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An axial dispersion model of competing ion etching and mixing of binary solids
Author(s) -
Elias Raul J.,
Barteau Mark A.
Publication year - 1993
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690390210
Subject(s) - ion , penetration (warfare) , dispersion (optics) , mixing (physics) , ion exchange , péclet number , solid solution , chemistry , materials science , discontinuity (linguistics) , solid surface , sputtering , plug flow , diffusion , mechanics , thermodynamics , chemical physics , optics , nanotechnology , thin film , physics , metallurgy , mathematical analysis , mathematics , organic chemistry , operations research , quantum mechanics , engineering
Ion bombardment of solid surfaces produces a number of changes in the nearsurface region. The surface is etched by ejection of material by momentum exchange. The surface concentrations of the components of a multicomponent solid, such as an alloy, are altered by preferential sputtering. Finally, the incident ions penetrate a distance into the solid, producing a damaged region referred to as the “altered layer” in which diffusion is enhanced relative to that in the unaltered bulk. Previous models have not explicitly accounted for the ion penetration depth and the discontinuity of solid diffusivities at this boundary. We demonstrate that this problem is directly analogous to that of a plug‐flow reactor with axial dispersion, and solve for steady‐state and transient concentration profiles in a binary solid, taking into account the different values of the “Peclet number” appropriate for the two regions, the altered layer and the unaltered bulk of the solid.