Collect. Czech. Chem. Commun. 1994, 59, 2579-2582

On the Asymmetrical Role of Intrinsic Defects in the Complementary/Opposing Oxide Formation/Dissolution Reactions

Mohamed M. Hefny

Department of Chemistry, Faculty of Science, United Arab Emirates University, P.O. Box 17551, Al Ain, United Arab Emirates


Rates of chemical dissolution (r) of anodic oxide films on Sb, W, Al, Ti, Zr and Hf were studied as a function of the energy of defect formation (Ef) in the respective oxide. The value of r was estimated from capacitance measurements. The relation between ln r and Ef is linear. The average value of the symmetry factor (α) for the dissolution reaction is 0.12. The deviation of α from 0.5 indicates that intrinsic defects play an asymmetrical role; in the present case their constructive action is about 7 times their destructive action.