Potential‐Induced Impedance Variations in Barrier‐Type Aluminum Oxide Films in Aqueous Sodium Sulfate

Negligible changes occur in the dielectric properties of barrier- layer anodic aluminum oxide films exposed (50 hr) to neutral aqueous sodium sulfate at the open-circuit potential and -725 mV vs SCE, indicating little film-environment interaction. Transmission electron micrographs of films exposed f...

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Bibliographic Details
Published in:Journal of the Electrochemical Society 1976-06, Vol.123 (6), p.864-871
Main Authors: Libsch, T. A., Devereux, O. F.
Format: Article
Language:English
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Summary:Negligible changes occur in the dielectric properties of barrier- layer anodic aluminum oxide films exposed (50 hr) to neutral aqueous sodium sulfate at the open-circuit potential and -725 mV vs SCE, indicating little film-environment interaction. Transmission electron micrographs of films exposed for this time to the same chemical environment at 10 and 20 V show the presence of a deposit on the surface of thinned anodic oxide; this deposit is presumably hydrated aluminum oxide. Significant changes observed in the dielectric properties of films tested at these two potentials have been analyzed by means of an a.c. impedance model yielding dielectric constant and resistivity values and thickness-time profiles for the anodic and hydrated layers. 20 ref.--AA.
ISSN:0013-4651
1945-7111
DOI:10.1149/1.2132958