Apparent surface rate constants in diffusion problems - Flux constriction effects

The impact of surface inhomogeneities on diffusion kinetics in solids is in vestigated by assuming that the exchange of the diffusing species takes pla ce at active spots or stripes only. Finite element simulations are analyzed on the basis of analytical approximations. Such lateral inhomogeneities le ad to an apparent surface rate constant even in cases in which the local su rface kinetics at the active spots is infinitely first. The influence of ge ometric parameters (e.g., size and distance between the active sites) as we ll as control parameters such as the temperature on the apparent surface ra te constant is investigated. (C) 2000 The Electrochemical Society. All righ ts reserved.