Effects of potential and heat treatment on phase transition of alumina dielectric layer

Abstract

The characteristics and growth behaviors of alumina dielectric layer formed by anodic oxidation were investigated. The aluminum oxide layer anodized at 400 V was predominantly amorphous alumina, but at the applied potentials more than 500 V, amorphous and crystalline γ -alumina were existed in anodic oxide layer and the ratio of γ -alumina increased with the increasing applied potential. During the heat treatment at 600 • C or higher temperature, amorphous alumina layer was transformed into the crystalline γ -alumina. The phase transition of anodic amorphous alumina into crystalline depends on anodic applied potentials and heat-treatment temperatures.

Research progress on the preparation of anode foil oxide film for aluminum electrolytic capacitors

“…Oh, H.J. et al [7] explored the structural characteristics of the surface oxide film under different voltages and found that the proportion of γ-Al2O3 in the oxide film increased with the increase of the applied voltage. The composition of the formation solution also affects the structure of the oxide film of the electrode foil.…”