Effects of Cation Substitution on Electrical and Thermal Transport Properties of YCrO3 and LaCrO3

High-temperature electrical conductivity, Seebeck coefficient, and thermal conductivity measurements were used to study the effects of different cation substituents on electrical and thermal transport in YCrO₃ and LaCrO₃. The substitution of divalent Ca and Sr for Y and La, respectively, resulted in the formation of small polarons as charge carriers. The additional substitution of Mn for Cr resulted in the formation of a second charge carrier associated with the Mn. The electrical conductivity results were consistent with thermally activated transport by hopping of a temperature-independent carrier concentration. The activation energies were 0.20 and 0.12 eV for (Y,Ca)CrO₃ and (La,Sr)CrO₃, respectively, and increased to about 0.50 eV with the substitution of Mn for Cr. The Seebeck coefficient increased linearly with temperature and decreased with substituent concentration for both (Y,Ca)CrO₃ and (La,Sr)CrO₃. The substitution of Mn for Cr resulted in a Seebeck coefficient with a more complex dependence on temperature and substituent concentration. The thermal conductivity did not change significantly with either cation substitution or temperature.