Electrical conduction and polarization of silica-based capacitors under electro-thermal poling

Electrical conduction in silica-based capacitors under a combined effect of intermediate electric field and temperature (2.5 – 10 kV/mm, 50-300°C) is dominated by localized motion of high mobility ions such as sodium. Thermally stimulated polarization and depolarization current (TSPC/TSDC) characterization was carried out on poled fused silica and AF32 glass samples. Two relaxation mechanisms were found during the depolarization step and an anomalous response for the second TSDC peak was observed. Absorption current measurements were performed on the glass samples and a time-dependent response was observed when subjected to different electro-thermal conditions. It was found that at low temperature (T = 175 °C) and short times, the current follows a linear behavior (I α V) while at high temperature (T = 250 °C), the current follows V0.5. TSPC/TSDC and absorption current measurements results led to the conclusion that (1) Poole-Frenkel dominates conduction at high temperatures and at longer times and that (2) ionic blockage and/or H+/H3O+ injection are responsible for the observed anomalous current response.