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International Journal of Electrochemistry
Volume 2011, Article ID 968512, 6 pages
http://dx.doi.org/10.4061/2011/968512
Research Article

Diffusivity of Point Defects in the Passive Film on Stainless Steel

Faculty of Engineering, Bu-Ali Sina University, Hamedan 65178-38695, Iran

Received 25 October 2010; Revised 2 December 2010; Accepted 14 December 2010

Academic Editor: Sergio Ferro

Copyright © 2011 A. Fattah-alhosseini et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The semiconductor properties of passive films formed on AISI 316 stainless steel in sulfuric acid solution were studied by employing Mott-Schottky analysis in conjunction with the point defect model. The donor density of the passive films, which can be estimated by the Mott-Schottky plots, changes depending on the film formation potentials. Based on the Mott-Schottky analysis, an exponential relationship between donor density and the film formation potentials of the passive films was developed. The results showed that the donor densities evaluated from Mott-Schottky plots are in the range 2-3 × 1021 cm−3 and decreased with the film formation potential. By assuming that the donors are oxygen ion vacancies and/or cation interstitials, the diffusion coefficient of the donors, ( 𝐷 𝑂 ), is calculated to be approximately 3.12 × 10−16 cm2/s.