Preparation And Properties Of New Scheelite Structured Luminescent Materials

In rare earth doped luminescent materials,most of the substrates have low chemical stability,thermal instability,low color rendering index and weak absorption of ultraviolet light band,which limit their application range.To solve this problem,this paper prepared tungstate system self-activated matrix material,which has strong absorption in the ultraviolet light band,high stability,excellent luminescence performance and has potential application value.The main research results are as follows:?1?A series of Eu³⁺,Dy³⁺,Tb³⁺doped novel scheelite structures LiCaGd?WO₄?₃:Ln³⁺?Ln=Eu,Dy,Tb??LCGW?phosphors were prepared by high temperature solid state method.The results show that Eu³⁺,Dy³⁺and Tb³⁺ions were successfully introduced into the host lattice of LCGW without obvious impurity peaks.Under ultraviolet radiation,Eu³⁺and Tb³⁺single-doped LCGW phosphors emit red and green light,respectively.In addition,the LCGW phosphors doped with Dy³⁺emit yellow,and the optimal doping concentration was 0.08 mol.An effective energy transfer phenomenon was observed between Eu³⁺/Dy³⁺and Tb³⁺/Dy³⁺ions.By adjusting the concentration of Tb³⁺or Eu³⁺,the adjustable effect of color can be achieved.The samples also have good thermal stability and high color purity.?2?Li₂Ca?WO₄?₂:xDy³⁺,Li₂Ca₂WO₄SiO₄:y Dy³⁺,LiCa₂WO₄PO₄:zDy³⁺phosphors with new scheelite structure were successfully prepared by high temperature solid state method.Among them,the[SiO₄]^4-and[PO₄]^3-ions replace the[WO₄]^2-ion in the tungstate,which has little effect on the crystal structure of the Li₂Ca?WO₄?₂ matrix materials.The samples prepared are pure scheelite structure.The three fluorescence materials doped with Dy³⁺all emit yellow light,and the emission peak is located near576 nm,and the optimal doping concentration is 0.08 mol.The luminescence properties of Li₂Ca?WO₄?₂ matrix materials changed significantly after[SiO₄]^4-and[PO₄]^3-ions replace[WO₄]^2-ions,in which LiCa₂WO₄PO₄:zDy³⁺fluorescent materials have the best luminescence properties,decay lifetime and thermal stability.?3?The high-temperature solid phase method and hydrothermal method were used to prepare the new scheelite structure of LiCaLa?WO₄?₃:Ln³⁺?Ln=Eu,Dy,Tb?fluorescent materials.The samples doped with Eu³⁺,Dy³⁺,Tb³⁺ions showed red,yellow and green emission peaks at 617,576 and 546 nm,respectively.In addition,the luminescence properties,thermal stability and color purity of the samples prepared by solid phase method were higher than those prepared by hydrothermal method.