Nanofabrication of metal oxide thin films and nano-ceramics from aqueous solution

Abstract

Two-dimensional graded metal oxide films with highly ordered periodic structure have been prepared from aqueous metal–fluoro complex solutions by liquid-phase infiltration (LPI) in aqueous solution. Films were deposited from solution, in which a (NH₄)₂TiF₆ solution was added at a controlled flow rate in an FeOOH–NH₄F·HF solution. Field emission scanning electron microscopy (FE-SEM) reveals that the resultant graded oxide structures have highly nano-ordered architectures and represent negative or positive replicas of the template. Transmission electron microscopy (TEM) and X-ray microanalysis of the films revealed that the present technique enabled wide-range control of the composition and graded profile of the deposited films in the depth direction. Along with the change in composition, the microstructure of the films changes from microcrystalline β-FeOOH at the base to nanocrystalline anatase-TiO₂. The LPI process is conducive to the preparation of advanced nanoceramics with highly ordered structures.