Understanding the poisoning mechanisms of Si and Zr atoms on L12 Al3Ti (111) surface: A first-principles investigation

Abstract

In order to reveal the poisoning mechanism, the adsorption and diffusion of Si and Zr atoms on the L12 Al3Ti (111) surface have been investigated using first-principles calculations. Based on the results of adsorption energy and work function, the most favorable adsorption sites for Si and Zr atoms are H4 and T1 of L12 Al3Ti (111) surface, respectively. It is revealed from electron density differences, density of states and Mulliken population that the Ti–Si covalent bonds in Si@Al3Ti(111) system the hybridization of Si 3p and Ti 3d orbitals while the Ti–Zr ionic bond in Zr@Al3Ti(111) system is come from the contribution of Ti 3d and Zr 4d orbitals. By calculating formation energy, it is found that the Si and Zr atoms prefer to incorporate the Al site of the first layer and Ti site of the second layer of L12 Al3Ti (111) surface, respectively. The energy barriers of Si and Zr atoms diffusion on or into L12 Al3Ti (111) surface are also evaluated.