Simulation of spreading of precursing Ag films on Ni(1 0 0)

The diffusion of Ag away from partially wetting Ag particles on Ni(1 0 0) substrates, to form so-called precursing films, has been studied by means of molecular dynamics simulations. The maximum thickness of the precursing film is one Ag monolayer at the edge of the particle. An analysis of the time dependence of the concentration gradient in the film shows that the kinetics of film growth may be described by diffusional processes, with a diffusivity that is significantly coverage dependent. No ordered surface phases, or evidence of surface alloying of the Ag with the Ni substrate have been found. It is also shown that the coverage dependence of diffusivity can be interpreted only qualitatively in terms of simple diffusive processes in the limits of high and low coverage.