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

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 8-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 degrees C present the best mechanical properties.

Automated summary

Low thermal expansion Li2O-Al2O3-SiO2 transparent glass-ceramics with low Li2O content and relatively high total content of Na2O and K2O were prepared from spodumene, and the effects of Al2O3 addition on their structure and properties were investigated. The addition of Al2O3 promoted the precipitation and transition of 8-quartz solid solution, resulting in smaller grain sizes and higher visible transmittance in the glass-ceramics. Samples with 21.00 wt.% Al2O3 content crystallized at 860 degrees Celsius exhibited the best mechanical properties among all tested samples.