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

Abstract

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.