Formation of Co-Mn Composite Oxide Films from Saturated Solution

Abstract

Co-Mn Conposite oxide films were formed on stainless steel electrodes by polarizing them slightly cathodically in a dilute aqueous solution containing Co^2÷ and MnO₄^- ions. The solutions were supersaturated with sparingly soluble compounds, Co₂O₃ and MnO₂, which were produced as a result of the redox reaction between Co²⁺ and MnO₄^- ions. Supersaturation was kept during the film formation. The [Mn] / [Co] ratio of the films varied with the concentrations of Co²⁺ and MnO₄^- ions in the solution, the elapsed time from solution preparation, and the electrode potential of stainless steel. This method is applicable to the film formation of sparingly soluble compounds on conductive materials.