Crystallization characteristic and properties of some zinc containing soda lime silicate glasses

The crystallization behaviour of some soda lime silicate glasses modified by ZnO/CaO replacement to give the composition (Na2O)2·CaO1−x·(ZnO)x·3SiO2 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) have been investigated using differential scanning calorimetry (DSC) and X-ray diffraction analysis (XRD). The thermal expansion coefficients and AC electrical properties in the frequency range 40 Hz–5 MHz of the obtained crystalline products were determined. Two forms of sodium calcium silicate (Na4CaSi3O9 & Na2Ca2Si3O9), sodium metasilicate-Na2SiO3, two types of sodium zinc silicate (Na1.31Zn0.655Si1.345O4 & Na2ZnSiO4) and α-quartz phases were mostly developed in the crystallized glasses using various heat-treatment processes. The coefficient of thermal expansion of the obtained glass–ceramic materials are between 120 × 10−7°K−1 and 168 × 10−7°K−1 in the 25°–600 °C temperature range. The increase of frequency generally resulted in the increase of the conductivity and decrease the dielectric constant together with the loss tangent of the glass–ceramic materials.