Thesis Title:Synthesis And Luminescence Research Of Rare Earth Doped NIR Upconversion And Down Conversion Materials

The preparation, characterization and luminescence research of two kinds of NIR conversion materials were discussed in this work. The morphology controlled synthesis of Yb3+/Er3-doped Y2O2S was discussed in chapter2and the Bi3+/Yb3+doped GdVO4quantum-cutting material was dicussed in chapter3.In chapter1, we introduced the background knowledge of NIR conversion materials and application in practice.In chapter2, highly crystalline micro/nano sized Y2O2S were prepared through a one-pot mild (200-250℃)solvothermal synthesis. By simply adjusting the concentration of S2-, the morphology and size of the target product were20nm nanosheet,2μm sheet-assembled disk/flower and1.5μm nano-assembled sphere. We studied the upconversion luminescence of Yb3-/Er3+doped Y2O2S with different morphology. The result showed that nano-assembled sphere present the strongest green emission which should turn to less surface defect. For comparation, NaYF4:Yb3+/Er3+was prepared by solid state method, and our Y2O2S:Yb3+/Er3+showed the comparative emission intensity.In chapter3, Bi3+/Yb3+doped GdVO4quantum-cutting material was prepared by solid state method. The excitation spectra ranged from250nm to400nm and emitted strong NIR luminescence (900-1100nm). The XRD results showed that a high doping concentration(20%Yb3+,5%Bi3+) did not change the main phase. By introducing Bi3+, the NIR luminescence at989nm of Gd0.87Yb0.1Bi0.03V04increased by120%compared to Gdo.9Ybo.1VO4. he excitation peak shifted from323nm to341nm and broadened. This phenomenon can be:xplained by both the energy gained from O2-2ppâ†'V5-3d in substrate and1So-3P1of Bi3+can ransfer to Yb3+efficiently in this system. The optimized Gd0.87Ybo.iBio.o3V04showed stronger emission in both NIR and VIS than YVO4which have the highest QC yield reported by reference.