Controlled Synthesis of Cs2NaYF6: Tb Nanoparticles for High-Resolution X-Ray Imaging and Molecular Detection

Rare-earth-doped fluoride nanoparticles (NPs), known for their tunable luminescence and high chemical stability, hold significant potential for applications in X-ray imaging and radiation dose monitoring. However, most research has primarily focused on lanthanide-doped NaLuF₄ or NaYF₄ nanosystems. In this work, Cs₂NaYF₆:Tb NPs with enhanced X-ray excited optical luminescence (XEOL) intensity were developed. Our results indicate that low oleic acid (OA) content and a high [Cs⁺]/[Na⁺] ratio favor the formation of pure cubic-phase Cs₂NaYF₆:Tb NPs. Cs₂NaYF₆:Tb NPs were successfully fabricated into thin films and employed as nanoscintillator screens for X-ray imaging, achieving a high spatial resolution of 20.0 Lp/mm. Beyond X-ray imaging applications, Cs₂NaYF₆:Tb NPs were also explored for spermine detection, demonstrating high sensitivity with a detection limit of 0.44 μM (under X-ray excitation) within a concentration range of 0-60 μM. These findings may contribute to the development of novel lanthanide-doped fluoride nanoscintillators for high-performance X-ray imaging and molecular sensing.