|About this Abstract
||Materials Science & Technology 2012
||International Symposium on Defects, Transport and Related Phenomena
||Surface Exchange in (La,Sr)MnO3 Films: Effects of Strain, Orientation, and Microstructure on Oxygen Reduction
||Lu Yan, Mioalei Yan, K. R. Balasubramaniam, Tim Fister, Dillon Fong, Jeffrey A. Eastman, Paul H. Fuoss, Paul A. Salvador
|On-Site Speaker (Planned)
||Paul A. Salvador
Transport of oxygen along or through surfaces is an essential component of many electrochemical devices. Yet, the surface properties of oxides in operational conditions are poorly understood. To build correlations between surface characteristics and properties for solid oxide fuel cell cathodes, thin flat films of (La,Sr)MnO<SUB>3±x</SUB> were deposited on perovskite and fluorite substrates and characterized structurally and electrically. Using synchrotron XRF, cation segregation was measured in operational SOFC conditions. Chemical surface exchange coefficients, <I>k<SUB>chem</SUB></I>, were measured using electrical conductivity relaxation as function of substrate, orientation, thickness, and epitaxy. Strain states and extended defect populations are demonstrated to influence strongly the magnitude and activation energy (E<SUB>A</SUB>) of <I>k<SUB>chem</SUB></I>. Importantly, the fastest exchange rates in SOFC conditions were for films under tensile strains. We demonstrate that significant departures from bulk or ceramic transport values are observed for the surfaces of epitaxial films and will discuss their implications for SOFC improvement.