Analysis of the Changes in Stabilization in Accordance with Division and Expansion over Time of TiO₂ Nanotube Arrays Fabricated by Using Anodization

In this research, TiO₂ nanotube arrays were fabricated by using anodization. The change in alignment due to the change in the diameter of the nanotube bottom in accordance with anodization time was analyzed by using field emission scanning electron microscopy. Individually separated TiO₂ was confirmed to have formed in the initial stage of anodization. In this process, the expansion and division of the nanotube proceeded with the prolongation of anodization time. As large-diameter nanotubes divided, the distribution values of the diameters decreased, and the stability degree tended to improve. With the passage of time, when the division of the nanotube had been completed to some extent, the expansion of the nanotube proceeded more predominantly, and the average diameter tended to increase. These findings confirmed that the time of anodization affected the alignment and that the bottom diameter was randomly generated at the beginning. Moreover, during TiO₂ nanotube growth, the bottom part not only expanded but also split.