Ca²⁺/Sr²⁺/Ba²⁺ dependent phase separation, nanocrystallization and photoluminescence in fluoroaluminosilicate glass

Fluoride phase separation is the initial stage of nanocrystallization in oxyfluoride glasses, and it is a key step in achieving transparent glass-ceramics with good luminescence. In this work, we combine molecular dynamics (MD) simulations and experimental studies to investigate the phase separation, nanocrystallization and photoluminescence in fluoroaluminosilicate glass and glass-ceramics containing alkali earth fluoride (MF₂). The results reveal different phase separation behaviors due to the field strength difference of M²⁺. The composition and size similarity between the fluoride-rich regions in the MD simulated glass and the fluoride nanocrystals in the experimental prepared glass-ceramics are observed, suggesting that the separated fluoride phase is the structural origin of the observed MF₂ nanocrystals. Besides, in order to understand the M²⁺ dependent glass structural features, the crystallization temperatures, the luminescent properties of Eu³⁺ and Eu²⁺ doped glass-ceramics, and the lasing performance of Er³⁺ doped glass-ceramics are discussed. Based on these comprehensions, some strategies are proposed to help to efficiently design oxyfluoride glass with desired luminescence performance.