Solid-State Synthesis And Luminescence Properties Of Lanthanide Doped NaREF₄?Re=Gd,Y,Lu?

Lanthanide doped luminescent materials have unique optical properties,so they have practical applications in such as planar display luminescent devices,biomarkers and imaging,and enhanced solar cells.In particular,inorganic fluoride has attracted much attention due to its low phonon energy and well chemical stability.In this paper,tetrafluoride was used as host material,and fluoride with different morphologies was obtained by solid-state reaction at medium temperature.NaREF4:xLn3+(RE=Gd,Y,Lu;Ln3+=Dy3+,Tb3+,Eu3+)series of various phosphors with excellent luminous effect X-ray powder diffractometer(XRD),scanning electron microscope(SEM),fluorescence spectrum and other instruments(PL)were used to study the phase structure,morphology,size and luminescence performance of phosphors.The following is the main work of the paper:1.NaREF4:xLn3+(RE-Gd,Y,Lu;Ln3+=Dy3+,Tb3+,Eu3+)phosphors were successfully prepared by solid-state reaction at 100-300? for 5-10 h.A half of the obtained samples were annealed at 400-500?.XRD results showed that annealing process can make diffraction peak of the sample were sharper and better crystallized.PL results showed that the characteristic transitions of NaREF4:xDy3+is 4F9/2?6H15/2(478 nm),the characteristic transitions of NaREF4:xTb3+is 5D4?7F5(543 nm),the characteristic transitions of NaREF4:xEu3+is 5D0?7F1(591 nm).In most cases,Annealing can improve the emission strength of the sample.2.NaGdF4:xEu3+series samples after annealing treatment at 500?,when the doping concentration of Eu3+is relatively low,the Eu3+can be transmitted not only from the lower 5D0 energy level,but also from the higher excited states 5D1,2,3.The energy transfer between Gd3+,Dy3+,Tb3+,and Eu3+was investigated.Therefor,a series of co-doped and tri-doped phosphors were prepared.Such as NaGdF4:0.O5Dy3+,xTb3+,NaGdF4:0.07Tb3+,xEu3+,NaGdF4:0.04Dy3+,0.04Tb3+,xEu3+.As the concentration of Eu3+increases,the luminescence color of NaGdF4:0.07Tb3+,xEu3+samples were tendency from green,yellow,to orange-red.The luminescence color of NaGdF4:0.04Dy3+,0.04Tb3+,xEu3+series samples were tendency from blue-green,green,to orange-red.3.PL results showed that under the excitation of 350 nm,NaREF4:0.05Dy3+,xTb3+(RE=Y,Lu)series of samples exist both Dy3+and Tb3+characteristic emission.In this work,NaYF4:0.05Dy3+,0.05Tb3+,xEu3+were successfully prepared by solid-state reaction at medium temperature.In order to achieve the common emission of Dy3+,Tb3+and Eu3+ions.4.The chromaticity coordinates of NaREF4:xLn3+(RE=Gd,Y,Lu;Ln3+=Dy3+,Tb3+,Eu3+)show that CIE chromaticity diagram is related to host materials,doping concentration of lanthanide ions,and annealing.Annealing has little effect.Dy3+ions in tri-doped samples,Dy3+transfer energy to Tb3+ions,and Tb3+ions transfer energy to Eu3+ions to realize the co-emission of multiple ions.multicolor-tunable luminescence phosphors can be obtained by changing the concentration of doped ions and annealing.