Electroconduction in the Zr|ZrO2| electrolyte system

Abstract

Electroconduction of anodic oxide films on zirconium in 0.1 M Na2SO4 is studied. The films are formed in a galvanostatic regime on single-crystal and polycrystalline iodide-refined zirconium, as well as on electrodes manufactured from a rod obtained by hot extrusion of zirconium iodide melted in an arc furnace and from a plate of iodide-refined zirconium of the I-100 brand. Electrophysical properties of the films are compared on the basis of a model of Frenkel defects, which constitute a system of noninteracting donor centers in the oxide, and a model that describes the formation of a space charge from the donor centers in the oxide (exponential distribution of traps over the films’ bulk). It is shown that experimental current-voltage curves cannot be described by a single model throughout the entire voltage range. At low voltages (<12 V), the Frenkel model is more preferable. In terms of this model, the experimental results can be linearized in the lnI vs. U 1/2 coordinates. At higher voltages, it is more convenient to describe experimental data within the space-charge model in the I vs. U2 or ln(I/U) vs. U coordinates. It is discovered that the technique, which is used for preliminary metallurgical treatment, and the structure of the substrate metal affect parameters of electron conduction in anodic oxide films.