关键词: TiO2氧化膜, 氧空位点缺陷, 扩散系数, 电容测量, Mott-Schottky分析

Abstract: The ionic charge transfer properties of the oxygen vacancy point defects in TiO2 films formed on titanium were studied in 1.0 mol·L-1 HClO4 solution with cyclic voltammetry,potentiostatic polarization,galvanostatic reduction and capacitance measurements. The measured capacitance data were analyzed based on the Mott-Schottky equation and Einstein equation. Based on the different response times to the changes of the applied electric field between the ionic and the electronic charge transfers,the diffusion coefficient of the point defects in the anodic oxide film on titanium was estimated. It was shown that the passive potential region for titanium in 1.0 mol·L-1 HClO4 ranged from ca. 0 to 6 V. Some important physico-chemical properties in relation with the point defects (oxygen vacancy) transfer,such as the steady-state current (iss),the film oxidization factor (α),the field strength within the film () and the diffusion coefficient of the oxygen vacancies (DO),were found to be potential-dependent. The effects of anodic oxygen evolution and of the film structure changes at higher potentials on the film bulk properties were also discussed.

Key words: TiO2 film, oxygen vacancy defects, diffusion coefficient, capacitance measurements, Mott-Schottky analysis