KINETICS OF THE ANODIC-OXIDATION OF BISMUTH IN GLYCOL BORATE ELECTROLYTE - A SPACE-CHARGE APPROACH

The kinetics of anodization of bismuth in glycol-borate electrolytes is investigated using galvanostatic and potentiostatic methods. A model based on the ionic space charge concepts is proposed. The main assumption of the model is that positive charge carriers are responsible for film growth, and negative charge carriers form a background space charge which enhances the transport of positive carriers. Using this framework an equation for the potential vs quantity of charge dependence is derived and fitted to experimental data for galvanostatic oxidation. During the potentiostatic stage of anodization, the negative space charge dissipates and a homogeneous field is established in the film.