Preparation and thermoelectric properties of Ca/sub 3/Co/sub 2/O/sub 6/ ceramic bulk

Short-time solid-state reaction and spark plasma sintering method (SS-SPS) were combined to prepare single-phase polycrystalline Ca/sub 3/Co/sub 2/O/sub 6/ ceramic bulk, and effects of preparation condition and sintering technology were investigated in detail. Single-phase polycrystalline Ca/sub 3/Co/sub 2/O/sub 6/ powders with dendritic grains of about 1-3 /spl mu/m and Ca/sub 3/Co/sub 2/O/sub 6/ ceramic bulk with grain size of about 2 /spl mu/m were obtained respectively under 950/spl deg/C for 2 h in the solid reaction process and spark plasma sintering under 900/spl deg/C for 5 min. The ZT values of the polycrystalline product tend to increase sharply with increasing temperature and is 0.02 at 700/spl deg/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.