Improvement of quantum efficiency through Gd³⁺ to Eu³⁺ energy transfer in YF₃ phosphor

This paper reports the energy transfer from Gd³⁺ to Eu³⁺ in YF₃ and the consequent downconversion luminescence for the YF₃ :Gd³⁺ , Eu³⁺ fluoride phosphor. The phosphor was synthesized using a soft chemical route, followed by a reactive atmosphere process. Because of the wide band gap in YF₃ and the correct energy site for ⁸ S_7/2 -⁶ G_J transitions of Gd³⁺ ions, fluoride YF₃ doped with Gd³⁺ -Eu³⁺ were studied in their vacuum-ultraviolet (VUV) spectral regions. Powder X-ray diffraction (XRD) analysis showed the structural purity of YF₃ . VUV excitation and emission properties were explored using a VUV synchrotron radiation beam line. Downconversion of energy from VUV (157 nm) to visible light with quantum efficiency c. 189% was seen. This YF₃ :Gd³⁺ , Eu³⁺ phosphor would be an option for mercury-free fluorescence lamps.