Optical Studies of the Anodic Passivation of Tin

Abstract

Thecomplex dielectric constant and the thickness of the passive filmgrown on tin in borate buffer solutions have beendetermined usinga reflectometric technique. The effect of growing potential and energyof the incident light have beenanalyzed and correlated with previousresults. The film was found to undergo rapid changes inhydration near the onset ofpassivity. The density of the filmremains constant above 0.2V. It is smaller than that ofcrystalline tin oxides. From thethickness dependence of the electrode capacitancethe dielectric constant, , was calculated as a function ofthe frequency ofthe a-c modulating signal, . The results showa linear dependence of on log . ©1982 The Electrochemical Society, Inc.