Molten Salt Synthesis of Single-Crystalline Sr₂MgSi₂O₇: Eu²⁺, Dy³⁺ Nanoplates: Breaking the Afterglow-Size Trade-off

Sr₂MgSi₂O₇/Eu²⁺, Dy³⁺ (SMSED) phosphors show promise for persistent luminescence applications due to their long afterglow and robust chemical stability. However, a trade-off exists between achieving precise size and shape control of SMSED and maintaining prolonged afterglow intensity and duration during synthesis. Herein, we unveil a molten-salt method that successfully produces uniform single-crystalline plate-like SMSED for the first time. This synthesis significantly reduces both the sintering temperature and time compared to the classic solid-state reaction (SSR) method. Owing to the nanoplates structure, uniform size distribution, and single-crystal nature, the resulting SMSED exhibited excellent afterglow performance and thermal stability, with a sustained blue afterglow exceeding 24 h and retaining >70% of its initial luminescence up to 523 K, outperforming most reported SMSED phosphors. These remarkable properties underscore the considerable potential of SMSED nanoplates for applications in fingerprint detection. This work unlocks a new synthetic frontier for achieving the controllable synthesis of SMSED phosphors, paving the way for future optimizations aimed at the development of advanced persistent luminescent phosphors.