Concurrent sinter-crystallization and microwave dielectric characterization of CaO-MgO-TiO2-SiO2 glass-ceramics

The present work aims to clarify sinter-crystallization behavior and microwave dielectric features of CaO-MgO-TiO2-SiO2 glass-ceramics fabricated via one-step sintering procedure at 800–950°C for 4 h. In this regard, starting glasses were obtained from a conventional melt quenching technique, then subjected to the sinter-crystallization heat treatment. The crystallization behavior of sintered glass-ceramics was studied using X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). On the basis of the obtained results, diopside (CaMgSi2O6) precipitated as the main crystalline phase in all sintered glass-ceramics; however titanite (CaTiSiO5) was found as the secondary crystalline phase in glass-ceramics containing high TiO2 content. The degrees of crystallization of the glass-ceramics prepared procedures were also characterized. Optimized glass-ceramics sintered at 800°C for 4 h showed the maximum relative density of 99%. Further increase of sintering temperature led to gradual decrease of density. The most promising microwave dielectric properties of the sintered glass-ceramics were as εr = 6.8–9.4 and Q × f = 3,735–41,359 GHz