Na2O/Li2O Ratio Dependency on the Thermal, Mechanical, Dielectric Properties and Chemical Stabilities of Li2O-Al2O3-SiO2 Glass

Li2O-Al2O3-SiO2 based glasses were investigated as potential protection glass for electronic devices due to their excellent mechanical properties, such as high hardness, toughness, and scratch resistance. In this paper, Li2O-Na2O-Al2O3-SiO2 glass with different Li2O/Na2O ratio components were prepared by melt-quenching method, and the effects of Na2O/Li2O ratio on the glass densities, structure, thermal, mechanical properties, and chemical stabilities were studied. The experimental results indicate that the glass transition temperature increases with the increases in Na2O/Li2O ratios, due to larger ion radius. While the thermal expansion coefficient slightly decreases from 11.4 x 10(-6) to 11.09 x 10(-6)/degrees C. The elastic modulus increases from 57 to 72 GPa. The bending strength reaches maximum 80.90 MPa when the Na2O/Li2O ratio is 1.7, then decreases as the ratio further increases. In addition, the Vicker's hardness gets to 7.37 GPa with largest Na2O/Li2O ratio. Moreover, the dielectric loss and dielectric constant increases as the ratio increases. The Raman structure analysis shows the Q(4) [Si-O-Si] decreases as Na2O/Li2O ratio increases, which is responsible for the characteristic properties change. Moreover, the glass shows lowest mass loss in 10vol% HF solutions when the ratio is 1.4, while 1.7 in 5wt% NaOH solution.