Preparation and thermoelectric properties of Ca3Co2O6 ceramic bulk

Short-time solid-state reaction and spark plasma sintering method (SS-SPS) were combined to prepare single-phase polycrystalline Ca₃Co₂O₆ ceramic bulk, and effects of preparation condition and sintering technology were investigated in detail. Single-phase polycrystalline Ca₃Co₂O₆ powders with dendritic grains of about 1-3 μm and Ca₃Co₂O₆ ceramic bulk with grain size of about 2 μm were obtained respectively under 950°C for 2 h in the solid reaction process and spark plasma sintering under 900°C for 5 min. The ZT values of the polycrystalline product tend to increase sharply with increasing temperature and is 0.02 at 700°C, it is expected to possess high conversion efficiency and is considered to be a potential candidate for use as a thermoelectric materials at high temperatures.