Preparation And Properties Of Rare Earth Ions Doped Single Matrix Phosphor For White LED

White LED as a new generation of green lighting source,compared with incandescent lamp and fluorescent lamp,it has the advantages of environmental protection,economy and long service life.Currently the most widely commercial white LED is implemented by combinig the LED chip with light conversion phosphors?pc-WLEDs?,so the phosphors coating on the chip is key to white LED luminous performance.The single matrix polychromatic phosphors which have higher quantum efficiency,heat and chemical stability,high light conversion efficiency,color purity and high color rendering are a hotspot of the current research.In view of the above points,several kinds of rare earth ions doped single matrix phosphors for white LED were prepared by sol-gel in this paper,and the phase behavior,luminous performance,energy transfer mechanism and so on were characterized by X-ray powder diffraction,field emission scanning electron microscopy,high power transmission electron microscopy,photoluminescence,quantum yield measurement.1.A series of SrGd AlO₄:A(A=Eu³⁺and/or Tb³⁺)nanocrystalline phosphors have been synthesized via a Pechini-type sol-gel method.Under the excitation of the near ultraviolet light,the prepared SrGdAlO₄:Ln³⁺(Ln³⁺=Eu³⁺and/or Tb³⁺)phosphors show both the characteristic red emission of Eu³⁺?5D_J?7F_J?J,J?=0,1,2,3transitions?and the characteristics green emission of Tb³⁺(5D₄?7F_6,5,4,3 transitions).There exists energy transfers from Gd³⁺to Tb³⁺,and Tb³⁺to Eu³⁺ions in SrGdAlO₄:Ln³⁺(Ln³⁺=Eu³⁺and/or Tb³⁺)phosphors.The luminescence color of SrGdAlO₄:Ln³⁺(Ln³⁺=Eu³⁺and/or Tb³⁺)phosphors can be tuned from blue to blue-green,green,white,orange,etc.by varying the doping species,concentration,and relative ration of the codoping Eu³⁺/Tb³⁺ions in SrGdAlO₄ host lattice to some extent.A single-phase white-light-emission has been realized in Tb³⁺/Eu³⁺codoped SrGdAlO₄nanocrystalline phosphors.The obtained SrGdAlO₄:Eu³⁺,SrGdAlO₄:Tb³⁺,and SrGdAlO₄:Eu³⁺,Tb³⁺nanocrystalline phosphors have potential application in the areas of UV white-light-emitting diodes and other optoelectronics lighting and display devices.2.A series of?Ca,M?MgSiO₄:Eu²⁺?M=Mg,Sr,Ba?nanocrystalline phosphors have been synthesized via a Pechini-type sol-gel method.XRD results showed that the matrix structure of CaMgSiO₄ host lattice does not change even when partial Ca²⁺ions are substituted by alkaline earth metal.Under the excitation of ultraviolet light,the(Ca_0.999-xMx)MgSiO₄:0.001Eu²⁺?M=Mg,Sr,Ba?phosphors show the characteristic emission of Eu²⁺?5d?4f electron transition?.In the CaMgSiO₄ matrix,when Ca²⁺ion was substituted by the ions with smaller radius,e.g.,Mg²⁺,it will cause the lattice contraction,and result in the red shift of Eu²⁺emission peak.However,when Ca²⁺ion was substituted by the ions with smaller radius,e.g.,Sr²⁺,Ba²⁺ion,replace the Ca²⁺site,and it will cause the lattice expansion,which makes the emission peak of Eu²⁺blue shift.The substitution of alkaline earth metal ions in?Ca,M?MgSiO₄:Eu²⁺?M=Mg,Sr,Ba?phosphor not only makes the emitting color tunable,but also will greatly improve the emission peak intensity of Eu²⁺.In Eu²⁺and Ba²⁺co-doped CaMgSiO₄nanocrystalline phosphors,the deep blue emission was realized.3.A series of CaTb Al₃O₇:Ce³⁺,Eu³⁺nanocrystalline phosphors have been synthesized via a Pechini-type sol-gel method.The XRD results show that CaTbAl₃O₇pure phase can be obtained at 1000 ^oC,and the doped rare earth ions do not affect the matrix lattice.Under the excitation of ultraviolet light,the CaTbAl₃O₇:Ln³⁺?Ln=Ce and/or Eu?phosphors show the characteristic red emission of Eu³⁺(⁵D_J?⁷F_J'J,J'=0,1 transition)and the characteristic green emission of Tb³⁺(⁵D₄?⁷F_6,5,4,3 transition).The experimental results show that,in CaTbAl₃O₇:Ce³⁺and CaTbAl₃O₇:Eu³⁺,both the Ce³⁺?Tb³⁺and Tb³⁺?Eu³⁺exist the efficient energy transfer,and all of them were dipole-quadrupole energy transfer mechanism.The energy transfer mechanism of Ce³⁺?Tb³⁺?Eu³⁺in CaTbAl₃O₇:Ce³⁺,Eu³⁺nanocrystalline phosphors can not only effectively transfer the energy of Ce³⁺to Eu³⁺,but also realize the orange-red emission by excitation of near ultraviolet light.