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

In the pursuit of novel bactericidal solutions, there has been a significant advancement in the development of phosphors emitting ultraviolet C (UVC) radiation, intending to supplant mercury lamps in healthcare settings. Moreover, these innovative phosphors hold promise for treating X-ray-resistant tumors and disinfecting water in regions with limited access to electricity. In this study, a new UVC emitter, LiNaY 2 F 8 , doped with Pr 3+ ions, is introduced. The paper comprehensively examines the structural and optical properties of the material, utilizing visible (Vis), vacuum ultraviolet (VUV), and X-ray spectroscopy techniques. The presence of distinct crystallographic sites for Pr 3+ ions is demonstrated, and a potential mechanism is proposed for the simultaneous emission from the 4f 1 5d 1 and 1 S 0 levels of Pr 3+ . Furthermore, successful Vis-to-UVC upconversion in this host material is reported. UVC emission at approximately 250 nm was observed under 444 nm laser excitation. The power dependence analysis revealed that two photons of blue light are required to observe the upconversion. Additionally, the decay kinetics analysis of the upconversion luminescence suggests excited state absorption (ESA) as the most plausible mechanism for the upconversion process. Finally, the scintillating properties of the material are confirmed, with both UVC and visible luminescence detected upon X-ray excitation. This study introduces the newly synthesized luminophore, highlights its favorable optical characteristics for converting visible light or X-ray radiation into UVC, and emphasizes its potential multifunctional applications. A new UVC emitter, LiNaY 2 F 8 doped with Pr 3+ ions, is synthesized and studied for its optical properties, including UV spectroscopy. Successful Vis-to-UVC upconversion is achieved with a 444 nm CW laser, and the mechanism of this process is proposed. This work introduces the luminophore and its potential use in healthcare and X-ray therapy. • Two crystallographic sites of Y 3+ in LiNaY 2 F 8 affect luminescence behavior of Pr 3+ . • UVC luminescence varies with excitation wavelength, from 232 nm to 208 nm. • Anty-Stokes emission bands observed at 251, 261, and 274 nm under 444 nm excitation. • ESA mechanism proposed for Vis-to-UVC upconversion in LiNaY 2 F 8 ;Pr 3+ . • LiNaY 2 F 8 : Pr 3+ shows potential for scintillation in X-ray therapy and bioimaging.