Preparation And Luminescence Properties Of Rare Earth Doped Fluoride Phosphors

Rare-earth fluorides are advantageous as ideal fluorescent host materials owing to their low vibrational energies minimizing multiphonon relaxation, sharper emission bandwidth, and low toxicity. As the important functional materials with many potential applications, fluorides phosphors are getting more and more attention. In the paper, Several rare earth doped fluorides materials have been synthesized, and the luminescence properties, energy transfer between certain rare earths were studied. The major achievement were as following:1. High quality lanthanide ions doped LuF3have been successfully prepared via the solvothermal method and using1-octyl-3-methylimidazolium hexafluorophosphate as fluoride source. Different morphologies and sizes of LuF3:Ln3+products can be obtained by tuning the synthesis temperature, time and using different kinds of solvents. The luminescent properties of the products with different morphologies were systematically studied, and their emission intensities strongly depend on morphology and size. The luminescence intensity of5D1â†'7FJ transition (J=0,2) got the highest when the doping concentration of Eu3+was5%while the luminescence intensity of the5Doâ†'7FJ (J=0-4) radiative transitions continue to increase.2. Gadolinium-based core/shell/shell nanostructure with a set of lanthanide ions incorporated into separated layers have been successfully synthesized. By the rational design of a core/shell structure we systematically investigated the luminescence properties of different lanthanide ions in NaGdF4host, and efficient down-conversion emission can be realized through gadolinium sublattice-mediated energy migration. By changing the doped lanthanide ions, we generated multicolour emissions from the luminescent Ln3+centers via energy transfer of Ce3+â†'Gd3+â†'Ln3+and Ce3+â†'Ln3+(Ln=Eu, Tb, Dy and Sm) in separated layers. In NaGdF4:5%Eu3+@NaGdF4@NaGdF4:5%Ce3+core/shell/shell nanotubes, with increasing the NaGdF4interlayer thickness, a gradual decrease in emission intensity was observed for the Eu3+activator. 3. NaGdF4:Tb3+, Eu3+phosphors have prepared by the hydrothermal method. Luminescence properties of NaGdF4:Tb3+, NaGdF4:Eu3+and NaGdF4:Tb3+, Eu3+were discussed. The luminescence colors of the Eu3+and Tb3+codoped NaGdF4samples can be tuned from green to white then to pale yellowish pink near the white region by simply adjusting the relative doping concentrations of the activator ions under a single wavelength excitation. With the fixed Tb3+concentration, the intensity of Tb3+decreased gradually as the increase of Eu3+, while the intensity of Eu3+was increasing. The fitting decay curves further proved the energy transfer between Tb3+and Eu3+.