Vacancy assisted SrO formation on La0.8Sr0.2Co0.2Fe0.8O3−δ surfaces—A synchrotron photoemission study

We present a systematic synchrotron radiation photoemission spectroscopy study of the interaction of O2 with defective La0.8Sr0.2Co0.2Fe0.8O3−δ(100) surfaces at low temperatures. First, the surface chemical evolution during low energy Ar+ ion sputtering is investigated and is found to create oxygen vacancies. Subsequently, the interaction of the O2 molecules with La0.8Sr0.2Co0.2Fe0.8O3−δ(100) surface is observed to create an insulating phase. We performed a detailed core-level peak-fitting analysis to identify the chemical nature of this phase and to probe the role of vacancies in the formation of this phase. [Display omitted] •The interaction of oxygen molecules with defective La0.8Sr0.2Fe0.2Co0.8O3−δ (LSCF) is studied.•Oxygen vacancy creation in LSCF using low energy Ar+ ion sputtering•Formation of insulating SrO phase on LSCF surface at 150°C•Dependence of SrO formation on oxygen vacancy concentration