The preparation of transparent Cristobalite glass ceramics by substituting Li2O with MgO

This study investigates the impact of substituting MgO for Li2O in LAS glass ceramics, and successfully producing transparent glass ceramics with a Cristobalite phase. The visible light transmittance at 550 nm is measured at 88.3 %, while the Vickers hardness is recorded at 7.14 GPa. Substituting MgO for Li2O strengthens the glass network, which complicates the process of crystallization. The crystallization mode shifts from bulk to surface crystallization. The substantial thermal expansion mismatch between Cristobalite and the glass matrix results in cracking, thereby limiting the crystallinity of Cristobalite glass ceramics. Furthermore, regarding the samples with surface crystallization, phase separation occurs in the uncrystallized regions. FT-IR analysis indicates that heat treatment promotes a trend toward ordering in the material. The relatively regular interface of surface crystallization led to some crystals exhibiting a directional arrangement. This is the most orderly crystal arrangement observed in the reviewed glass ceramics.