Synthesis and Properties of Ceramics Based on a Layered Bismuth Calcium Cobaltite

Bi2Ca2CoxOy (x = 0.5, 1.7, 2.8) ceramics have been prepared by solid-state reactions and their thermophysical, electrical-transport, and thermoelectric (functional) properties have been studied. The results demonstrate that increasing the cobalt oxide concentration in the ceramics leads to an increase in their thermal conductivity, electrical conductivity, and thermal diffusivity and a reduction in their apparent density. The largest Seebeck coefficient is offered by a single-phase ceramic with the composition Bi2Ca2Co1.7Oy, which in addition has the highest power factor (P-300 = 26.0 mu W/(m K-2)) and thermoelectric figure of merit (ZT(1000) = 0.019) and the smallest linear thermal expansion coefficient (alpha = 9.72 x 10(-6 )K(-1)).