ELECTRICAL-CONDUCTIVITY AND SEEBECK COEFFICIENT OF (LA, CA) (CR, CO)O3

Electrical conductivity and Seebeck coefficients of (La, Ca) (Cr, Co) O3 were measured as a function of temperature. The electrical conductivity as measured in air from 100 to 1100-degrees-C increased with increasing Co and Ca content. The Seebeck coefficients were positive, indicating p-type conductivity. The substitution of Co for Cr significantly decreased the Seebeck coefficients, indicating that the substitution resulted in an increase in site occupancy, associated with the Co. The additional Ca substitution for La resulted in further decrease in the Seebeck coefficients, then exhibited a temperature-independent behaviour, indicating that the carrier mobility, rather than carrier concentration, was thermally activated. The activation energies were 0.18 and 0.25 eV for LaCrO3 and LaCoO3, respectively, and increased to about 0.50 eV with substitution of 10 mol % Co for Cr and then linearly decreased as Co content increased.