Influence of nucleating agents on crystallization and electrical properties of SiO2–MgO–MgF2–K2O mica glass-ceramics

The effects of adding ZrO₂ and TiO₂ at the expense of MgF₂ on the crystallization, microstructure, mechanical properties, thermal properties and electrical properties of mica glass-ceramics based on the SiO₂–MgO–MgF₂–K₂O system were investigated by the differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), microhardness tester and resistivity tester. The electrical properties were discussed emphatically. The results showed that the additions of ZrO₂ and/or TiO₂ at the expense of MgF₂ effectively increase the viscosity, the glass transition temperatures (T_g) and the crystallization temperatures (T_p) of the glasses. The crystallization activation energy (E_c) of the amorphous glasses varied with the nucleating agents was discussed in depth. It was discovered that the nucleating agents had no effect on the crystal phase type but had a certain effect on the crystallinity and microstructure. Tetrasilicic fluoromica and enstatite were precipitated at different crystallization temperatures. Due to the non-stoichiometric ratio of tetrasilicic fluoromica crystal, the prepared glass-ceramics had high dielectric constant (24.4–34.3) and volume resistivity (>2 × 10¹¹ Ω cm) at 25 ^°C, and the dielectric loss was almost zero.