Films of porous aluminum oxide obtained by two-stage anodization

Abstract

Anodic aluminum oxide films are widely used to obtain many types of organic and inorganic nanomaterials and are of practical importance in studying the optical properties of nanomaterials synthesized from them. This work presents a method of two-sided and two-stage anodization for obtaining anodic aluminum oxide films with periodic and regularly spaced pores. The method of anodic oxidation of aluminum in solutions of acidic electrolytes makes it possible to quite easily vary the parameters of the porous structure of Al2O3. Oxalic acid was used as an electrolyte for “soft” anodizing of the aluminum plate, and ethyl alcohol and a solution of orthophosphoric acid and chromic anhydride were used to pre-clean and polish the aluminum plate. Anodization was carried out at low temperatures, as a result of which it was possible to obtain an aluminum oxide film with a high degree of ordering of pores, the sizes of which ranged from 60 to 110 nm, and the distance between the pores was in the range of 13–27 nm. Absorption and reflection spectra of a porous film of anodized aluminum were obtained, where good absorption of the films is observed in the short-wavelength region of the spectrum, and the maximum value of the refractive index is observed in the short- and long-wavelength regions of the spectrum