Residual glass and crystalline phases in a barium disilicate glass–ceramic

Abstract

Investigations about the presence of residual glass are scarce, despite its fundamental role in the crystallization kinetics and luminescent properties of barium disilicate glass–ceramics (BaO·2SiO2–BS2) with a quasi-stoichiometric composition. Non-isothermal (DTA/DSC) experiments have demonstrated that BS2 presents a polymorphic transformation, where the h-BS2 (monoclinic structure) phase is completely transformed in l-BS2 (orthorhombic structure) at temperatures higher than 1020°C (10°C/min). In this study, BS2 monolithic samples were heat-treated at 1000°C (BS2-10) and 1100°C (BS2-11) in a DSC furnace at a heating rate of 10°C/min. In addition, the crystalline and amorphous phases were characterized and quantified by Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) experiments, respectively. Although the complete polymorphic transformation from h-BS2 to l-BS2 was achieved at 1100°C, our results demonstrated that BS2-11 contains a minor, albeit not negligible, amount of residual glass.