Continuous compositional changes of crystal and liquid during crystallization of a sodium calcium silicate glass

This paper deals with a systematic study of crystal nucleation and growth kinetics in a 14.6Na2O–34.0CaO–51.4SiO2 mol% glass, which is close to the CaO · SiO2–Na2O · SiO2 pseudo-binary section, just left of the stoichiometric Na2O · 2CaO · 3SiO2 (N1C2S3) compound. We show that crystallization begins with nucleation of a Na4+2xCa4−x[Si6O18] (0 < x < 1) solid solution that is enriched in sodium as compared with both parent glass and the N1C2S3 compound; while a fully crystallized sample is composed only by a solid solution that is stable at very high temperatures, but is metastable in the temperatures under investigation. We thus confirm a continuous compositional change of the crystals during the course of crystallization.