Formation of crystalline TiO2 by anodic oxidation of titanium

Formation of crystalline TiO2 (anatase) films by anodic oxidation of titanium foils in ethylene glycol (EG) based electrolytes at room temperature has been investigated. By varying the anodizing parameters such as the amounts of water and NH4F added, applied voltage and anodization time, anodic TiO2 films with different crystalline structures were obtained. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray powder diffraction (XRD) characterizations were employed to determine the morphologies and crystalline structures of as-prepared anodic TiO2 films. The results indicate that crystallization of anodic TiO2 films was generally facilitated by high fluoride concentration, high applied voltage and longer anodization time, and the formation of anodic TiO2 films with best crystallinity could only be achieved when optimized amounts of water were added.