Characterization of titanium oxide thin films anodicaly grown in phosphoric acid

-Ti-Cu(2%) alloy was anodized in a 5 M phosphoric acid solution under various voltages ranging from 10 to 3 5 V. The composition, the structural and optical properties of the as grown oxide films were studied. It was found that the color of the anodized substrates varied from yellow to blue depending on the anodizing voltage. The films formed on the alloy are amorphous and the oxidation state of Ti on their surface is mainly +4. On the other hand it was found that the thickness of the films increases linearly with anodization voltage at rate of 1.94 nm/N, while the refractive index at the wavelength corresponding to the reflectance minimum was practically constant. These films were also found to have excellent protective properties for the examined alloy.