Glass-ceramics in the LAS (Li2O-Al2O3-SiO2) system with high thermal shock resistance were successfully obtained using Brazilian spodumene concentrate as the main raw material (80-70 wt%). Two compositions (Li2O.Al2O3.nSiO2) were produced with n= 2 and 4, near to the stoichiometric compositions of β-eucryptite and β-spodumene. The characteristic temperatures of parent glasses were determined by contact dilatometry, differential scanning calorimetry and heating microscopy. The crystallization mechanism and the effect of the nucleating agent (TiO2.2ZrO2) required to promote volume crystallization in the parent glasses were investigated. Microstructural and structural changes with temperature were also evaluated by optical microscopy and X-ray diffraction. The obtained glass-ceramics presented coefficients of thermal expansion between -0.370x10-6 and 4.501x10-6 °C-1 in the 22 to 700 °C range.

The influence of nucleating agents and heat‐treatments on magnesium‐aluminum‐silicate (MAS) glass‐ceramics was studied. MAS precursor glasses were melted in oxidant (air) and reducing atmospheres. Nb2O5, MoO3 and TiO2+ZrO2 were added as nucleating agents at the same molar proportion (1.0%). MAS glass‐ceramics nucleated with Nb2O5 are strike face candidates for security windows when relevant outputs are taken into account, such as transparency, crack resistance, hardness and feasibility. Nb2O5‐doped MAS can achieve up to 20% crystalline volume fraction, while keeping the visible transparency close to 70%. Knoop hardness was raised up to 7.4 GPa in comparison to precursor glass (6.2 GPa), considering the indentation size effect. The crack resistance reached 4 N.

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