Electroinduction of Peculiar Space-Charge Regions in Fully-Glassy Lead Oxyfluoroborate Materials Discerned from Impedance Spectroscopy

Abstract

Lead oxyfluoroborate (BO1.5–PbO–PbF2) glasses were prepared and studied in this work in terms of dielectric response. By applying impedance spectroscopy, this study shows that electric field-induced peculiar space-charge regions form in these glasses, in the bulk adjacent to the glass–electrode interfaces. In addition, submission of these glasses to the action of a long-term electric field results in development of surface crystallization, even below the glass transition temperature. Evidence has been given in the literature that such a phenomenon involves electric field-induced redox-type electrochemical reactions that develop, simultaneously, at both glass–electrode interfaces, promoting β-PbF2 crystallites nucleation toward the cathode side. Accordingly, it is here concluded that the above mentioned space-charge regions should incorporate those electroactive species that look forward to participate in the redox reactions that subsequently promote incidence of this non-spontaneous crystallization phenomenon.