Influence of Oxygen Activity-Dependent Interfacial Non-Stoichiometry on Diffusion at Metal-Oxide Interfaces

摘要

Interfacial chemistry at (ternary) metal-oxide interfaces depends on the oxygen chemical potential. It changes within the coexistence range of metal and oxide, from interfacial oxygen excess at high oxygen chemical potential to local oxygen depletion at low oxygen chemical potential. Modifications of the local interfacial chemistry compared to bulk chemistry are stabilized by charge transfer across the interface between metal and oxide and give rise to the formation of a space charge layer in the oxide. This space charge layer is characterized by a relative depletion of positive charge carriers in case of oxygen excess and by a relative depletion of negative charge carriers in case of oxygen deficiency. As a consequence, diffusion along and across the interface strongly depend on the oxygen chemical potential and are expected to show anomalies related to the modified defect concentrations.