Upconversion Luminescence Properties of Pr³⁺-Doped BaYF₅ Nanoparticles Prepared by Microwave Hydrothermal Method

Pure and Pr³⁺-doped BaYF₅ nanoparticles were synthesized by the microwave hydrothermal method. The nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and optical spectroscopy. The XRD and TEM confirm that the average size of nanoparticles is in the range of 26–37 nm. The optical excitation and luminescence spectra of BaYF₅:Pr³⁺ nanoparticles are presented in the visible and ultraviolet (UV) range. It has been verified that Pr³⁺ ions are capable of emitting UV-C photons when excited by a 444 nm laser. This emission arises from a two-photon energy-transfer upconversion mechanism. The concentration dependence of the upconversion luminescence of BaYF₅:Pr³⁺ was studied.