Synthesis And Fluorescent Properties Of Multi Color Phosphor For White LED

Since the beginning of twenty-first Century,with the depletion of natural resources and the increasingly prominent environmental pollution problems,semiconductor lighting equipment as a new means of lighting has aroused widespread interest.White LED lighting as an essential semiconductor lighting can replace the existing high-energy consumption of incandescent lighting.Moreover,phosphor as an important component of semiconductor lighting materials have attracted of great interest.Therefore,this paper focuses on the study of multi phosphors which can be excited by near ultraviolet chip.In this paper,YVO4:Sm3+,Eu3+ phosphors were prepared by sol-gel method.CaAl2Si2O8:Eu2+/Tb3+,BaMg2Al6Si9O30:Ce3+,Tb3+/Mn2+ multicolor phosphor samples were prepared by high temperature solid-state method.Scanning electron microscopy(SEM),X-ray diffraction(XRD),Fourier Transform Infrared(FT-IR)and fluorescence spectrophotometer are uesd to characterize the structure,shape,spectral analysis.The main points are as follows:(1)The phosphors YVO4:0.05Sm3+,xEu3+ were prepared by sol-gel method.Moreover,particles were uniform and the particle size was 500-600 nm.The YVO4:0.05Sm3+,xEu3+ phosphors have strong and wide excitation peaks in the 280-320 nm.Through Co-doped the Sm3,and Eu3+,the fluorescent intensity ratio is increased by 75%than single doped Eu3+.The critical distance of Sm3+and Eu3+ in YVO4 host is 10.28 A.The energy transfer mechanism is quadrupole-quadrupole interaction.By increasing the doping amount of Eu3+,the color of YVO4:0.05Sm3+,xEu3+ phosphors regularly changed from orange to red,The Commission International deL'Eclairage value of YVO4:0.05Sm3+,0.11Eu3+ enabled the achievement of the standard red coordinates(2)CaAl2Si2O8:Eu2+/Tb3+ phosphor system can be obtained by high temperature solid-state method.Fluorescence analysis of CaAl2Si2O8:xEu2+samples,under the excitation of 352 nm,a strong and broad emission peak from 400-600 nm can be obtained,and the emission peak is 444 nm,Under the condition of 444 nm,there is a strong and broad excitation peak between 220-400 nm.The quenching concentration of CaAl2Si2O8:xEu2+ is 0.03,the energy transfer mechanism is dipole-dipole interaction.In CaAl2Si2O8:0.03Eu2+,xTb3+ system,under the excitation of 352 nm,characteristic emission peaks including Eu2+ and Tb3+,and concentration quenching of the samples is 0.10,critical radius of Eu2+ and Tb3+ is 19.71 A.According detected the fluorescence lifetime,the average fluorescence lifetime can be calculated from 128.14 ns to 52.94 ns,and the fluorescence transfer efficiency is increased from 16.9%to 50.36%.CaAl2Si2O8:0.01Eu2+ phosphor can be used in W-LEDs.In CaAl2Si2O8:0.03Eu2+,xTb3+ phosphor system,with the increase of Tb3+,the fluorescent powder system can be changed from blue to blue-green.(3)Ba2Mg2Al6Si9O30(BMAS):Ce3+,Tb3+/Mn2+ phosphor powder synthesized by high temperature solid state method.The excitation spectra of BMAS:Ce3+ and Tb3+ phosphors show a strong and broad absorption band,and the excitation peak range is 220-380 nm.Under the excitation of 350 nm,the characteristic emission peak at 544 nm of Tb3+ and characteristic emission peak at 420 nm of Ce3+ can be observed.Critical radius of Ce3+ and Tb3+ is 18.62 A.When the concentration of Ce3+ increased from 0.01 to 0.13,the energy transfer efficiency increased from 3.26%to 76.59%.BMAS:0.05Ce3+,0.05Mn2+ can be observed under 315 nm light emission characteristics of Ce3+ and Mn2+ peak,indicating that the energy transfer between Ce3+ to Mn2+.Adjusting the ratio of Ce3+ to Tb3+ can make the emission peak of the sample change from blue to green.