Mixed Alkaline Earth Effect on the Structure and Elastic Modulus of CaO–MgO–Al2O3–SiO2 Glasses: A Molecular Dynamics Simulation

The influence of mixed alkaline earth effect on the atomic structure and elastic modulus of the CaO-MgO-Al2O3-SiO2 glasses were studied by molecular dynamics simulation. The elastic modulus values ob-tained from the simulation of uniaxial tension and stiffness tensor methods showed the same trend with the change of composition, while the simulated results of the former were closer to the measured data. The variation trend of Qn species obtained by the simulation and Raman spectroscopy was consistent. Ca and Mg cations were more inclined to form non-bridging oxygen when the Ca/Mg ratio exceeded 1, which damaged the tetrahedral connection and further reduced the degree of network polymerization. The ratio of non-bridging oxygen to tetrahedrally coordinated cations (NBO/T) used to characterize the degree of polymerization was found to have a linear relationship with the elastic modulus. In addition, the local cluster of modifier atoms was beneficial to increase the elastic modulus values.