Study On Synthesis And Performance Of Cerium Ions Luminescent Materials In Ionic Liquid Systems

In this paper,the synthesis and luminescence properties of rare earth soft luminescent materials in the ionic liquid[Bmim][Br]?1-butyl-3-methylimidazolium bromide?system were studied by combining ionic liquids with rare earth halides and using rare earth Ce³⁺ions as the luminescent center.Based on the ionic liquid system,the effects of different ionic liquids with different carbon chain lengths on the synthesis and luminescence properties of rare earth soft luminescent materials were studied.The luminescent properties of rare earth complexes in mixed ionic liquid systems were also studied.The research work was mainly carried out from the following two parts:Part 1.The synthesis of Ce:[Bmim][LaBr₄]/[Bmim][Br].We use bromide ionic liquid[Bmim][Br]and barium bromide as matrix,dope rare earth cerium ions to obtain rare earth complexes,and then use[Bmim][Br]as solvent to dissolve rare earth complexes into the ionic liquid.Thereby,a transparent rare earth luminescent soft material Ce:[Bmim][LaBr₄]/[Bmim][Br]is obtained.The effects of temperature,raw material ratio and other factors on the synthesis of rare earth complex Ce:[Bmim][LaBr4]were investigated.Through optical performance test,the results indicate:when it excited by 320 nm ultraviolet light,there are two emission peaks in the range of350-450 nm,which positions are located at 377 nm and 406 nm,respectively.The photoluminescence decay times are 10 ns and 31 ns,and the X-ray excitation has a broad emission spectrum.We suspect that the ionic environment in the liquid soft material is more complex,making the ²F_5/2 and ²F_7/2 energy levels discrete.In the mixed solvent[Bmim][Br]and[Omim][Tf₂N],the luminescence intensity of Ce:[Bmim][LaBr₄]/[Bmim][Br]is enhanced.Part 2.The synthesis of Ce:[Emim][LaBr₄]/[Emim][Br]and Ce:[Omim][LaBr₄]/[Omim][Br]?[Emim][Br]=1-ethyl-3-methylimidazolebromine,[Omim][Br]=1-octyl-3-methylimidazolium bromide?.We selected ionic liquids[Emim][Br]and[Omim][Br]as reaction systems to obtain rare earth complexes Ce:[Emim][LaBr4]and Ce:[Omim][LaBr4].Then,we use the ionic liquids[Emim][Br]and[Omim][Br]as solvents to dissolve the rare earth complex into its own ionic liquid to obtain a uniform transparent rare earth soft luminescent material Ce:[Emim][LaBr₄]/[Emim][Br]and Ce:[Omim][LaBr₄]/[Omim][Br].The photoluminescence spectrum,photoinduced decay time spectrum and X-ray excitation emission spectrum of the two samples were tested at room temperature and analyzed.?1?The results of Ce:[Emim][LaBr₄]/[Emim][Br]show that two emission peaks at 377 nm and 408 nm are obtained under ultraviolet excitation of 320 nm,which is a blue-violet light-emitting band.With 400 nm as the monitoring wavelength,there are two excitation peaks at332 nm and 365 nm.The photoattenuation time is 29.12 ns.Under X-ray excitation,there is a broad emission peak in the range of 350-450 nm with a peak at 400 nm.?2?The results of Ce:[Omim][LaBr₄]/[Omim][Br]show that the photoluminescence spectrum of the samples at various ratios can be obtained under the excitation of 320 nm ultraviolet light.The effect of the ratio of reactants on the luminescence intensity has certain regularity.However,due to the uncontrollable moisture in the system,the effect of the ratio of reactants on the luminescence intensity needs further study.According to the double exponential fitting results,the decay time is 4.96 ns and 18.28 ns,and the decay time of Ce:[Omim][LaBr4]/[Omim][Br]is the shortest among the three rare earth luminescent soft materials.So,its luminescence performance is also the best.Under X-ray excitation,there is a broad emission peak in the 350-450 nm range.Under the action of the mixed solvents[Omim][Br]and[Omim][Tf₂N],the luminescence intensity of Ce:[Omim][LaBr₄]/[Omim][Br]is enhanced.