Transparent glass-ceramics derived from spontaneously crystallized phosphosilicate glasses

Transparent phosphosilicate glass-ceramics were prepared by heating the spontaneously crystallized precursor glasses in which crystals have formed during cooling of the melts. And the effects of compositional variation on the crystalline phases, degree of crystallization and transparency were investigated by using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). It is found that Mg2+ tends to exist in silicate-rich phase rather than phosphate-rich phase, such MgO is more beneficial to the transparency of phosphosilicate glass-ceremics compared to CaO. In addition, the substitution of P2O5 for SiO2 enhances the tendency of phase separation, and hence the precipitation of Na2MgSiO4 crystals for the precursor glasses as well as glass-ceramics with good transparency.