Molecular dynamics simulations study on structure and elastic property of alkali-free aluminoborosilicate glasses with different Al2O3/(MgO+CaO) ratio

The effect of Al2O3/(MgO+CaO) ratio on structure and elastic modulus of CaO-MgO-Al2O3-B2O3-SiO2 (CMABS) glasses were investigated by combining molecular dynamics simulations, Makishima-Mackenzie model and experiments. With the increase of Al2O3/(CaO+MgO) ratio, the main coordination number of Al3+ and Si4+ was four, while more than 79 % of B3+ existed in the form of [BO3]. The bridging oxygen and tri-cluster oxygen showed an overall increasing trend and the large rings transformed into smaller rings, both of which indicated the increaseing network connectivity and network polymerization. The dissociation energy of glass samples also showed an increasing trend. Therefore, with the increase of network polymerization and dissociation energy, the elastic modulus increased from 83.2 GPa to 89.85 GPa. The elastic modulus of CMABS glasses calculated by the molecular dynamics simulations and Makishima-Mackenzie model differ within 10 % from the values tested, and they have the same trend of variation.