Design,Synthesis And Luminescent Properties Of Rare Earth Doped Phosphate Phosphors

White LEDs are used as a new generation of illumination sources for their excellent luminescence properties and are widely used in various fields.The main way to implement white LEDs is to combine the chips with phosphors.At present,there are many problems in the use of commercially available phosphors in combination with devices,and their further application is restricted,which cannot meet the increasing demand for fluorescent materials,so the development of high-efficiency and stable UV the single-substrate phosphor excited by the near-ultraviolet chip is of great significance.In this paper,based on phosphate,Eu³⁺,Gd³⁺,Sm³⁺,Ce³⁺,Dy³⁺,etc.were selected as doping ions.Three preparation methods（microwave-assisted co-precipitation,co-precipitation and high-temperature solid phase method）were selected to prepare red or white fluorescent materials which with different structures and performance.The effects of calcination conditions and doping concentration on the luminescence properties of the materials were discussed.The thermal stability of the materials was also investigated.It is expected that the optimized preparation method and the selection matrix will provide a suitable doping structure for the rare earth,and the luminescence color of the material can be controlled by the energy transfer between the dopant ions to realize the red light and white light emission of the single substrate.The main research contents and results are as follows:（1）The red fluorescent material MgZn₂（PO₄）₂:Gd³⁺,Eu³⁺was synthesized by microwave-assisted co-precipitation.The effects of rare earth ion doping amount,calcination temperature and calcination time on the luminescence intensity of the material were investigated by designing a four-factor and five-level uniform test table.The materials were tested by XRD diffraction,fluorescence spectroscopy and thermal stability.The results of the analysis prove that the addition of Gd³⁺effectively sensitizes Eu³⁺ions.（2）MgZn₂（PO₄）₂:Ce³⁺,Dy³⁺white fluorescent materials were synthesized by co-precipitation method.The effects of the doping concentration and fluorescence thermal stability of Ce³⁺and Dy³⁺ions on the luminescence properties of the materials were investigated.The results show that MgZn₂（PO₄）₂ is used as the matrix of the material,and the material requires low temperature and good thermal stability when preparing materials.Through the energy transfer between ions,Ce³⁺effectively sensitizes Dy³⁺and achieves efficient single-substrate white light emission.（3）Ca₃Bi（PO₄）₃:Sm³⁺,Eu³⁺and Ca₃Bi（PO₄）₃:Ce³⁺,Dy³⁺fluorescent materials were prepared by high temperature solid phase method.The effects of ion doping amount,fluorescence thermal stability and other factors on the luminescence properties of the materials were investigated.The results show that the addition of Sm³⁺ions can effectively sensitize Eu³⁺ions.The luminescence color can be adjusted from orange red to red by adjusting the ion doping amount.The Ce³⁺and Dy³⁺co-doped fluorescent materials have high luminescence intensity and excellent thermal stability.Efficient single-substrate white light emission is achieved under excitation.（4）Preparation of fluoroapatite structure Sr₃YLi（PO₄）₃F:Sm³⁺and Sr₃YLi（PO₄）₃F:Ce³⁺,Dy³⁺fluorescent materials by high temperature solid phase synthesis.In order to study the luminescence properties of the materials,factors such as calcination temperature,doping ion amount,and fluorescence thermal stability were investigated.The results show that the addition of Sm³⁺ions realizes the luminescence of orange-red color;the Ce³⁺and Dy³⁺ions co-doped luminescent materials,and the high-efficiency white light emission of the sample is realized by the energy transfer between ions.