Preparation And Properties Of The Rare-earth Fluoride Luminescence Nano-materials

Rare earth luminescence materials have outstanding luminescent properties and wide potential application due to rare earth ions have special electronic shell structures. Fluorides become excellent host materials for luminescence materials owing to their diversity structural features,special physical and chemical characteristic. The properties of rare earth luminescent nano-materials largely depend on their structure, morphology and size.Therefore,the synthesis of luminescent nano-materials with controlled morphology and size has also aroused a lot of concern from the scientists. Amino acids can be used as templates to prepare nanomaterials with various shapes for their special functional group and self-assembling functions.In this thesis, rare earth fluoride luminescence nano-materials with different morphologies were synthesized with arginine and other surfactant-assisted hydro-thermal method. The structure and properties were characterized. The results were summarized as follows:1. GdF₃:Eu³⁺ nanomaterials with the morphologies of flat nanorods,nanoflowers and nanoflakes were prepared by PEG-2000,citric acid and glycine as surfactant-assisted hydrothermal method. Results showed that the morphologies are varied from the kinds of surfactants and the concentration of the reactant. The emission intensities are different from samples with different shapes. GdF₃:Yb³⁺,Er³⁺ upconversion luminescence nano-materials was prepared by citric acid-assisted hydrothermal method. Using 980nm laser as an exciting light, it can be observed the green emission band and red emission band in the upconversion fluorescenct spectra.2. YF₃:Eu³⁺ hollow caddice spherelike were prepared by arginine-assisted hydrothermal method. The influences of reaction time and temperature on shapes were discussed. With the increase of reaction time and temperature, the shapes of the samples have been changed from solid spheres into hollow spheres. The luminescence intensity clearly enhanced after heat treatment. The luminescence intensity of the Eu³⁺-doped YF₃ nanocrystal increased with the increasing doping concentration of Eu³⁺ ions and reached a maximum at 10mol%. YF₃:Yb³⁺,Er³⁺ shuttle-like upconversion luminescence nano-materials were prepared by the same method, the nano-crystals emitted the most bright green light, more intense red light and weaker blue light.