Spectroscopic ellipsometry of electrochemical precipitation and oxidation of nickel hydroxide films

In situ spectroscopic ellipsometry was used to investigate the electrochemical precipitation of nickel hydroxide films. By use of optical models for inhomogeneous films it was found that a specific precipitation current density produced the most compact and homogeneous film structures. The density of nickel hydroxide films was derived to be 1.25-1.50 g/cm³. The redox behavior of precipitated nickel hydroxide films was studied with an effective-medium optical model. Incomplete conversion to nickel oxyhydroxide and a reduction in film thickness were found during the oxidation cycle.