Influence of Ba2+ substitution on Structural, Dielectric, Thermal and Electrical behavior of La1-xBaxCo0.50 Fe0.50O3 {0.10≤ x≤ 0.40} Cathode for SOFC

Abstract

La1-xBaxCo0.50Fe0.50 O3; {0.10≤ x≤ 0.40} perovskite ceramics is prepared by solid-state reaction method. The as-prepared samples are characterized by X-ray diffraction, scanning electron microscope, dilatometer, thermogravimetric analyzer (TGA) and impedance spectrometer. Samples are well crystallized in single phase and the crystal structure is found to be rhombohedral. Grains are non uniform and size of the grains is decreasing with Ba substitution. Density of the material is measured by Archimedes principle. At high temperature, reduction of cobalt and iron takes place. Thermal expansion coefficients for x = 0.10 and 0.40 at 200 °C - 800 °C temperature are 13.4 ×10-6 °C- 1 and 11.8×10-6 °C-1 respectively. Dielectric analysis shows that as prepared samples obey non-Debye relaxation behavior. The maximum value of the conductivity is 136.32 Scm-1 for x = 0.10 and 168.60 Scm-1 for x = 0.40. Activation energies are found to be 0.20 eV and 0.17 eV for x = 0.10 and 0.40 respectively. Electrical conductivity is greater than 100 Scm-1 which suggests it to be a suitable cathode material for SOFCs.