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

•Explore the structures and properties of CMBAS glasses by combining experiments with MD simulations. The chemical environment of boron is well reproduced in our simulations.•The aluminum coordination states are set to mostly four-coordinated from the original potential fitting process, [3]Al and [5]Al units trends in experiments are not well reproduce. This provides a suggestion on future potential development.•Magnesium plays the role of both network modifiers and charge compensators in CMBAS glasses. Aluminum is preferentially charge-compensated by magnesium ion. Magnesium prefers to bond with NBOs and has relatively poor charge compensation ability for boron.•Magnesium can form stronger and shorter bonds with oxygen atoms thus increasing the atomic packing density. Additional boron increases [BO3] structures which is not conducive to form close packing with tetrahedral structures, and result in rapidly decreasing elastic moduli of the glasses. 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.