Self-organized zirconia nanotube arrays prepared by anodization

The zirconia nanotube arrays on zirconium substrates were formed in (NH4)(2)SO4 electrolytes containing different concentrations of NH4F (0.5-2.0 wt%). Highly self-organized zirconia nanotubes can be formed with a diameter ranging from 15 nm to 144 nm and a length of 32 mu m. The morphology of the nanotubes was strongly influenced by the applied voltages and electrolyte concentrations. Electrochemical testing and scanning electron microscope observation indicated the nanotubes were formed due to the competition of zirconia formation and dissolution under the assistance of electric field.