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.