Luminescent Properties And Energy Transfer Of Rare Earth Doped Aluminosilicate Oxyfluoride Glass

As the fourth-generation solid-state lighting source,white LED have attracted much attention due to their many excellent characteristics such as high luminescent efficiency,energy saving and environmental protection,long lifetime,and good thermal stability.At present,a mainstream solution for implementing white LED is to couple a single-phase yellow phosphor with a blue chip.Compared to phosphors,fluorescent glass has many unique advantages,such as low preparation cost,no epoxy resin assembly process,good thermal stability,high humidity resistance,and so on.Among many fluorescent glass materials,oxyfluoride aluminosilicate glass processes the low phonon energy,low probability of no radiation relaxation,high luminous efficiency from fluoride glass,and high doped ion concentration from oxide glass.In this paper we choose aluminosilicate oxyfluoride glass as the matrix material.By doping appropriate rare earth ions and changing the doping concentration,high-quality white luminescent glass samples were successfully obtained,and the energy transfer process between the light-emitting ions was systematically studied:1.Eu²⁺/Tb³⁺/Eu³⁺doped aluminosilicate oxyfluoride glass:A series of Eu²⁺/Tb³⁺/Eu³⁺co-doped oxyfluoride aluminosilicate glass samples were synthesized by using the melt-quenching method in air atmosphere.X-ray diffraction patterns,X-ray photoelectron spectroscopy,Transmission spectra,excitation and emission spectra,decay curves and temperature-dependent emission spectra were utilized to investigate their structure and luminescent properties systematically.Under near-ultraviolet excitation,adjustable white light emission is generated as a result of efficient energy transfer from Eu²⁺to Tb³⁺and from Tb³⁺to Eu³⁺.Furthermore,the Eu²⁺/Tb³⁺/Eu³⁺co-doped glass presents good thermal stability.At 423 K,the emission intensity of the optimal G-5Tb4Eu glass remains about 86%of its initial intensity at298 K.These excellent properties indicate that Eu²⁺/Tb³⁺/Eu³⁺co-doped oxyfluoride aluminosilicate glass may provide a new platform for designing and fabricating white LED devices in the future.2.Eu²⁺/Eu³⁺/Tb³⁺/Al co-doped aluminosilicate oxyfluoride glass:In this paper,Eu²⁺/Eu³⁺/Tb³⁺/Al co-doped aluminosilicate oxyfluoride glass samples were synthesized via melt-quenching method in air atmosphere.Their structural and optical properties were systematically investigated through X-ray diffraction patterns,X-ray photoelectron spectroscopy,absorption spectra and photoluminescent spectra.The proportion of Eu²⁺and Eu³⁺can be controlled effectively by using various amounts of Al powder,which results in an adjustable luminescence in the glass samples.By combining the orange-red emission of Eu³⁺and blue broad emission of Eu²⁺as well as green emission of Tb³⁺,a white light emission with quantum yields of 30.0%was generated.At 513 K,the emission intensity of the optimal G-0.5Eu0.2Al4Tb glass remains about 93.1%of its initial intensity at 303 K.Our research exhibits the potential application of Eu²⁺/Eu³⁺/Tb³⁺/Al co-doped aluminosilicate oxyfluoride glass samples in white light-emitting diode devices.