Evolution of crystal growth in MgO–Al2O3–SiO2 glass ceramics
It is a necessary part of crystal design to explore the process through which crystals precipitate in glass ceramics. In this work, transmission electron microscopy (TEM) was used to structurally characterize a glass of composition 20MgO–20Al2O3–54SiO2–3K2O–1Fe2O3–2TiO2 (mol%). The evolution of the glass–crystal interface during the crystallization process was investigated using energy dispersive X-ray spectrometry (EDXS) in scanning transmission electron microscopy (STEM) mode. Results showed that alkaline-earth metal Mg aggregated at the interface during crystallization to form an Mg-enriched layer, which could be verified through the concentration formula. According to the results of molecular dynamics (MD) simulation, the difference in diffusion coefficients between the base glass and Mg-enriched layer leads to the formation and stabilization of the layer. MD simulation also indicated that there was aggregation of Al in the enriched layer, which inhibited further crystal growth.