Electrical Condultion and Polarization in Lead Silicate Glasses

Thermally stimulated polarization and depolarization current (TSPC/TSDC) and dc conductivity measurements on a series of lead silicate glasses were made between −196° and 190°C. The general composition of the glasses was xPbO·(100 − x )SiO₂, where x = 30, 40, 45, 50, and 65. The dc conductivity exhibits a monotonic increase with increasing PbO content. For x > 45, the rise in conductivity with increasing PbO content is much less than for x < 45. Two TSDC peaks have been observed in all the glasses. The smaller of the two TSDC peaks, occurring at lower temperatures, increases linearly in size with increasing concentrations of PbO. The high-temperature TSDC peak does not saturate from −196° to 190°C. Direct current conductivity in these glasses is ionic and due to the motion of Pb²⁺ ions. The behavior of the low-temperature TSDC peak is consistent with the hypothesis that it is caused by short-range motion (orientational polarization) of Pb²⁺ ions. The origin of the high-temperature TSDC peak is tentatively attributed to space charge polarization of Pb²⁺ ions.