Multifunctional Pr3+-doped LiNaY2F8 phosphor for visible-to-UVC and X-ray-to-UVC conversion

Pr³⁺-doped LiNaY₂F₈ phosphors were synthesized and systematically investigated to evaluate their structural and luminescent properties under various excitation conditions. The material exhibits intense ultraviolet-C (UVC) emission around 250 nm attributed to 4f5d→4f transitions of Pr³⁺ ions. Upon blue-light excitation (~444 nm), efficient visible-to-UVC upconversion is achieved via a two-photon absorption process. Furthermore, strong UVC emission is observed under X-ray irradiation, demonstrating effective X-ray-to-UVC scintillation behavior. Detailed spectroscopic analysis reveals the excitation pathways and relaxation mechanisms governing the UVC emission. The demonstrated dual-mode excitation capability highlights LiNaY₂F₈:Pr³⁺ as a multifunctional phosphor with potential for applications in sterilization, radiation detection, and compact UVC light sources.