Synthesis,Characterization And Luminescent Properties Of Rare Earth Luminescence Materials

Optical functional materials such as rare earth ions doped luminescence materials, carbon dots, photocatalysts etc. had drawn more and more attention due to their unique optical properties. In this thesis, rare earth ions(Eu³⁺, Tb³⁺, Ce³⁺) dopedβ-SrHPO₄ nanomaterials and Yb³⁺, Er³⁺/Tm³⁺ co-doped NaYF₄ upconversion nanomaterials have been synthesized by hydrothermal method. The phase structures,morphologies, luminescence property and photocatalytic activity of the as-prepared samples were investigated through X-ray diffraction（XRD）, scanning electron microscopy（SEM）, IR spectrum, energy dispersive X-ray spectroscopy（EDX）,transmission electron microscopy（TEM）, photoluminescence（PL） spectrum and so on. Moreover, a kind of carbon material with cuboid-like morphology was synthesized and explored its potential application for ion detection, and this carbon material can composite with rare earth ions doped NaYF₄ nanomaterials and improve the upconversion luminescence property. In addition, a visible-light photocatalyst BiVO₄ was obtained and investigated its photocatalytic activity. The experimental results were as follows:Undoped and rare earth ions(Eu³⁺, Ce³⁺, Tb³⁺) doped β-SrHPO₄ nanomaterials were successfully prepared by a facile hydrothermal method. The results indicate that after doping the rare earth ions, the phase of SrHPO₄ nanomaterials has nothing changed but lead to the change of morphology from nanoflakes to nanocrystals.Under the excitation of UV light, rare earth ions(Eu³⁺, Ce³⁺, Tb³⁺) doped β-Sr HPO4 nanocrystals exhibit the characteristic emission of Eu³⁺, Ce³⁺ and Tb³⁺ ions,respectively.A novel fluorescence carbon dots with cuboid-like morphology could be successfully synthesized by hydrothermal method using wheat straw as starting material and the luminescence property of these carbon materials were similar to carbon dots. When added a certain amount of fluoride into the carbon dots solution,the color of this solution changed from yellow to reddish brown. Based on the experimental analysis, it could be used as a sensor for detecting F– ions in aqueoussolution by naked eyes.Rare earth ions(Yb³⁺, Er³⁺ or Yb³⁺, Tm³⁺) doped NaYF₄ nanospheres, microrods and microtubes were synthesized through a simple hydrothermal method and compounded with cuboid-like carbon dots to form NaYF₄:Yb,Er（Tm）/CDs composites. The effects of CDs on the crystal phase, shape, size and upconversion luminescence of NaYF₄:Yb,Er（Tm） were investigated in detail. The results showed that the upconversion luminescence performance of NaYF₄:Yb,Er（Tm） increased significantly due to the modification with CDs.The BiVO₄ visible-light photocatalyst was formed by a simple hydrothermal method and investigated the impact of pH on the morphology. In the process of visible light-irradiated photocatalysis using dendritic-like BiVO₄ as photocatalyst and AgNO3 as additive, the BiVO₄:Ag heterostructure could be obtained. The formation of BiVO₄:Ag heterostructure could prominently improve the photocatalytic activity.