Effect of chromium doping on structural development and electrical properties of LaNiO3 perovskites

Abstract

Perovskite-type oxides (ABO₃) are potential alternatives as electrode materials for IT-SOFC. Their properties of electronic conduction, catalytic activity, and stability in oxidative and reductive atmospheres arouse this interest. Due to their electronic conduction properties, both LaNiO₃ perovskites, commonly used as a cathode, and LaCrO₃ perovskites, commonly used as interconnectors, can also be developed to be used as an anode. Thus, this work describes the results of experiments carried out on Cr-doped LaNiO₃ compositions aiming at their use as fuel cell anodes. The compositions of LaNi_1 − xCr_xO₃ (0 ≤ x ≤ 0.7) were synthesized by a modified Pechini method, and the effects of replacing Ni with Cr in LaNiO₃, mainly perovskite phase formation and structural stability, beyond microstructure and electrical properties were analyzed. Phases with a perovskite-like structure were obtained via calcination at 900 °C. For the sintered samples, it was observed that an increase in the amount of Cr led to an increase in porosity. The compositions with x = 0.7 and x = 0.5 sintered at 1300 and 1400 °C remained single-phase after sintering, while the composition x = 0.3 sintered at 1500 °C and the composition x = 0.0 sintered at 1250 °C decomposed into secondary phases. Concerning electrical properties, the activation energy values obtained were consistent with electronic conductivity, 0.03 eV, indicating p-type conduction in an oxidizing atmosphere.