Crystallization and microstructural characterization of B2O3–Al2O3–SiO2 glass

Glass containing B2O3–Al2O3–SiO2–Li2O–K2O was prepared by conventional melting and annealing technique, and converted to transparent glass–ceramics by controlled nucleation and crystallization process. The nucleation and crystallization temperatures were determined by differential thermal analysis. X-ray diffraction was used to determine the crystal phases. Scanning electron microscopy was used to study the glass–ceramics morphology, the grain size and distribution in the residual glass. Infrared spectroscopy was used to confirm the reorganization of amorphous solid. X-ray photoelectron spectroscopy was used to determine the valence state of element. The transmittance was measured by UV–Vis–NIR scanning spectrophotometer. Two main crystal phases including Al4B2O9 and Al20B4O36 were observed in all samples. The change in B2O3/Al2O3 ratio has little influence on the crystal types of the B2O3–Al2O3–SiO2 glass–ceramics. B atoms existed in the form of [BO3] and [BO4]. Al existed in the forms of [AlO4] and [AlO6], and forming network together with [SiO4] tetrahedron. The transmittance of BAS glass–ceramics reached 90% at visible and infrared wavelength, and cut-on absorption at ultraviolet and cut-off absorption at infrared wavelength were observed.