Role of segregating impurities in grain-boundary diffusion.

The impact of segregating impurities on grain-boundary diffusion is investigated using a kinetic Monte Carlo simulation of boundary transport on a lattice that is appropriate for both slab and pipe geometries. More specifically, the grain-boundary diffusivity is determined as a function of impurity concentration using an analog of the experimental sectioning method. The retardation of diffusion that results from segregation is interpreted in terms of site-blocking models that reflect the local free volume available to a diffusing tracer. Finally, the results of this investigation are interpreted in the context of experimental determinations of grain-boundary diffusivity in doped ceramic oxides.