Alumina nanotubes and nanowires from Al-based porous alumina membranes

Using ultrasonic vibrations, we have successfully fabricated alumina nanotubes and nanowires from Al-based porous alumina membranes, which are the products of bulk aluminium in oxalic acid via electrochemical etching. Fine configurations and structures of the alumina nanotubes and nanowires are clearly revealed following a series of atomic force microscope and transmission electronmicroscope observations. Their formation mechanisms are analyzed in detail by comparing different growth characteristics of Al-based alumina membranes with Si-based alumina membranes. Based on our experimental results, we have also pointed out that when using porous alumina templates to fabricate nanostructured materials, it is necessary to carefully distinguish the obtained products from the alumina nanotubes and nanowires.