Electrochemical and spectroelectrochemical properties of methylendioxy-phenoxy-substituted novel lutetium (III) mono- and bis-phthalocyanines
By Bozoğlu, Ceyda; Arıcı, Mürsel; Uğur, Ahmet Lütfi; Erdoğmuş, Ali & Koca, Atıf
Published in Synthetic Metals
2014
Abstract
High impedance organic coatings may behave differently from a pure capacitor at the beginning of immersion when studied by electrochemical impedance spectroscopy (EIS). A phase shift is then obtained in the high frequency domain of the phase Bode plot which makes water uptake estimation difficult. In some cases, the analysis of EIS spectra when considering constant phase elements (CPEs), dielectric relaxation or thickness profile is not sufficient. In this work, we propose a model to represent high impedance thick organic coatings constituted with a dry part of the coating, in contact with the substrate and a humid part in contact with the electrolytic solution. Water is assumed to be uniformly distributed in the humid part of the coating while a resistivity decrease is considered in the dry part. Finally, a Young impedance in series with a humid film (RC) constant is obtained and compared to experimental results.