Structural response to densification of Na2O-Al2O3-SiO2 glasses with different load indentation centers

The Vickers indentation centers of glass have a general densification effect, and their ability to dissipate stress significantly influences the crack resistance and toughness of the glass. In this study, we used Raman spectroscopy and molecular dynamics simulations focused on the Vickers indentation center of Na ₂O-Al ₂O ₃-SiO ₂ glass to investigate its structural contribution to densification. The indentation load and depth were both controlled .Results showed that as the loading increases, the structure of the glass densification zone shrinks (decreased spacing of silica-oxygen tetrahedra close to each other and Si-O-Si bond angles) and reorganizes (by ring distribution, or bridging oxygen distribution).The non-bridging oxygen(NBO) content increases with increasing degree of densification, and the corresponding modifier ions fill the original void space, indicate the occurrence of shear behavior during densification. Furthermore, Al tetrahedra inhibit NBO production during indentation. These findings jointly contribute to the study of the cracking behavior of glass.