Effect of the Synthetic Method on the Structure and Electrical Conductivity of La0.5Ba0.5FeO3 as SOFC Cathode Materials

Abstract

The perovskite oxide La0.5Ba0.5FeO3 (with <rA>= 1.34 Aå) has been synthesised by ceramic and glycine-nitrate routes. The obtained compounds have been compared as cathode materials for intermediate temperature solid oxide fuel cells (SOFCs). These materials have been studied by inductively coupled plasma atomic emission spectroscopy, X-ray diffraction, scanning electron microscopy, four-probe conductivity measurements and electrochemical impedance spectroscopy. La0.5Ba0.5FeO3 samples prepared by the two methods have a mixture of rhombohedral (R-3c) and cubic (Pm-3m). The SEM images on bulk samples show that their morphology is clearly different depending on the preparation method. The electrical bulk conductivity of the samples has been measured in the 30-900ºC temperature range. The compound obtained by ceramic method show higher electrical conductivity than the one synthesised by glycine-nitrate route. Electrochemical impedance spectroscopy measurements have been realised at 700 and 800ºC. Impedance results indicate better electrochemical performance for the sample obtained by glycine-nitrate process.