Thermoelectric Ceramics Based on the Layered Cobaltates of Bismuth and Alkaline-Earth Metals

Using solid-state reactions method the ceramic samples of (Bi,Pb) 2 Ba 2 (Co,M) 2 O y , (Bi,Pb) 2 Sr 2 (Co,M) 1.8 O y , and (Bi,Pb) 2 Ca 2 (Co,M) 1.7 O y (M = Mn, Zn) solid solutions had been prepared, their lattice constants had been determined and their thermal expansion, electrical conductivity and thermo-EMF had been measured, and their power factor had been calculated. Effect of the bismuth substitution by lead and cobalt substitution by manganese and zinc in the layered cobaltates of bismuth and alkaline-earth metals (AEM) on the crystal structure and physicochemical and functional properties of their derivatives was analyzed. It was found that cobaltates studied are p-type conductors, which linear thermal expansion coefficient (LTEC) values varied within (9.68-13.2)•10 -6 K -1 . Power factor values for the samples studied unmonotonously changed when temperature increased and at 1000 K were maximal for Bi 2 Ba 2 Co 2 O y , Bi 2 Sr 2 Co 1.7 Mn 0.1 O y , and Bi 2 Ca 2 Co 1.7 O y compounds - 12.1, 10.1, and 10.6μW/(m•K 2 ) respectively.