Film models instantaneous nucleation

The instantaneous nucleation-growth-precipitation model [39] assumes that the film is formed directly on the substrate, without previous dissolution however, it was observed that active dissolution of the metal occurs. Therefore, Equations 8.11 through 8.13 were examined and rewritten considering metal dissolution, that is, terms corresponding to dissolution were added to the mathematical expressions ... 

The number of sites participating in the formation of Sn02 is N0 = 3.0 x 1010 cm-2. This value is similar to those usually found for active sites in the case of metals [67]. As the diagnostic criteria for the instantaneous nucleation-growth-overlap model was fulfilled and physicochemical data obtained for No is physically plausible, we may conclude that instant nucleation with lateral growth of the film occurs. Taking into account that the atomic density of the substrate is of the order of 1015 cm2 [67], we conclude that the density of the active sites on the surface can severely limit the nucleation process. 

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