Synthesis And Luminescence Properties Of Rare Earth Ion Doped YVO₄ Luminescence Nanomaterials

Rare earth ion doped YVO4 luminescence nanomaterials have received extensive attention because of their good physical and chemical stability, excellent luminescence properties and high efficiency of absorption to ultraviolet light. Thus, study on preparation and luminescence properties of rare earth ion doped YVO4 luminescence nanomaterials is of important significance and application value.The research object of this paper was rare earth ion doped YVO4 luminescence nanomaterials, in which the doped rare earth ions mainly included Eu3+, Tm3+ and Dy3+ ions. This thesis used a novel facile method, the ion exchange method, to prepare rare earth ion doped YVO4 luminescence nanomaterials. YVO4 nanocrystals prepared using the ion exchange method had rare earth ions mostly located on their surfaces. These rare earth ions could more easily coordinate with organic ligands to form inorganic–organic hybrid materials. In this thesis, X-ray diffraction(XRD), photoluminescence(PL) spectra, transmission electron microscope(TEM), ultraviolet-visible(UV-Vis) absorption spectra, Fourier transform infrared(FTIR) spectroscopy, ultraviolet analyzer and other characterization methods were used to analyze and characterize the crystal structures, micromorphology and grain size, chemical properties and luminescence properties of the rare earth ion doped YVO4 luminescence nanomaterials. This thesis includes the following parts.The solvothermal method was used to synthesize YVO4 nanocrystals, which were used to form YVO4:Eu3+ nanocrystals using the ion exchange method. 2-Thenoyltrifluoroacetone(TTA) ligands were introduced to form the YVO4:Eu3+–TTA inorganic–organic hybrid nanostructures. TTA has strong sensitization effect on the YVO4:Eu3+ nanocrystals. It was found that the YVO4:Eu3+–TTA inorganic–organic hybrid nanostructures exhibited strong luminescence. The luminescence intensity of YVO4:Eu3+–0.1 mmol TTA hybrid nanostructures was the strongest, and it was about 14 times as strong as the as-prepared YVO4:Eu3+ nanocrystals.The solvothermal method was used to prepare YVO4:Eu3+ nanocrystals, which were then annealed. The annealed YVO4:Eu3+ nanocrystals were used as core, and a new YVO4 shell was grown on their surfaces to the form the YVO4:Eu3+@YVO4 core-shell nanocrystals. Eu3+ ions were ion exchanged into the YVO4 shell to form the YVO4:Eu3+@YVO4:Eu3+ core-shell nanocrystals. TTA ligands were then introduced to the YVO4:Eu3+@YVO4:Eu3+ core-shell nanocrystals for form the YVO4:Eu3+@YVO4:Eu3+–TTA hybrid nanostructures. The sensitization effect of TTA in the YVO4:Eu3+@YVO4:Eu3+–TTA hybrid nanostructures was demonstrated. It was found that the YVO4:Eu3+@YVO4:Eu3+–TTA hybrid nanostructures not only had strong luminescence, but also had much wider excitation spectrum. The wide excitation spectrum can potentially enhance the luminescence efficiency of the YVO4:Eu3+@YVO4:Eu3+–TTA hybrid nanostructures.The ion exchange method was used to prepare YVO4:Eu3+, YVO4:Tm3+ and YVO4:Dy3+ nanocrystals, which exhibited obvious red, blue and green light emission, respectively. After optimizing the concentration ratio of Eu3+ ions, Tm3+ ions and Dy3+ ions, the YVO4:Eu3+:Tm3+:Dy3+ nanocrystals showed excellent white light emitting characteristics.Polymethyl methacrylate(PMMA) has excellent optical transparency and good impact resistance, so it is one of the most excellent transparent polymer materials at present. However, PMMA has its disadvantages, the biggest drawback is that PMMA cannot filter ultraviolet light. In this thesis, the ion exchange method was used to prepare YVO4:Ln3+(Ln3+=Eu3+, Tm3+, Dy3+) nanocrystals. Transparent PMMA/YVO4:Ln3+(Ln3+=Eu3+, Tm3+, Dy3+) were successfully synthesized with the radical polymerization of methyl methacrylate(MMA). The prepared PMMA/YVO4:Eu3+, PMMA/YVO4:Tm3+, PMMA/YVO4:Dy3+ and PMMA/YVO4:Eu3+:Tm3+:Dy3+ nanocomposites not only could greatly improve the PMMA effect and performance of filter ultraviolet light, but also could emit obvious red, blue, green and white light under ultraviolet light excitation.