A new perspective for nucleation and nanocrystallization from interfacial energy and nanoscale composition fluctuations in glasses

Nucleation behaviors in glasses/supercooled liquids (SCLs) such as lithium disilicate Li₂O–2SiO₂, cordierite Mg₂Al₄Si₅O₁₈, fresnoite Ba₂TiSi₂O₈, and K₂O–Nb₂O₅–GeO₂/TeO₂ glasses were analyzed and discussed from the interfacial energy γ at SCL–nucleus interfaces and nanoscale composition fluctuations. Based on the fragility concept for SCLs and the intrinsic origin of γ, the magnitude order of γ(fragile SCL) < γ(strong SCL) was proposed to be a crucial guide for an understanding of high homogeneous nucleation rates and prominent nanocrystallization. The role of nucleating agent TiO₂/ZrO₂ in accelerating the nucleation rate in cordierite-based and β-spodumene-type Li₂O–Al₂O₃–SiO₂-based glasses was discussed from the new perspective of γ(homoepitaxial-like nucleation) < γ(heteroepitaxial-like nucleation). Ferroelectric nanocrystals such as Sr_xBa_1–xNb₂O₆ in borate glasses and fluoride nanocrystals such as CaF₂ are also well understood from the proposed guidelines. The present article provides a new perspective for nucleation in glasses/SCLs, contributing to the comprehensive composition design of new innovative glass-ceramics.