Effect of La2O3 on structure and chemical strengthening properties of Li2O–Al2O3–SiO2 glass: experiment and simulation

Abstract

This study systematically investigates the regulatory effect of La₂O₃ on the structure, mechanical and chemical strengthening properties of lithium aluminosilicate (LAS) glass through experiment and molecular dynamics (MD) simulation. MD simulations demonstrate that La₂O₃ incorporation enhances network densification through the high field strength of La³⁺ (Z/r²=2.82). The main coordination number (CN) of La atoms is 6, which dynamically changes to 5∼8 with the increase of content, and the bond length of La-O is shortened from 2.24 Å to 2.21 Å and then increased to 2.31 Å. When adding 1.0 mol % La₂O₃, the Vickers hardness and bending strength of glass are as high as 7.15 GPa and 205 MPa, respectively. However, the excessive La₂O₃ (>1.0 mol %) destroys the connectivity of [SiO₄] network and reduces the proportion of Q⁴. With the increase of La₂O₃ content, the chemical strengthening results show that the surface compressive stress decreases linearly. In contrast, the depth of the stress layer (DOL) decreased first and then increased, attributed to the “densification-depolymerization” competition mechanism of La₂O₃ in LAS glass. Results provide the theoretical guidance for development of LAS glass containing rare earth oxides that have highly effective chemical strengthening properties.