Ab initio atomistic thermodynamics study on the selective oxidation mechanism of the surfaces of intermetallic compounds

By combining ab initio density-functional theory and the thermodynamics calculations, we have constructed the surface phase diagrams (SPDs) for oxygen adsorption on the intermetallic compounds (IMCs) surfaces. Interestingly, from these SPDs, we can understand the selective oxidation behavior of IMCs surfaces easily and explains available experimental results successfully. Moreover, through a close examination of our results it can be found that two kinds of typical SPDs appear under O-rich conditions, i.e., a uniform single-phase SPD (type I) and a nonuniform double-phase SPD (type II) which correspond to the sustained complete selective oxidation and the nonsustained partial selective oxidation observed in the experiments. We believe that, using this general microscopic thermodynamics oxidation mechanism, one can easily judge and predict the oxidation behavior of arbitrary binary IMCs surfaces in the thermodynamics point of view.