The Field-Dependence of the Dielectric Constant during the Anodic Oxidation of Tantalum, Niobium, and Tungsten
Year: 1972
Type: article
Abstract: In situ ellipsometric measurements on the galvanostatic oxidation of tantalum, niobium, and tungsten show that both the refractive index and the thickness of the oxide change suddenly on changing the current applied to the film. For all three metals the thickness was found to increase linearly with the electric field, whereas both the refractive index and low frequency (1000 Hz) dielectric constant were found to decrease linearly with increasing field. The magnitudes of the changes in dielectric constant and refractive index that were detected experimentally, when compared with theoretical predictions using standard dielectric theory and the observed change in thickness, indicate that these changes are due to the variation in the density of the film with the applied field. The inclusion of the linear dependence of the dielectric constant on field into an effective field model of the ionic conduction process is shown to be a possible explanation of the curvature in the plot of ln( i ) vs. E for the anodic oxidation process.
DOI: 10.1149/1.2404226
Authors: J. L Ord, M. A. Hopper, W. P. Wang
Institution: University of Waterloo
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2058029611