Calculation of subliquidus miscibility gaps in the Li2O–B2O3–SiO2 system

A thermodynamic approach of predicting the binary and ternary subliquidus miscibility gaps of the Li2O–B2O3–SiO2 system is described. For the binary B2O3–SiO2, Li2O–B2O3, and Li2O–SiO2 systems, according to the shape of liquidus and the location of subliquidus miscibility gaps, a simple model such as regular, quasi-regular, and subregular solution models is applied to describe the liquid phase. The present calculations agree with experimental data available in the literature. The ternary subliquidus miscibility gaps with tie lines were calculated by applying the Toop–Muggianu method which uses the binary systems. In the present calculations, the isothermal sections of the subliquidus miscibility gaps in the ternary systems were reasonable in the aspect of the development of both the tie lines and the critical points according to changing the temperature. Also, the composition range was calculated where spinodal decomposition is possible.