Font Size: a A A

Synthesis And Luminescence Properties Of Rare Earth Doped Tungsten-molybdenum Luminescent Materials

Posted on:2019-09-25Degree:MasterType:Thesis
Country:ChinaCandidate:X Y QiuFull Text:PDF
GTID:2371330548451822Subject:Inorganic Chemistry
Abstract/Summary:PDF Full Text Request
In this paper,a series of luminescent materials doped with different rare earth elements and based on F-doped tungstate or tungstate were prepared by high temperature solid phase method.The crystal structure,excitation spectrum,emission spectrum,lifetime,pyroelectric properties and color coordinates of the samples were characterized by XRD and fluorometer.The crystal structure,excitation and emission spectra of phosphor prepared under different conditions were measured by changing the concentration of rare-earth doped ions,the structure of matrix and the type of rare-earth doped ions,to seek the optimize the luminous performance and the best conditions of phosphor.(1)A series of red luminescent powder NaGdi-x(MoO4)(WO4):xEu3+ with stable and good luminescent molybdate system were prepared by high-temperature solid-state reaction method and characterized by means of fluorescence spectrometer and X-ray diffraction(XRD).Means to study the structure and luminescence properties of the sample.It belongs to the tetragonal crystal structure and its spatial point group structure is I41/a88.Comparing the luminescence properties of all prepared samples,it was found that when x=0.10,the fluorescence emission performance of NaGdi-x(MoO4)(WO4):xEu3+ was the best.At the monitoring wavelength of 616 nm,the excitation spectrum has a strong excitation peak at 395 nm and 466 nm,respectively,which should be the transition between 7F0?5L6 and 7F0?5D2 of Eu3+.And analyzed the sample's pyrolytic properties,life and color coordinates.(2)The NaBii-x(MoO4)(WO4):xEu3+ red phosphor for white LEDs was prepared by high temperature solid-state method.This article describes the calcination process at 800 ? for 4h,doped with Eu3+sodium bismuth molybdate.The red fluorescent powder samples were characterized and analyzed by fluorescence spectrometer.The results showed that the sample particles had well morphology and uniform size;the sample was excited with near-ultraviolet light at 466 nm,and the main emission peak was located at 616 nm.The luminescence intensity increases with the increase of Eu3+ doping amount.When the Eu3+ doping amount x=0.08,the luminescence is the strongest,and then the concentration quenching phenomenon occurs with the increase of the Eu3+ doping.(3)A series of NaGd(WMo)O8-x/2Fx:Eu3+phosphors were prepared via a high temperature solid state reaction in air atmosphere and their crystal structure and luminescence properties were investigated by X-ray Diffraction(XRD)and fluorescence spectrophotometer.The results indicate that these phosphors belongs to scheelite tetragonal crystal structure with a space group of I41/a.These phosphors can be excited efficiently by near-ultraviolet(395nm),and the main emission peak is located at 616 nm,which is ascribed to5D0?F2transition of Eu3+ ions.The optimum doping concentration of F-ions in NaGd(WMo)O8-x/2Fx:Eu3+ is 0.2.The luminescence intensity of NaGd(WMo)O7.9F0.2:0.10Eu3+is increased by 41%in comparison with NaGd(WMo)O8:0.10Eu3+,and it chromaticity coordinate is(0.653,0.336).(4)A series of phosphors NaGd1-x(MoO4)(WO4):xSm3+(x=0.01,x=0.02,x=0.03,x=0.04,x=0.05 and x=0.06)were prepared by a high temperature solid state reaction in air atmosphere.X-ray diffraction,photoluminescence(PL)spectra and lifetime analysis were utilized to characterize the synthesized phosphors.These phosphors possessed scheelite tetragonal crystal structure with a space group of I41/a.Upon excitation at 406 nm,the emission peaks at 564 nm(4G5/2?6H5/2),600 nm(4G5/2?6H7/2),646 nm(4G5/2?6H9/2)and 700 nm(4G5/2?6H11/2)transitions of Sm3+ were observed.The optimum doping concentr ation of Sm3+ ions in NaGd(MoO4)(WO4)was at 3.0 mol%.The energy transfer mechanism between the Sm3+ ions was confirmed as dipole-dipole interaction and the critical distance was obtained to be 21.59A.NaGd0.97(MoO4)(WO4):0.03Sm3+ phosphor performed good fluorescent thermal stability at 200?.These results indicated that NaGd1-x(MoO4)(WO4):xSm3+ phosphors as a potential candidate as high thermal stability phosphors solid-state lighting.
Keywords/Search Tags:red phosphor, tungsto-molybdate, solid state reaction method, fluorescence performance
PDF Full Text Request
Related items