Effect of Al2O3/Na2O ratio on structure, elastic modulus and thermal expansion of Na2O-MgO-Al2O3-SiO2 glasses studied by molecular dynamics simulations and experiments

Y Guo and WK Gao and ZY Kang and W Xue and YS Hou and C Jing and XY Li and Z Shuo and YL Yue and JF Kang, JOURNAL OF NON-CRYSTALLINE SOLIDS, 659, 123524 (2025).

DOI: 10.1016/j.jnoncrysol.2025.123524

In this study, molecular dynamics simulations and experiments were jointly employed to investigate the effects of increasing Al2O3/Na2O ratio on the structure, elastic modulus, and coefficient of thermal expansion (CTE) in the Na2O-MgO-A12O3-SiO2 glass system. The results showed that with the increase of Al2O3/Na2O, the content of bridging oxygen (BO) and tri-cluster oxygen (TO) increased, while non-bridging oxygen (NBO) attached to SiO4 was preferentially converted into bridging oxygen. The medium-range structural units Qn transformed according to the equation Q3 + Q2 -> Q4. Concurrently, the ring size changed from large rings to smaller rings, which indicated the increase of glass network connectivity. As the Al2O3/Na2O ratio increased, the elastic modulus of samples increased significantly, while CTE decreased. The simulated properties exhibited trends consistent with experimental results. In addition, the ratio of non-bridging oxygen to tetrahedral coordination cation (NBO/T) was linearly correlated with elastic modulus and CTE.

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