Ab initio study on the adsorption mechanism of oxygen on Cr2AlC (0Â 0Â 0Â 1) surface

We performed an investigation of the early stage oxidation of the technologically relevant Cr2AlC (0 0 0 1) surface by ab initio calculations. In this work, the geometrical structure, bonding character, and electronic structure of the Cr2AlC (0 0 0 1) bare surface with or without single oxygen atom and molecular adsorption had been systematically investigated by DFT calculation. Four possible terminations Al-, Cr(C)-, C- and Cr(Al)-terminated Cr2AlC (0 0 0 1) surface are considered. The corresponding surface energies of the four configurations are compared, indicating that the Al- and Cr(C)-terminated surfaces are more stable than the other two cases C- and Cr(Al)-terminated surfaces. For the most stable case, Al-terminated Cr2AlC (0 0 0 1) surface, a detailed model describing the oxygen-surface interactions is developed by assessing the adsorption energetics of various adsorption mechanisms. Based on the evaluation of the energetics and the structural properties of the atomistic models generated, the results point to a consistent picture of the initial stage of the Cr2AlC (0 0 0 1) surface oxidation resembling that of (1 1 1) layer of pure Al FCC phase.