Changes of the Electrical Properties of the Systems PbO-ZnO-B₂O₃ and PbF₂-ZnO-B₂O₃ during Heat-treatment

Abstract

For the purpose of obtaing a low loss sintered glass-ceramics, behaviors of oxide and oxyfluoride glasses during heat-treatment were investigated. The systems investigated were PbO-ZnO-B₂O₃ and PbF₂-ZnO-B₂O₃. From the oxide glass, 2PbO⋅ZnO⋅B₂O₃ was crystallized by heat treatment, while from the oxyfluoride glass the oxyfluoride crystal contaming Pb and Zn was crystallized primarily after phase separation due to spinodal decomposition and then this crystal transformed to PbO⋅2ZnO⋅B₂O₃.
Volume resistivity and activation energy of electrical conduction of the oxide glass decreased, as crystallization proceeded, and on the other hand, those of the oxyfluoride glass increased as oxyfluoride crystal appeared, but when the crystal transformed to PbO⋅2ZnO⋅B₂O₃, by further heat-treatment at higher temperatures, volume resistivity and activation energy decreased sharply.
Main conduction mechanism of the oxide glass was considered as cationic conduction related to Na⁺ ions, and that of oxyfluoride glass was anionic or vacancy conduction that related to F^- ion, or F^- vacancy or F^- interstitial.