ANODIC DEFECT FORMATION, NONSTOICHIOMETRY, AND PHASE-TRANSFORMATIONS IN OXIDE-FILMS ON NICKEL IN ACID-SOLUTION

Anodic defect formation in oxide films on nickel in acid solution is s tudied using photoelectric recombination technique in conjunction with resistometry and potentiometry. Anodic nickel dissolution in acid sol ution is shown to proceed with the participation of a surface oxide wh ose nonstoichiometry and defect structure vary with the potential. Ano dic boundaries of the stability region for oxide phases on nickel are determined with respect to both an oxygen and a metal excess. Potentia ls of the oxide stability boundaries are demonstrated to correspond wi th the passivation potentials for nickel. Nonstoichiometry vs. potenti al diagrams are obtained, which allow the nature of prevailing nonstoi chiometric defects and their concentration at different electrode pote ntials to be evaluated.