In this Letter, we demonstrate that the spontaneous nanophase-separation can greatly enhance the heterogeneous nucleation in the investigated phosphosilicate melts. The two separated phases are found to be the phosphate-rich phase as the floppy domain and the silicate-rich phases as rigid phase. We found that sodium phosphate nanocrystals form in the phosphate-rich phase during melt cooling. The growth of these nanocrystals are self-limited, i.e., limited by the surrounding silicate-rich phase with higher viscosity, and hence lower ionic diffusion compared to the phosphate-rich phase. Our results show that the substitution of B 2O 3 or Al 2O 3 for partial Na 2O enhances the spontaneous nucleation, although the viscosity of silicate-rich matrix phase is increased by such substitution. This implies that the compositional substitution enhances nanophase separation and thereby lowers the activation energy for non-isothermal crystallization. This work indicates that nanophase separation is crucial for fabrication of transparent glass-ceramics from phosphosilicate melts.
|Tidsskrift||Journal of the European Ceramic Society|
|Status||Udgivet - okt. 2019|