Electronic Structure Measurements of Heteroepitaxial Solid Oxide Fuel Cell Cathode Thin Films

Abstract

Synchrotron based total reflection x-ray fluorescence (TXRF) and hard x-ray photoelectron spectroscopy (HAXPES) technique have been utilized to measure the compositional changes and evolution of surface chemistry of strontium doped lanthanum cobalt iron oxide (LSCF) annealed at 800 °C, as a function of strontium dopant concentration and gas composition. TXRF is a useful way to depth-profile the surface composition of material at elevated temperatures in real time. The capability of HAXPES to overcome surface contamination issues helps better understand the segregation phenomena. This study demonstrates that the formation of Sr carbonate results in enhanced kinetics of Sr surface segregation in LSCF thin films with presence of CO2 when annealing at 800 °C and lowering the Sr dopant concentration results in a decrease Sr surface segregation.