Dielektrisches verhalten von Ta2O5-Schichten im elektrolyten

Abstract

Deviations from the normal course of the capacitance and of the equivalent series resistance as a function of the frequency in anodized tantalum measured in dilute aqueous electrolyte solutions, and the dependence of these dielectric properties on the composition of the solution, are explained by a conductivity profile in the oxide. It is assumed that a different kind of oxide film is present at the boundary with the solution, which allows electrolyte to enter. The influence of the second-electrode in the solution (normally Pt) used in these measurements is demonstrated or eliminated by using a second identical oxide film instead of platinum. It follows that the unsymmetrical dc current characteristic of the oxide film has no detectable influence on the measured dielectric properties. In addition a treatment of the oxide layers is given, which makes it possible to obtain reproducible results in different kinds of solution over a longer period of time.