Influence of passive potential on the electronic property of the passive film formed on Ti in 0.1 M HCl solution during ultrasonic cavitation

The influence of the applied passive potential on the electronic property of the passive film formed on Ti at different potentials in 0.1 M HCl solution during ultrasonic cavitation, was investigated by electrochemical impedance spectra (EIS) and Mott–Schottky plot. The influence of the applied passive potential on the structure and composition of the passive film was studied by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The results showed that the applied passive potential can obviously affect the electronic property of the passive film formed on Ti during ultrasonic cavitation. The resistance of the passive film increased, and the donor density of the passive film decreased with increasing the potential. The flat band potential moved to positive direction and the band gap of the passive film moved to negative direction with increasing potential. AES and XPS results indicated that the thickness of the passive film increased evidently with applying passive potential. The passive film was mainly composed of the mixture of TiO and TiO2. While the TiO2 content increased with increasing the applied passive potential, and the crystallization of the passive film increased with the increased potential.