Phase separation and crystallization of borosilicate glass enriched in MoO3, P2O5, ZrO2, CaO

Borosilicate glasses with high molybdenum, phosphorus, calcium and zirconium oxide concentrations are partially crystallized. Their final microstructure reveals the contribution of microphase separation and crystallization phenomena during cooling. Rapid quenching of melts between copper rollers and by air blowing was investigated at various melting temperatures. The microstructure of glass specimens was characterized by transmission electron microscopy (TEM) and scanning electron microscope (SEM) coupled with and EDS analyzer. Glass transformation mechanisms during cooling are proposed: initial microphase separation at high temperature probably occurring though a nucleation and growth mechanism, followed by coalescence of the separated droplets.