Ab initio simulations of silver film adhesion on α-Al₂O₃ (0 0 0 1) and MgO (1 0 0) surfaces

The atomic and electronic structure of the Ag/MgO (1 0 0) and Ag/α-Al₂O₃(0 0 0 1) interfaces are calculated by means of the ab initio Hartree-Fock approach combined with a supercell model. The electronic density distribution and the interface binding energy/equilibrium distance for both interfaces are analyzed. For a complete (1:1) surface coverage of the MgO surface the energetically most favorable adsorption position for the Ag atom is above the O atom. For the Ag/α-Al₂O₃ interface the preferable adsorption positions for the Ag atom are over centers of either large equilateral oxygen triangles (in Al-substituted sites of Al-terminated corundum surface) or isosceles oxygen triangles (over O atoms of a first internal oxygen layer) in O-terminated corundum. This interface is less stable than Ag/MgO (1 0 0), due to a large mismatch between lattice constants of Ag (1 1 1) and α-Al₂O₃ (0 0 0 1) surfaces as well as the instability of Ag atoms on the Al-terminated corundum surface.