Ba-substituted LSCM anodes for solid oxide fuel cells

Three perovskites with the general formula La0.75BaxSr0.25-xCr0.5Mn0.5O3 (x = 0, 010 and 0.25) have been synthesized. For all materials, the symmetry is rhombohedral (space group R-3c). On the electrical point of view, a p-type semiconducting behaviour was evidenced in the series. The addition of barium yields an increase in total conductivity in argon from 18 S cm(-1) for La0.25Sr0.25Cr0.5Mn0.5O3 to 26 S cm(-1) for La0.75Ba0.25Cr0.5Mn0.5O3 at 900 degrees C. However, in H-2-3% H2O, the total conductivity decreases for all compositions and it decreases with barium substitution (0.9 S cm(-1) for La0.75Sr0.25Cr0.5Mn0.5O3 and 0.5 S cm(-1) for La0.75Ba0.25Cr0.5Mn0.5O3 at 900 degrees C). Steady state and impedance spectroscopy measurements were performed on dense pin-shaped electrodes (x = 0 and 0.25) in H-2-3% H2O between 800 and 900 degrees C. For x = 0.25, electrochemical performances are interesting for an applicability as an SOFC anode. Origins of individual contributions to the electrode reaction mechanism are discussed. (C) 2012 Elsevier B.V. All rights reserved.