Preparation And Luminescence Properties Of ABCO₄:Re³⁺（Re=Eu,Dy） Phosphors

Rare earth elements have spectral properties that most other elements cannot match,and rare earth compounds have extremely excellent performance in the three major fields of optical,electrical and magnetic.China’s rare earth resources rank first in the world,but there is still a big gap between the application and scientific research of rare earth materials and the world’s advanced level.In recent years,rare earth luminescent materials have been widely used in lighting,display,anti-counterfeiting,fluorescence detection and other fields,so it is of great significance to vigorously develop the application and research of rare earth materials.At present,the main implementation of the new generation of lighting source white LED is to use blue LED chip composite rare earth luminescent material(YAG:Ce³⁺)or ultraviolet LED chip to excite three primary color phosphors（rare earth luminescent materials）.Therefore,rare earth luminescent materials play a pivotal role in the application of lighting sources,and several rare earth luminescent materials of different systems are prepared by high-temperature solid phase method,and their luminescence properties are studied,and their application in white LEDs is developed.（1）Preparation and luminescence performance of SrLa Ga O₄:Dy³⁺white luminescent phosphorA series of SrLa_1-xGa O₄:x Dy³⁺（x=0.01～0.07）white luminescent phosphors were successfully prepared by the high-temperature solid phase method.The phase and morphology tests of the sample powder were analyzed by XRD and SEM,and the XRD test results showed that the phase purity and the least heterogeneous phase of the synthetic sample of Dy³⁺single-doped matrix SrLa Ga O₄phosphor were the highest phase purity and the least heterogeneous phase under the condition of calcination at1300-1400°C for 4 h.The SEM test results show that the sample particles have good crystallinity,their shape is irregular,and the particle size diameter is from 1μm to 30μm.The excitation-emission spectroscopy test analysis of the phosphor by F-4700fluorescence spectrophotometer showed that the phosphor could be effectively excited by near-ultraviolet light（353 nm）to produce two strong emitted lights located at 484nm（blue light）and 580 nm（yellow light）.The emitted light at 484 nm comes from the magnetic dipole transition of Dy³⁺(⁴F_9/2→⁶H_15/2),and the emitted light at 580 nm comes from the electric dipole transition(⁴F_9/2→⁶H_13/2).The average lifetime of the two emitted lights is 0.340 ms and 0.341 ms,respectively.Through the combination of yellow light and blue light,a luminescent effect of white light is finally produced,and the color coordinates are around（0.362,0.368）.The phosphor can have a relatively good white light luminescence effect under near-ultraviolet excitation.（2）Study on the preparation and luminescence performance of SrLa Al O₄:Re³⁺（Re=Dy,Eu）phosphorsA series of SrLa_1-xAl O₄:x Dy³⁺（x=0.01～0.07）white luminescent phosphors,SrLa Al O₄:Eu³⁺red luminescent phosphors and a series of SrLa_0.97-xAl O₄:0.03Dy³⁺,x Eu³⁺（x=0.005～0.04）white luminescent phosphors doped with Dy³⁺and Eu³⁺were successfully prepared by high-temperature solid phase method.XRD and SEM were used to test and analyze the phase and morphology of the sample powder,and the XRD test results showed that whether it was Dy³⁺single-doped SrLa Ga O₄phosphor or Dy³⁺and Eu³⁺co-doped SrLa Ga O₄phosphor,the samples synthesized under the condition of calcination at 1450°C for 4 h had high phase purity and relatively few heterogeneous phases.The SEM test results show that whether it is Dy³⁺single-doped SrLa Al O₄phosphor or Dy³⁺and Eu³⁺co-doped SrLa Al O₄phosphor,the sample is made of some irregular particles,the particle size is directly about 1μm to 5μm,the shape of a single fine particle is irregular and the size is different,but the surface is relatively smooth and has good crystallinity.The excitation-emission spectrum and fluorescence lifetime test analysis of these three phosphors by F-4700 fluorescence spectrophotometer showed that SrLa Al O₄:Dy³⁺phosphors could be effectively excited by near-ultraviolet light（354 nm）to produce two strong emitted rays at 483 nm（blue light）and 579 nm（yellow light）,with average lifetimes of 0.380 ms and 0.382 ms,respectively.And the blue light emission intensity at 483 nm is very different from the yellow light emission intensity at 579 nm,so there will be a luminescence effect of white light with a color coordinate of（0.346,0.359）,which is very close to the standard white light color coordinates（0.333,0.333）.SrLa Al O₄:Eu³⁺phosphor has a strong and wide excitation band and six obvious narrowband characteristic absorption peaks in the UV-Vis（230 nm～500 nm）range under the irradiation of the monitoring wavelength of 622 nm.And the phosphor can be excited by near-ultraviolet light,producing a red light emission.Double-doped SrLa Al O₄:Dy³⁺,Eu³⁺phosphors can not only show the characteristic excitation spectra of Dy³⁺single-doped SrLa Al O₄at the monitoring wavelength of 579 nm,but also the characteristic excitation spectra of Eu³⁺single-doped SrLa Al O₄at the monitoring wavelength of 622 nm.The emission spectrum of the phosphor shows the characteristic emission peak of Dy³⁺and the characteristic emission peak of Eu³⁺under the same excitation light,and according to the different excitation light,the phosphor can produce a red light and white light conversion effect.By studying the fluorescence lifetime of Dy³⁺at 483 nm(⁴F_9/2→⁶H_15/2)in phosphors with different Dy³⁺/Eu³⁺doping concentrations,energy transfer between Dy³⁺and Eu³⁺in SrLa Al O₄:Dy³⁺,Eu³⁺phosphors was demonstrated.（3）Preparation and luminescence performance of SrLa Al₃O₇:Dy³⁺white luminescent phosphorA series of SrLa_1-xAl₃O₇:x Dy³⁺（x=0.01～0.08）white luminescent phosphors were successfully prepared by the high-temperature solid phase method.The structure morphology and luminescence characteristics were tested and analyzed by powder X-ray diffractometer（XRD）,field emission scanning electron microscopy（SEM）and fluorescence spectrophotometer.The results showed that the phase purity of phosphor was the best at 900°C.The sample powder particles were blocky,the surface showed a hollow structure,the mesh diameter was about 25 nm,and the surface was relatively smooth,and the particles were evenly arranged.The phosphor can be efficiently excited by near-ultraviolet light（347 nm）to produce two strong emission spectra at478 nm（blue light）and 577 nm（yellow light）with color coordinates around（0.34,0.36）.