Solid-State Anodic Oxidation of Tantalum

When an anodic potential is applied to a tantalum point contact to , the current‐voltage behavior is analogous to that observed during the anodic oxidation of a valve metal in an aqueous electrolyte. It is proposed that this represents a solid‐state anodic oxidation whereby tantalum oxide is formed at the expense of the local oxygen content of the , and that this process represents an important "healing" mechanism in the solid electrolyte capacitor. This process requires that the conductivity of the reduced manganese oxide phase, which must be formed adjacent to the , have a finite ionic portion, and experimental support for this is described. The current efficiency of the solid‐state anodization is very low and is dependent on ambient moisture. Similar behavior has been found for aluminum and niobium point anodes and with as the cathode.