In this work, the growth of antimony oxide films on Sb in chloride solutions in a wide range of conditions for oxide growth is analyzed. Electrochemical impedance spectroscopy (EIS) as well as ellipsometric results for the anodic films are correlated with the morphology obtained by AFM. As opposite to results obtained in phosphate solutions where anodic films are essentially homogeneous in thickness, porous films are obtained in chloride solutions. Impedance results are compared with predictions of models in terms of passive electronic elements in electrical equivalent circuits. Impedance results are interpreted in terms of the Surface Charge Assisted High-Field Migration Model2 (SCAHFMM) for anodic film growth. Porous structure is also incorporated in the impedance analysis and equivalent circuits for taking into account the formation of pits (“active pit model”3,4) are proposed. The dependence of the values obtained for the different circuit elements with film formation potential and electrolyte concentration is also discussed. Film porous nature and its dependence with formation conditions are corroborated by AFM.
