Highly ordered titania nanotube arrays with square, triangular, and sunflower structures.

Focused ion beam guided anodization enables the fabrication of TiO(2) nanotubes in a square arrangement with square cell shapes and in a graphite lattice arrangement with triangular cell shapes, which is impossible through self-organized anodization. TiO(2) nanotubes in sunflower patterns are also obtained, which demonstrates the great potential of guided anodization in fabricating asymmetrical nanotubes.