Video recording of in situ high temperature optical microscopy of a bulk sample of glass P0 (46.8 SiO2, 44.2 CaO, 9 CaF2; nominal composition in mol%) at 846°C.
The video shows a crystallisation sequence, illustrating the formation and growth of crystalline species in the internal volume (volume crystallisation). The sample was heated at 10 K/min and maintained at the first crystallisation temperature (846°C). An interesting phenomenon appears at approximately 90 min of treatment with two crystals growing radially to finally coalesce with other crystals to occupy the sample volume.