Effect of Y2O3/La2O3 on structure and mechanical properties of Li2O-Al2O3-SiO2 glass

Effect of Y2O3 and La2O3 substitution for SiO2 on the structure and mechanical properties of Li2O-Al2O3-SiO2 (LAS) glass was investigated. The structural changes were characterized by 27Al magic angle spinning nuclear magnetic resonance (MAS-NMR), Fourier transform infrared spectrometer (FTIR) and viscosity-temperature tests. The results showed that LAS glass network structures depolymerized firstly and then polymerized with increasing Y2O3 or La2O3 content. Atomic packing density of LAS glasses monotonically increased as the addition of Y2O3 or La2O3 and its best measurement value is 0.5824 with the Y2O3 and La2O3 doping content are 4 mol% and 2 mol% (denoted as LAS-42). Simultaneously, Vickers hardness, elastic modulus and bending strength were measured and their best values corresponded to 712.80 HV, 99.72 GPa and 140.47 MPa when the glass is LAS-42, with the increases of 13.1%, 14.9% and 59.9%, respectively. This study revealed that high dissociation energy oxides, in terms of Y2O3 and La2O3, have obvious effects on improving mechanical properties of LAS glass.