A theoretical and experimental framework for the formation of mixed anodic films on combinatorial aluminium-cerium alloys

Anodizing promises fast, cost-effective, and precise fabrication of mixed metal oxides from alloys of com- plex chemistries and compositions. Applicable to a whole class of valve metals and their alloys, this ver- satile fabrication method has found new dimensions of its applicability to a unique combination of valve and non-valve metals in the quest of finding new applications. Hereby the fabrication of anodic passive films on Al-Ce thin-film combinatorial alloy library covering 1.5 to 10.5 at.% Ce in a phosphate buffer electrolyte having pH = 8.3 is demonstrated. Few nanometre thin dielectric films were attained through the automated localized anodizing using scanning droplet cell microscopy (SDCM). Electrochemical mea- surements suggest a good correlation among alloy composition, film thickness, relative permittivity as well as film resistance. It is inferred that the formation factor, k greater than unity and stable growth of compact composite film is attainable through thermodynamic selection of electrolyte and Gibbs free energy minimization criteria.