Preparation And Multicolor Fluorescence Properties Of Rare Earth Fluoride And Phosphate Materials

In recent years,rare earth doped luminescent materials have attracted a lot of attention due to their potential applications in solid state lasers,solar cells,fluorescent probes and many other areas.Rare earth have abundant energy levels because of their unique electronic configuration and these energy levels can be selected to absorb or emit designated light.This is the reason why rare earth are popular in the optical field.In addition,the phase,dimension and morphology of the luminescent material will have a certain effect on its physical and chemical properties,thus affecting the properties of the material.Therefore,it is of great significance to design and synthesize micro-nano optical functional materials with good dispersibility,uniform size,controllable morphology and high purity,and further study the growth mechanism of microstructure.Among many methods for preparing optical functional materials,hydrothermal method has been widely used in various preparations in recent years due to its advantages of mild preparation conditions,stable system,low synthesis temperature,good crystallinity and low environmental pollution.In this thesis,rare earth doped fluoride(KSc₂F₇,KYb₃F₁₀)and phosphate?Na₃Sc₂?PO₄?₃? were prepared by mild hydrothermal method.At the same time,many factors affecting the growth mechanism of the microstructure of the material are controlled?such as ion concentration,temperature,pH and additives?.The phase,morphology and luminescence properties of the product were studied.The growth mechanism of each form was revealed to better understand the crystal growth process.The specific research content is divided into three parts.One is to prepare the well-formed KSc₂F₇ crystallites?including microrods,sheets,flowersand thin rectangles?by changing the F/Sc ratio,pH and surfactant.).In addition,In addition,doping Ln³⁺with larger radii contributes to the formation of bigger particles,which provides a novel way to control the shape and size of other similar microcrystals.The obtained KSc₂F₇:Ln³⁺products showed multicolor emission with red(Eu³⁺),green(Tb³⁺)and blue(Ce³⁺),respectively.The second is to synthesize a series of color-tunable emitting Na₃Sc₂?PO₄?₃:Ce³⁺/Tb³⁺/Eu³⁺?NSPO?phosphors by a combination of hydrothermal and low temperature calcination.The phase structure,photoluminescence and energy transfer property of the samples were studied in detail.The third is that KYb₃F₁₀:Ln³⁺?Ln=Er,Ho,Tb,Gd,Eu,Sm,Ce and La?micro/nanocrystals with abundant morphologies were synthesized via manipulating the different environments of crystal growth,such as increasing the concentration of F^-,adjusting pH,using different fluoride source or adding trisodium citrate.The obtained KYb₃F₁₀:Ln³⁺?Ln=Tb,Eu?products showed bright emission colors with red(Eu³⁺)and green(Tb³⁺),respectively.