Résumé:
Passive films formed anodically on tin, in 0.5 M NaOH and in 0.5 M Na2S have been characterised by
electrochemical impedance spectroscopy (EIS) and cyclic potentiodynamic polarization. The observation of the
film formed at surface was done by scanning electron microscopy. In bothes cases the semiconductor properties
of the passive films were investigated by Mott/Schottky plots. The two passive films exhibit n-type
semiconductor behavior. It was seen the differences is found concerning thickness of the space charge region
and the second in the concentration of donors
