Surface Gibbs free energy analyses of Sr segregation in lanthanum strontium iron oxide

Sr surface segregation in mixed-cation oxides often causes degradation of chemical or electrochemical performance. In this work, the thermodynamic driving force for Sr segregation is investigated to explain the Sr segregation behavior in La0.5Sr0.5FeO3 (LSF). Specifically, Density Functional Theory is used to calculate the surface Gibbs free energy of various surface terminations of cubic (100) LSF as a function of chemical potential and temperature. SrO-terminated surfaces are predicted to be dominant, promoting Sr segregation at high temperatures and low oxygen partial pressure.

Automated summary

Sr surface segregation is commonly observed in mixed-cation oxides, leading to degradation of chemical or electrochemical performance. In this study, the thermodynamic driving force for Sr segregation in La0.5Sr0.5FeO3 (LSF) is investigated. Density Functional Theory calculations show that SrO-terminated surfaces dominate, promoting Sr segregation at high temperatures and low oxygen partial pressure.