Influences of Al2O3 content on crystallization and physical properties of LAS glass-ceramics prepared from spodumene

Abstract

Low thermal expansion Li2O-Al2O3-SiO2 transparent glass-ceramics with low Li2O content and relatively high total content of Na2O and K2O (> 2.00 wt.%) were prepared from spodumene. And the influences of Al2O3 addition on structure and properties of such LAS glasses and glass-ceramics were investigated. The crystallization behavior and structure of the samples were explored by differential scanning calorimetry (DSC), X-ray diffraction (XRD), magic-angle-spinning (MAS) NMR, Fourier transform infrared spectrometer (FTIR), and scanning electron microscope (SEM). The results show that the addition of Al2O3 contributes to the precipitation and transition of β-quartz solid solution (s.s.) Besides, the smaller grains can be obtained in glass-ceramics with higher Al2O3 content, resulting in the higher visible transmittance. When the Al2O3 content is 21.00 wt.%, the transparent and low coefficient of thermal expansion (CTE) samples crystalized at 860 °C present the best mechanical properties.