Synthesis and Investigations of the Morphology and Structure of Fe 2 O 3 Nanocoatings on Porous Al 2 O 3 Obtained by the Oxidation of Magnetron-Deposited Fe Films

The results of studying the morphology and crystalline, local atomic, and chemical structure of iron(III) oxide coatings on the surface of porous aluminum oxide with different morphology using methods of scanning-electron- and atomic-force microscopy, X-ray phase analysis, X-ray photoelectron spectroscopy, as well as X-ray absorption near edge structure (XANES) spectroscopy are presented. Films of porous alumina are synthesized by the two-stage anodic oxidation of aluminum in 0.3 M aqueous solutions of sulfuric and oxalic acids. To change the pore diameter, some of the films are etched in a phosphoric-acid solution. Samples of iron oxide nanocoatings are obtained by oxidation of iron films in air deposited onto porous alumina substrate matrices by magnetron sputtering at a temperature of 300°C for 3 h. It is shown that oxidation leads to a twofold increase in the coating thickness of the control sample and is associated with an increase in the density of iron oxide compared to pure iron. With a change in the nanoporous structure on the surface of the substrates, the morphological features of the coatings change: there is overgrowth of the pores with iron oxide. Controlling the processes leading to such overgrowth will make it possible to carry out a targeted change in the structure-sensitive properties of composite structures based on iron oxide.