Eletrical Properties of Glasses in the System PbO-Al2O3-B2O3-SiO2

Glasses in the system Pb0–Al₂O₃-B₂O₃-SiO₂ are chemically stable over a wide composition range and have very desirable electrical characteristics such as high electrical resistivities and activation energies for conduction. Variations in these electrical properties were studied as a function of composition changes within the system, the object being to identify the role of the constituent oxides in achieving the highest activation energy and resistivity values consistent with moderate preparation temperatures. Measurements were made in the temperature range 25° to 400°C on carefully prepared glass disks in which the individual oxide components or different oxide ratios such as PbO/SiO₂, Al₂O₃/SiO₂, and B_sO₃/SiO₁ were systematically varied. The activation energy and resistivity values obtained ranged from 1.2 to 1.6 ev and 10° to 10¹⁴ ohm-cm, with dielectric constants ranging from 9 to 19 and densities from 4.30 to 4.50 g/cmY. Indications were that, for the composition range studied, the behavior manifested was basically that of the binary PbO-SO₂ glass with additions of Al₂O₃ or B₂O₃, even in small concentrations, sharply increasing the activation energy for conduction while lowering the density.