Thermodynamic Functions of the Anodic Oxidation Reactions of Niobium and Tantalum

In this paper, we develop the thermodynamic models of electrochemical oxidation of niobium and tantalum that allow predicting the composition of their anodic oxides depending on the electrolyte composition. The reactivity of metals with respect to electrolyte anions was evaluated. It was revealed that doping additives can be included in the composition of anodic oxide films of Nb and Ta depending on the nature of the anions supplied by the electrolyte components. The thermodynamic modeling results will allow predicting the component compositions of anodizing solutions to obtain anodic oxide films of these elements with a specified composition.