Crystallization Kinetics of LAS Glass‐Ceramics With an SnO 2 –TiO 2 –ZrO 2 Nucleating System by In Situ Microscopy

ABSTRACT Precise control of crystallization kinetics is crucial for tailoring the microstructure and properties of transparent Li 2 O–Al 2 O 3 –SiO 2 (LAS) glass‐ceramics. In this work, the crystallization behavior of LAS glasses was systematically investigated by progressively replacing TiO 2 with SnO 2 within a standard Ti–Zr system, maintaining a constant total nucleating agent content. By integrating in situ spectroscopy with hot‐stage microscopy, real‐time time‐temperature‐transformation (TTT) curves were constructed, enabling precise characterization of crystallization kinetics and overcoming the limitations of conventional “black‐box” thermal analysis. Structurally, Raman spectroscopy revealed that SnO 2 substitution drives network repolymerization, transitioning from Q 2 to Q 3 /Q 4 species. To overcome the kinetic hindrance of this rigidified network, a thermodynamic‐kinetic dual synergy governed by the Sn 4+ /Sn 2+ equilibrium is activated. Thermodynamically, Sn 4+ expands the precursor lattice to lower nucleation barriers, while kinetically, Sn 2 + acts as a local modifier to enhance atomic mobility. Consequently, the optimized composition (1.5 mol% SnO 2 ) exhibits the most favorable kinetics, with the induction period shortened to 107 s and the onset temperature lowered by 50°C compared to the Sn‐free reference. This optimal synergy promotes intense site‐saturated nucleation, significantly refining the quartz solid solution crystallites from 68 to 30 nm. Ultimately, guided by these elucidated mechanisms, an optimized heat treatment regimen was established, providing an effective pathway for preparing high‐performance nanostructured glass‐ceramics.