Strain Effects on the Surface Chemistry of La[subscript 0.7]Sr[subscript 0.3]MnO[subscript 3]

Abstract

We report on the mechanistic effects of epitaxial strain on the surface chemistry, in particular the segregation of Sr cations on La0.7Sr0.3MnO3 (LSM) model dense thin films. Our results show that the LSM film surfaces are layered and exhibit strain-dependent nanoscale lateral structures. All surfaces examined here were Sr-rich. X-ray photoelectron spectroscopy shows a larger Sr segregation tendency for the tensile strained LSM films. This result is in good agreement with our first principles-based calculations, which predict lower Sr segregation energy on the tensile strained LSM surface. Our findings suggest the importance of lattice strain as a key parameter to tune the surface chemistry for facilitating oxygen reduction kinetics on transition metal perovskite cathode surfaces for solid oxide fuel cells.