Atomistic Simulations of Al(100) and Al(111) Surface Oxidation: Chemical and Topological Aspects of the Oxide Structure

The chemical and topological aspects of short- and medium-range atomic ordering on oxidized Al(100) and Al(111) surfaces have been studied by employing reactive force field-based molecular dynamics (ReaxFF-MD) simulations as a function of O2 gas density at 300 K. We found two oxide film growth regimes, compatible with experimental and recent modeling data. Trend of changes in oxide film thickness with increasing oxygen gas density agrees with available literature data, while slightly thicker oxide film forms on the Al(100) substrate. Chemical descriptors of short- and medium-range correlation manifest difference in atom environment between two ultrathin oxide films as [3,4]Al and [2,3]O-coordinated species dominate. In turn, a highly liquid-like structure of ultrathin oxide film develops on the Al(100) surface compared to an amorphous nature of the Al(111) oxide film with slightly lower thickness. Three-dimensional analysis of oxide structures reveals a medium-range atomic order formed by the arrangement ...