Unusually Effective Blue-to-UVC Upconversion of Pr3+-Doped Sr3Lu(PO4)3 and Ba3Lu(PO4)3 Phosphors: A Comparative Study
Nadiia Rebrova, Alexander Grippa, Patrycja Zdeb-Stańczykowska, Przemysław J. Dereń
Abstract:
Many pathogens, including bacteria and viruses, are increasingly developing resistance to conventional disinfectants. As a result, new approaches to disinfection are being explored, such as the use luminophores that convert visible light into ultraviolet C radiation (UVC). In this work, we present novel UVC phosphors, A3Lu(PO4)3 (A = Sr, Ba), activated by Pr3+. These phosphates were synthesized by the Pechini method with different activator concentrations and crystallized in a cubic structure with the space group I4̅3d. The emission and excitation spectra, as well as decay times under synchrotron and visible-light excitation, were measured. Both phosphates exhibited efficient and fast 5d–4f emission from 240 to 340 nm, along with a very weak f-f emission line around 600 nm upon ultraviolet excitation. Multiphonon relaxation from the 3P0 to 1D2 state causes the phosphors to emit weak blue (3P1 → 3H4) and intense orange (1D2 → 3H4) light upon direct excitation of the 3P2 level. The upconversion properties of A3Lu(PO4)3:Pr3+ crystallites were investigated under 444 nm laser excitation, and the effect of Pr3+ concentration on these properties was evaluated. Compared to the YPO4:Pr3+ reference material studied earlier, the Ba3Lu(PO4)3:Pr3+ host showed a 20-fold enhancement in UVC upconversion emission, making this phosphate one of the most efficient visible-to-ultraviolet upconversion matrices to date. Thus, the studied phosphates have potential use in sterilization, disinfection, photocatalysis, and phototherapy.
More: https://doi.org/10.1021/acs.inorgchem.5c01458
