Liquid-phase separation and crystallization of high silicon canasite-based glass ceramic

The phase separation of high silicon composition 7.6Na2O·4K2O·8.4 CaO·70SiO2·8.9 CaF2·1.0 Al2O3 canasitebased glass ceramic during heat treatment was studied. The crystallization rate of calcium fluoride and canasite was estimated by using quantitative analysis of XRD. The non-isothermal DTA study shows that high silicon content increases the activation energy and restrains the crystallization of canasite appropriately. Through FE-SEM and SAXS, the early stage liquid–liquid phase separation was discovered in this kind of glass ceramic by long time heat treatment at 555 °C. Interestingly, the SAXS result shows that the small scale liquid–liquid phase separation has existed in the glass matrix intrinsically even after quenching.