An electrochemical impedance analysis of passive films on nickel(111) in phosphate buffer solutions

✍ Scribed by Digby D. Macdonald; Stuart I. Smedley

• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 811 KB
• Volume: 35
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(90)87104-a

✦ Synopsis

A&r&-Electrochemical

impedance data for single crystal Ni( 111) in phosphate buffer solutions of pH 9, 10, and 11 and at potentials spanning the passive range (0.1-0.5 V/see) are interpreted in terms of a point defect model for the passive film in which the kinetics of generation and annihilation of vacancies at the metal/film and film/solution interfaces are taken into account. The best fit of the model to the experimental data was obtained by assuming that cation vacancies are mobile in the film. A single set of kinetic and transport parameters, a constant electric field strength, and a potential dependent double layer capacitance were sutIicient to reproduce the experimental impedance at frequencies from 10 kHz to 1 mHz, at pH values from 9 to 11, and at applied voltages of 0.1 and 0.5 V/SW.