In scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR) examinations it was observed that nanophases, composed of phosphate-rich compositions, are responsible for initiating the nucleation and crystallisation of lithium metasilicate (Li2SiO3) and lithium disilicate (Li2Si2O5) in a high strength lithium disilicate glass-ceramic (Li2Si2O5). This glass-ceramic is free of coloured ions and has a composition (in wt%) of 74.4SiO2, 15.4Li2O, 3.3K2O, 3.5Al2O3, 3.4P2O5. The crystallisation of these two lithium silicate phases was observed by room temperature x-ray diffraction (RT-XRD). Their precipitation in the glass matrix clearly occurs as a parallel solid state reaction. Up to temperatures of 650C, lithium metasilicate dominates as the main phase, and lithium disilicate represents the secondary phase.
