Date of Award


Degree Type


Degree Name

Doctor of Philosophy


This thesis is concerned with an experimental and a theoretical study of the effects of bulk diffusion on the electrolytic nucleation and growth of silver deposits on tin oxide-coated glass and on glassy carbon. The existing nucleation and growth theory is extended to cover cases where the electrode concentration is a function of time. The manner in which the electrode concentration varies with time depends on the transport of metal ions through the bulk of the solution. The time dependent concentration functions are coupled with solutions of the differential equations that describe transport in solution.;Finite difference calculations are done on single isolated growth sites, as well as on growth sites arranged in square grids. These square grids of sites are used to show that when the site density is greater than 10('8) sites cm('-2) uniform concentration across the face of the electrode can be assumed. Once the assumption of uniform concentration is made, it is possible to calculate current-time transients without resorting to finite differences. The non-linear integral equation is used to numerically solve for the electric current and the electrode concentration of metal ions as functions of time. This technique is shown to be very versatile and is used to calculate current transients where such factors as site overlap and electrode resistance are important. In the simplest case where metal deposition (no back-reaction) without site overlap or significant electrode resistance is occurring, an exact solution for the current-time transient and the metal ion concentration at the electrode is found.;The integral equation solutions for the current transients are then fitted, via a non-linear least-squares technique, to current transients obtained from the poteniostatic deposition of silver on tin oxide-coated glass electrodes. The parameters of these least-squares fits are then used to calculate the electrode symmetry factor for silver reduction and the diffusion coefficient for silver ion in 1 mol L('-1) KNO(,3). Both values compare well with literature values. This is the first quantitative model for the effect of bulk diffusion on the nucleation and growth kinetics of electrolytic silver deposits on semiconductors.



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