Current transients caused by potential jumps applied to passivating films on nickel

Positive and negative potential steps between values well within the passivation range are applied to nickel in borate buffer solution passivated for various times and at various temperatures. The transient cathodic current following a negative potential jump leads to the deduction of the potential dependence of the mean valence of nickel ions in the passivating films. The identity of the magnitudes of charge involved in the up-jumps and down-jumps of potential lead to the inference of reversible behavior at the film-electrolyte interface.