Thermoelectric Properties of Inhomogeneous Ceramics Based on the Layered Calcium Cobaltate

The effect of cationic composition and sintering conditions on the electrotransport and thermoelectric properties of Ca3CoxO (x = 3.8, 4.0, and 4.2) had been investigated. It had been found that increase of cobalt oxide content in the samples increase their electrical conductivity, creation of phase inhomogeneity improves their thermo-EMF coefficient, and sintering above temperature of peritectoid decomposition increase their apparent density, which, in the whole, improves thermoelectric properties of ceramics based on the layered calcium cobaltate Ca3Co4O . So, power factor values of phase inhomogeneous ceramics Ca3Co4.2O , sintered in air below and above temperature of peritectoid decomposition of Ca3Co4O , at 800℃ were equal 255 and 273 respectively, which was 2.1 and 2.4 times larger than for the Ca3Co4O . It had been also found that sintering of phase inhomogeneous ceramics both in oxidizing or reducing atmospheres resulted in improving of its functional properties. So, power factor values of Ca3Co3.8O (sintered in oxygen at 970℃) and Ca3Co4.2O (sintered in nitrogen at 920℃) at 800℃ were equal 422 and 378 respectively, which was 3.5 and 3.1 times larger than for the Ca3Co4O .