Preparation and properties of transparent cordierite-based glass-ceramics with high crystallinity

Transparent cordierite-based glass-ceramics with high crystallinity were prepared successfully. The crystallization kinetics of parent glass was deeply investigated by differential scanning calorimetry (DSC). After heat-treatment at 1030 °C for 6 h, a large amount of α-cordierite (indialite) crystals devitrified from the parent glass, which was confirmed by the X-ray diffraction and TEM results. The crystallinity of the obtained transparent glass-ceramics reached up to 87.5%, which can be ascribed to the composition and heat treatment of parent glass. The high transparency of glass-ceramics mainly resulted from the small difference of refractive index between α-cordierite and the parent glass. In addition, these transparent glass-ceramics possessed low density (2.477 g/cm3), low thermal expansion coefficient (1.435×10−6 °C−1) and high Vickers hardness (8.1 GPa). The combination of excellent physical, thermal and optical properties makes this new family of transparent glass-ceramics exhibiting potential applications in the fields of base materials for rare-earth ions.