KINETICS OF SURFACE SEGREGATION DURING LINEAR PROGRAMMED HEATING

An analysis of the experimentally investigated kinetics of surface segregation can be used to obtain information on the diffusion properties of the system near the surface. A promising way for an efficient experimental analysis of the temperature dependence of the effective diffusion coefficients is the investigation of surface segregation with linearly programmed heating (LPH), in which the temperature is increased linearly with time during the experiment. Model calculations of the segregation kinetics during LPH have been performed on the basis of a modified KTBIM (kinetic tight-binding Isin model) for dilute binary and ternary systems to investigate the general segregation kinetics and the applicability of this method in real systems. The results allow one to determine the conditions under which experimental data can be used to obtain the Arrhenius parameters of the effective diffusion coefficients of the segregating elements in real systems. Additional model calculations performed to describe the segregation kinetics of N and S in polycrystalline Fe and Sn at the Cu(111) surface show excellent agreement with experimental results and demonstrate the sensitivity of this model.