2 during the coprecipitation process. The SPS process is effective in obtaining single phase Ca2Co2O5 ceramics. The thermoelectric properties of the prepared sample were investigated from 100 to 700 °C. At 700 °C, the electrical resistivity, Seebeck coefficient, thermal conductivity and figure of merit of the sample are 9.30 × 10−5 Ω m, 178 μV/K, 1.55 W/mK and 0.21, respectively.