Synthesis And Properties Of A Novel High Stability Long Afterglow Phosphor

The long afterglow phenomenon has been observed by humans many years ago,but it has not been known and put into use until recently.Whether in the field of traditional lighting or high-tech,long afterglow materials have broad application prospects.In the field of vehicles,car dashboards and safety tips in low-light environments the long afterglow materials have many advantages.The long afterglow material is a kind of material that stores energy and releases it in the form of light energy.The traditional high-temperature solid phase method is relatively simple in preparation process.The material can be recycled,and most of them are composed of environmentally friendly materials.However,the common long afterglow materials can not meet with daily needs,stability,afterglow strength and other characteristics can not meet the requirements of use,on the other hand,the long afterglow mechanism is more complicated,and there is no unified theoretical explanation,which hindered the application.It is the promotation for us to develop new long afterglow materials to solve these problems.The research content of this paper can be divided into the following three aspects:?1?Developed a new long afterglow material Ga₄GeO₈:Ln,?Ln=Tb,Cr,Dy?with different afterglow colors,and discussed their optical properties.Among them,the long afterglow performance of Ga₄GeO₈:Tb is best.This novel green emitting long persistent luminescent phosphor Ga₄GeO₈:Tb³⁺was synthesized by high temperature solid-state method in air atmosphere.Undoped and terbium doped gallogermanate sample was characterized by X-ray diffraction?XRD?luminescence analysis and thermal analysis successively.Host emission and typical transitions of Tb³⁺ions were detected by PL spectra,indicated that there is energy transfer from host to Tb³⁺.Afterglow spectra showed green emission originate from ⁵D₄?⁷F_J?J=6,5,4,3?of Tb³⁺ions,corresponding to CIE chromaticity coordinates of x=0.3429,y=0.5454.The persistent luminescence decay curves revealed that Tb-doped sample have long duration time about 3-4 hour after remove the excitation source.The thermoluminescence results revealed that Tb³⁺sample possessed two main traps calculated to be 0.606eV and 0.732eV respectively.All the results showed that Ga₄GeO₈:Tb³⁺was a potential long persistent luminescence material.?2?A new yellow afterglow material BaSnGe₃O₉:xDy?x=0.5%,1%,2%,3%,5%?activated by Dy ion was prepared by high temperature solid phase method,and characterized by XRD,emission spectrum and afterglow spectroscopy.Its optical properties and afterglow properties were studied.Its emission spectrum and afterglow spectrum showed characteristic luminescence of Dy³⁺at 490nm,580nm and 680nm,corresponding to ⁴F_9/2-6H_15/2,⁴F_9/2-6H_13/2,⁴F_9/2-6H_11/2 transstions.The characteristic transition of the afterglow spectrum and the afterglow decay curve show that as the doping concentration increases,the rest of the glow intensity first increases and then decreases,And when x=2%is the optimal doping concentration,the sample has the best afterglow performance.The pyrolysis spectroscopy shows that the addition of Dy³⁺causes the sample to form multiple trap types,which increases the trap concentrations.Combined with the afterglow decay curve,it can be seen that the sample has a longer afterglow duration.?3?In the third part of this paper,the new long afterglow materials was developed for water resistance comparative with SrAl₂O₄:Eu.The strontium aluminate and the developed Ga₄GeO₈:Tb and BaSnGe₃O₉:Dy were immersed in the same environment for different times.The optical test and afterglow test were carried out on different samples.The results show that the new long afterglow material developed in this paper does not adhere after being immersed in water for more than ten hours,and the afterglow performance is hardly affected.It can be seen that its water resistance and stability are superior to SrAl₂O₄.