Oxygen exchange kinetics in perovskite oxides: Effects of elastic strain, dislocations, and surfaces

Interfaces between dissimilar oxides are attracting significant interest for their potential role in accelerating charge transport and surface reaction kinetics. If well understood and controlled, they can provide a new way to enable high-performance solid-oxide fuel cells, separation membranes as well as fast switching memristive devices. For example, recent studies have demonstrated that cobaltite hetero-interfaces exhibit orders of magnitude faster oxygen reduction kinetics compared with either single phase. The interfacial strain fields and electronic interactions between the two phases as well as the effect of these interactions on the surface chemistry are the likely mediators behind such an unprecedented enhancement. The underlying mechanisms must be understood quantitatively, so that we can go beyond isolated and empirically found interface or surface structures to rationally designing dissimilar oxide interfaces with superior properties. In this talk, I will present our findings on how elastic strains, dislocations, and surface chemistry affect the defect chemistry and the charge transport/transfer kinetics, by using atomistic computations and model experiments using thin films. These recent results are encouraging for an improved understanding of oxide hetero-interfaces and surfaces at elevated temperatures, and could enable the discovery of new interfaces with fast oxygen transport and oxygen reduction kinetics.