Effect of Li₂O on phase transition and properties of BAS (BaO-AlO-SiO system) glass-ceramics

For the transforming hexacelsian into celsian during crystallization of BAS gel glasses, the optimum is reached by preparing BAS glass-ceramic containing 1 wt% of Li₂O: such BAS glass-ceramic possesses the following good properties: room temperature flexural strength 139MPa, 1200°C flexural strength is 148 MPa and linear expansion coefficient 4.9×10^-6/°C. The selection of 1 wt% of Li₂O as optimum is based on the consideration that, while keeping the above three properties satisfactory, it can transform as much hexacelsian into celsian as possible.