Kinetics of the initial stage of electrolytic deposition of metals III. Galvanostatic conditions

The kinetics of the initial stage of the electrolytic deposition of a thin metal film onto an inert cathode are considered for the case when the electric current flowing through the electrolytic cell is held constant with time. In studying the process the Gibbs-Thomson effect is taken into account and the cases of pure ohmic control, volume diffusion control and phase boundary transition control are examined separately. Expressions are derived for the radius of a single crystallite, the mean crystallite radius and the overvoltage as functions of time and current strength for each of the above types of growth control. Formulae are also obtained for the maximum overvoltage, the time taken to reach it and the maximum number of crystallites on the cathode as functions of the electric current. The analysis shows that the decrease in the maximum number of crystallites with decreasing current approximately obeys a power law and that there exists a critical value of the electric current, different for the different types of control, below which only one crystallite forms and grows on the cathode.