Oxygen incorporation into Fe-doped SrTiO3: Mechanistic interpretation of the surface reaction

Abstract

The surface part of the oxygen incorporation reaction into the model material Fe-doped SrTiO₃ is investigated by in situ optical spectroscopy. Experiments close to and far from equilibrium (small and large pO₂ changes) and the effect of UV irradiation on the reaction rate allow us to draw the following conclusions with respect to the kinetic processes at the surface: (i) molecular oxygen species participate in or before the rate determining step (RDS), and (ii) a single conduction band electron participates in or before the RDS of the incorporation reaction even though the bulk is p-type conducting. Probable reaction mechanisms comprising chemisorption, charge transfer, dissociation and oxygen ion transfer steps are discussed.