Solvothermal Synthesis And Photoluminescence Properties Of Eu³⁺ Doped NaYF₄

NaYF₄ has two phases,hexagonal phase???and cubic phase???,?-NaYF4 has lower vibration energy,non-emissivity,good optical transparency,stable physicochemical properties and higher than?-NaYF4.Symmetry,therefore,has received widespread attention,making rare earth doped?-NaYF₄ widely used in displays,biotags,solar cells and other fields.The main research contents of this thesis are as follows:1.The solvothermal method was used to synthesize?-NaYF₄:Eu³⁺crystals with double-cone hexagonal prisms in deionized water-glycol system.The ratio of different deionized water and ethylene glycol to the microscopic analysis of?-NaYF₄:Eu³⁺crystals studied.Morphology,luminescence properties and fluorescence lifetime were analyzed,and the mechanism of solvent ratio on morphology and luminescence properties was discussed.The best experimental condition is that when the solvent is all deionized water,the morphology of the?-NaYF₄:Eu³⁺crystal is a double-cone hexagonal prism,and the luminous intensity is increased by 400%than the solvent.2.In the solvothermal method,OA was used as the surface,and?-NaYF₄:Eu³⁺crystallites were doped by heterogeneous Mn²⁺,and the phase,morphology,particle size and luminescence properties of doped Mn²⁺were studied.When the concentration of Mn²⁺is 5%,the luminescence intensity is the highest,which is 132.2%higher than that of doped heterogeneous ions.The higher the doping concentration,the finer the particles and the closer the aspect ratio is to 1.The shape of the particles is also changed from the micron-sized double-cone hexagonal prism shape to the nano-scale circular shape,and the?-NaYF₄:Eu³⁺,Mn²⁺phosphor with controlled morphology and size is realized.3.Through the hydrothermal method,adjust the pH value to 13,successfully synthesize one-dimensional Y?OH?₃ tubular phosphor,and then do different Eu³⁺doping to study the concentration of different Eu³⁺on Y?OH?₃ The phase,particle morphology and luminescence properties were studied,and the evolution mechanism of Y?OH?₃ tubular was proposed.It was found that when the Eu³⁺doping was 20%,the luminescence intensity was the strongest.The?-NaYF₄:Eu³⁺,Mn²⁺and Y?OH?₃:Eu³⁺are assembled into a core-shell structure,and the surface defects of the core are improved by the shell,so that the effect of improving the luminescence intensity is achieved.The effects of different core-shell structures on phase,microstructure and luminescence properties were studied.It was found that when the core-shell ratio was1,the luminescence intensity was the strongest,and the luminescence intensity of the unassembled core-shell structure was 191%.