Electrical properties of Lithium silicate-based glasses and their Glass-ceramics

Abstract

Crystallization of lithium di- and meta-silicates were developed in the SiO2–Li2O–TiO2 glass system. Inclusion of TiO2 relatively reduced the crystallization temperature. Through the sintering process at 650 °C/2 h, lithium disilicate was devolved in the TiO2-free sample, whereas the incorporation of TiO2 catalyzed the appearance of lithium metasilicate phases. The microstructure of lithium disilicate glass-ceramics was studied using differential thermal analysis (DTA), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). At 650 °C/2 h, the microstructure consists of spherulitic growths with reasonably sorted nanosize particles in a glassy groundmass. The electrical characteristics of lithium silicate glasses and glass-ceramics having variable concentrations of TiO2 were tested in order to explore their electronic hopping process. To clarify the effects of composition and sintering on the electrical and dielectric behavior of glasses based on lithium silicate, a Broadband Dielectric Spectroscopy (BDS) was employed. While the matching-sintered glass-ceramic exhibits like an insulator with interfacial polarization that significantly lowers the density number of free ions, bulk glass nevertheless demonstrate high conductivity. Lithium oxide considerably increases the conductivity of the composite instead of titanium oxide.