The Synthesis And Luminescent Properties Investigation Of Rare-earth Doped Nano-Phosphors

Along With the development of field emission(FED) and plasma light emitting display(PDP) technology,higher demands have been bring forward to phosphor particle size distribution,stability,light-emitting efficiency,brightness,as well as electrical conductivity.As for the nanophosphor materials quantum effect,surface effect,small-size effect and other excellent properties have great impact on their photoluminescence properties,which have come to be the research focus of the new nanophosphor materials.Among the many nanophosphor materials,ZnO has become to be a kind of promising optoelectronic applications and photosensor candidate materials due to its special optical performance;At the same time,the aluminoborate matrix also has good chemical stability and thermal stability, therefore the focus of this paper is to study the rare earth doped luminescent materials which use aluminoborate and ZnO as matrix.Along With the development of field emission(FED) and plasma light emitting display(PDP) technology,higher demands have been bring forward to phosphor particle size distribution,stability,light-emitting efficiency,brightness,as well as electrical conductivity.As for the quantum effect,surface effect,small-size effect and other excellent properties of the nanoluminescent materials have great impact on their photoluminescence properties;nanoluminescent materials have come to be the research focus of the new luminescent materials.Among the many nanoluminescent materials,ZnO has become to be a kind of promising optoelectronic applications and photosensor candidate materials due to its special optical performance;At the same time,the aluminoborate matrix also has good chemical stability and thermal stability,therefore the focus of this paper is to study the rare earth doped luminescent materials which use aluminoborate and ZnO as matrix.In this paper,the present status of nano luminescent materials are reviewed,lanthanide ion spectra theory and luminescence of lanthanide-doped nanoparticle research background are systematically introduced,summarized and reviewed the progress and the facing problems about lanthanide-doped luminescent nanoparticle synthesis and surface modification in recent years, and the future research directions are also summarized and prospects.On this basis,we aimed at the luminescent materials demands that requested by the Field Emission Display(FED) and plasma(PDP),regard rare earth doped aluminoborate and zinc oxide as research objects,a variety of rare earth doped nanocrystals that have different optic properties and morphologies have been successfully synthesized by sol-gel method,hydrothermal method, hot solvent method,vibration method etc..The impact of synthetic conditions and the doping ion concentrations on the rare earth doped nanocrystals crystal structure,morphology,size,doping ion solid solution and luminescent properties were studied by means of X-ray diffraction(XRD), field emission scanning electron microscope(SEM),photoluminescence spectroscopy(PL),energy dispersion spectroscopy(EDX),luminescence decay curves and life expectancy,a series of important conclusions and innovative results were acquired.Laid a solid foundation for the rare earth doped nanoluminescent material to be a new promising luminescent material. SrAl₂B₂O₇:Eu³⁺,SrLi_xAl₂B₂O₇:Eu_5%³⁺,SrNa_xAl₂B₂O₇:Eu_5%³⁺,SrAl₂B₂O₇:Tb³⁺,SrAl₂B₂O₇:Ce³⁺,Tb³⁺,YAl₃(BO₃)₄:Eu³⁺,Dy³⁺,YAl₃(BO₃)₄:Eu²⁺,Dy³⁺,YBO₃:Eu³⁺,RE and ZnO:Eu³⁺ luminescent systems were synthesized.Studied the impacts of rare earth quality,concentration,synthesis temperature and matrix composition on the luminescent properties.The experimental results showed that the YAl₃(BO₃)₄,YAl₃(BO₃)₄:Dy³⁺,Eu³⁺,YAl₃(BO₃)₄:Dy³⁺,Eu²⁺ samples are triangle crystal.The Al₃(BO₃)₄:Eu²⁺,Dy³⁺ characteristic spectrum comes from the f-d transition of Eu²⁺.The codoping of Dy³⁺ intensified the fluorescence intensity, and it also mished the samples decay time.The best doping concentration of Oy³⁺ is 1.25%The same method was used to synthesize cubic systems of SrAl₂B₂O₇ and SrAl₂B₂O₇:Eu³⁺,M(M=Li⁺,Na⁺),SrAl₂B₂O₇:Tb³⁺,SrAl₂B₂O₇:Ce³⁺,Tb³⁺.In the SrAl₂B₂O₇:Eu³⁺ system,the best doping concentration is 5%.In the Sr_0.96-xLi_xAl₂B₂O₇:Eu³⁺(5%) system,the best doping concentration of Li⁺ is 7%. In the Sr_0.96-xNa_xAl₂B₂O₇:Eu³⁺(4%) system,the strongest luminescent intensity was abtained when the 3%is chosen as the doping concentration of Na⁺.As for the SrAl₂B₂O₇:Tb³⁺ samples,the best doping concentration of Tb³⁺ is 5%. The codoping of Ce³⁺ greatly intensified the emission band intensity.The samples fluorescent lifetime is also intensified.The single phase vaterite Y_0.95-xBO₃:Eu_5%³⁺,Gd_x³⁺ was synthesized using sol-gel menthod at 900℃air condition for 4h.Along with the increase calcination temperature,the crystal growth and the crystal is integrity,the fluorescent intensity is also intensified.The Y_0.95-xBO₃:Eu_5%³⁺ fluorescent intensity is improved when the doping concentration of Gd is changed.The best doping concentration of Gd is 30%.YBO₃:Eu³⁺,M(M=Na⁺,Li⁺,Ca²⁺,Ba²⁺,Sr²⁺,Al³⁺ samples were synthesized.The impact of different kinds to the samples fluorenscent intensity is discussed.The results showed that the order of sample fluorescent intensity is as follows:Li⁺＞Na⁺＞Ca²⁺＞Al³⁺＞vacancy＞Sr²⁺＞Ba²⁺.The samples luminescent intensity has close relations with the radius. The smaller radius of the codoping ions is,the stronger fluorescent intensity is got.At the same time,when the raius of the doping ions is smaller than Eu³⁺,the Y_0.95BO₃:Eu_5%³⁺fluorescent intensity is intensified.But the Y_0.95BO₃:Eu_5%³⁺fluorescent intensity is weaken when bigger radius ions were doped,which radius is bigger than Eu³⁺.Rare earth doped ZnO phosphors were also studied.For one thing,a new method- concussive method was used to synthesize ZnO及ZnO:Eu³⁺ nanorodsw. The optimal concussive frequency and reaction time are 750t/s and 24h respectively.The average diameter and length of the nanorods are 80 nm and 2μm respectively.The composing process and reaction mechanism are analysed, and the luminescent characteristics were also studied.Zinc oxide nanorods and zinc oxide nanoflowers were synthesized by new mentods,the dimention of the prepared nanorods are uniform with a diameter of about 65-75nm and a length of about 1.5μm.Different morphologies of zinc oxide and rare earth doped zinc oxide were successfully prepared via sol-gel method,thermal solvent method and hydrothermal method.The relationship between the microstructure and macroscopic luminescent properties were studied for the first time.The reaults showed that fluorescent intensity orders of the samples with different morphologies are as follows:nanorod arrays＞nanoparticles membrane＞nanoparticels＞nanoflowers＞nanorods.There are close relation ship between the samples properties and the homogeneous degree.The biger the samples homogeneous are,the stronger the samples luminescent intensity is.There are also close relation ship between the samples luminescent properties and the size of the sample diameters.The bigger the samlples diameter is,the stronger the samples luminescent intensity is.The samples homogeneous degree plays the decisive position between the two qualities.When two samples homogeneous degree are similar with each other,their luminescent degree will decided by their diameters.