Kinetic mechanism of anodic oxidation of tantalum in nitrate melts①
(1. Department of Physical Chemistry, University of Science and Technology Beijing,
Beijing 100083, P.R.China;
2. Institute of Applied Physics, Jiangxi Academy of Sciences, Nanchang 330029, P.R.China)
Beijing 100083, P.R.China;
2. Institute of Applied Physics, Jiangxi Academy of Sciences, Nanchang 330029, P.R.China)
Abstract: The data of anodic oxidation of tantalum in high temperature nitrate melts were regressed according to 41 kinds of probable kinetic mechanism. The results show that the process follows the parabolic lawα2=kt, which means that the process of anodic oxidation of tantalum is limited by the movement of positive vacancies of tantalum ions. The voltage has an effect on the rate constant in prior period, which implies that the electromigration exists at the beginning of film growth. The breakdown of films exists in whole process. The films obtained are composed of orthorhombicβ-Ta2O5 and TaOy.
Key words: kinetics; anodic oxidation; tantalum