Relative content of the Cr4+ ion and electrical conductivity of La0.75Ca0.25Cr0.75Fe0.25O3

La0.75Ca0.25Cr0.75Fe0.25O3 is synthesized by a wet chemical method and the electric conductivity of the compound in air is measured over a temperature range from 296 to 1083 K. Arrhenius plot for La0.75Ca0.25Cr0.75Fe0.25O3 is composed of two Line segments and the discontinuity is at 532 K. The appro ximate calculation for the temperature dependence of the electrical conduct ivity of the compound has been performed in consideration of the thermodyna mic equilibrium between the Cr3+ and Cr4+ ions in the compound. The electri cal conductivity of lanthanum chromite is directly proportional to the rela tive content of the Cr4+ ion in the compound and the relative content of th e Cr4+ ion ib La0.75Ca0.25Cr0.75Fe0.25O3 increases with temperature. The ac tivation energy and the electron hopping frequency map have more significan t effect on the electric conductivity of the compound. The occurrence of th e oxygen deficiency in the doping lanthanum chromite can be explained by th e calculated results. (C) 2001 Elsevier Science B.V. All rights reserved.