Immersion time and passive potential role on the passive and electrochemical response of tantalum in 0.1M HNO3 solution

In this study, the role of passive potential and immersion time in the responses of Ta, including electrochemical and passive, in HNO3 solution (0.1M) are investigated. Plots obtained from electrochemical impedance spectroscopy (EIS) reveal that the resistance of passive layers formed on the pure Ta against corrosion raises as the passive potential and immersion time increase. Moreover, Mott-Schottky (M-S) analysis is done to find the semiconducting properties of the given passive layers. The results indicate that passive potential and immersion time highly influence the concentration levels of donors through semiconductive behavior of pure Ta in the given solution is similar to that of n-type. The plots show that lower densities of donors in passive films deteriorate the resistance of the pure Ta against corrosion due to higher immersion time and passive potential. Moreover, the sensitivity of potentiality of flat bands to potentiality of passive films is another finding revealed by M-S plots.