Molecular dynamics simulations study on structure and properties of CaO–MgO–B2O3–Al2O3–SiO2 glasses with different B2O3/MgO

Abstract

CaO–MgO–B2O3–Al2O3–SiO2 glasses are of great important in glass fiber industry. In this work, the structures, thermal stabilities, and elastic moduli of the glasses are studied using molecular dynamics (MD) simulations by gradual substitution between B2O3 and MgO. The results show that with the increase of the ratios of B2O3/MgO, aluminum shows complex coordination changes, but the four-coordination aluminum is still the dominating specie. The boron coordination environment does not change significantly with the substitution and the three-coordination boron keeps staying at a high level. The percentages of bridge oxygen and network connectivity (NC) in the glasses increase with the increase of B2O3/MgO ratios, which enhances the glass network and improve the thermal stabilities. The elastic moduli calculated from simulations are in good agreement with the experiments. The study shows that high content of Mg2+ can increase atomic packing density. The introduction of boron brings more [BO3] structures, which further weakens the stiffness of the glass network. Insights of the effect of B2O3/MgO ratios on the structures and properties will facilitate the development of high-performance glass fibers.