Preparation And Characterization Of YVO₄:bi³⁺,ln³⁺?ln=Eu,Dy,Sm? Luminescence Materials

LED were applied in various fields due to its advantages of environmental friendliness,lower power consumption,light weight,small size,high brightness,long life,stable performance.As a critical material of LED devices,the quality of phosphors directly determines the practical performance of LED.The rare earth ion doped vanadate phosphors have gained more and more attention due to it has a good chemical stability,crystal lattice stability,high temperature resistance,visible light transmittance,and strong absorption bands in the near UV region.In this paper,YVO₄:Bi³⁺,Ln³⁺ phosphors have been synthesized by high-temperature solid-state method andmicrowave method.The samples were characterized by X-ray powder diffraction?XRD?,photoluminescence?PL?spectra,luminescence lifetime and GSAS structure refinement.The refinement results indicated that introduced ionsare in the lattice sites of Y³⁺.Under 275 nm excitation,Y_1-xVO₄:xBi³⁺ has the optimum luminescence intensity when the concentration of Bi³⁺ is 0.02.And the emission spectrum is a broadband with emission peak localted at 540 nm,which is attributed to the 3P1?1S0 energy level transitions of Bi³⁺.Upon excitation at a wavelength of 275 nm,the optimum concentration of Ln³⁺?Ln=Eu,Dy,Sm?was0.06,0.03 and 0.04 in Y0.98-xVO₄:0.02Bi³⁺,xLn³⁺?Ln=Eu,Dy,Sm?samples were prepared by high temperature solid-state method,and the optimum concentration of Ln³⁺?Ln=Eu,Dy,Sm?was 0.05,0.02,and 0.03 in Y0.98-xVO₄:0.02Bi³⁺,xLn³⁺?Ln=Eu,Dy,Sm?samples were prepared by microwave method,corresponding to the electric dipole transition4F9/2?6H13/2?575 nm?of the Dy³⁺,the electric dipole transition 5D0?7F2?620 nm?of the Eu³⁺ and the magnetic dipole transition4G5/2?6H7/2?602 nm?of Sm³⁺,respectively.And the energy transfer efficiency of Bi³⁺?Ln³⁺?Ln=Eu,Dy,Sm?can reach69.57%,57.84%,42.62%,respectively.The Bi³⁺ can enhance the luminescence intensity of YVO₄:Ln³⁺.The excitation spectra of YVO₄:Bi³⁺,Ln³⁺ phosphors contain the charge transfer from 2p orbit of O2-to 4f orbit of Ln³⁺and the absorbing from energy level transition of Bi³⁺?1S0?3P1?and VO₄3-?¹A₁?¹T₂ and ¹A₁?¹T₁?through Gauss fitting.The energy transfermechanism of Bi³⁺?Ln³⁺ was also studied,which belongs to dipole-quadrupole mechanism of electric multipole interaction,and the critical distance?RC?between Ln³⁺?Ln=Eu,Dy,Sm?and Bi³⁺ were6.2 ?,7.7?,7.3?calculated by concentration quenching method.The emission color of YVO₄:Bi³⁺,Ln³⁺?Ln=Eu,Dy,Sm?can be modulated by the energy transfer of ions and the common emission of activator ions.In a word,the material has a good application prospects in the field of light emitting diode?LED?under UV excitation.