Electrochemical and semiconducting properties of thin passive film formed on titanium in chloride medium at various pH conditions
By Balakrishnan Munirathinam and R. Narayanan and Lakshman Neelakantan
Published in Thin Solid Films
2016
Abstract
The electrochemical behavior of titanium has been investigated in chloride electrolyte of different pH values (2.1, 5.2 and 7.4). Potentiodynamic polarization studies showed wide passive behavior irrespective of change in pH. Passive films were grown by applying different passive potentials (0.2 to 0.6 V (vs SCE)) by recording chronoamperometric curves for duration of 8 h. Electrochemical impedance spectroscopy (EIS) measurements showed higher impedance values for the oxide layer grown in neutral pH condition and for oxides formed at higher formation potentials. Emphasis is made mainly on the properties of titanium oxide estimated by Mott-Schottky analysis, which shows that passive film formed, is of n-type semiconducting film and the donor concentration is in the order of 1020 cm? 3. The calculated diffusivity of point defects is in the range of (0.5 to 2.5)