Eu ²⁺ Doping Driven Polymorphic Transition in Sr ₂ SiO ₄ Glass Ceramic for Optical Property Tailoring and Multifunctional Photonic Applications

Abstract Polycrystalline phase transition provides an effective method to modulate structure of luminescent materials, offering a promising pathway for expanding optical properties and adaptive optoelectronic applications. In this study, for the first time the controlled β → ɑ phase‐transition engineering is reported in Sr ₂ SiO ₄ :Eu ^{2 +} glass ceramic (GC) through chemical doping of Eu ^{2 +} ions, where the Eu ^{2 +} ions act dual‐functionally as structural modulator and stabilizer. Molecular dynamics simulations reveal that Eu ² ⁺ doping does not significantly modify the short‐range order of glass, indicating that the β → α phase transition primarily results from dopant‐induced crystallization dynamics. Interestingly, the α ‐phase variant demonstrates thermochromic properties, enabling fluorescent anti‐counterfeiting applications; while the β ‐phase variant shows superior thermal stability (82% photoluminescence remained at 423 K), excellent water‐resistance, and extraordinarily stable color emission, making it suitable for high‐quality lighting with color rendering index up to 95. This work provides a new thought of designing a GC platform via controllable polymorphic phase transition toward multifunctional photonic applications.