Initial oxidation kinetics and energetics of Cu0.5Au0.5 (0 0 1) film investigated by in situ ultrahigh vacuum transmission electron microscopy

The initial oxidation behavior of Cu0.5Au0.5 (0 0 1) thin film was investigated by in situ ultrahigh vacuum transmission electron microscopy to model nano-oxidation of alloys with one active component and one noble component. The formation of irregular-shaped octahedron Cu2O islands with cube-on-cube crystallographic orientation to the substrate film was observed at all temperature studied. The energetics of Cu2O nucleation for Cu and Cu0.5Au0.5 oxidation was compared. Cu0.5Au0.5 oxidation has lower nucleation activation energy due to the reduced mismatch strain between Cu2O and Cu0.5Au0.5 films. On the other hand, the reaction kinetics for Cu0.5Au0.5 alloy oxidation is slower due to the higher diffusion activation energy of Cu.