Preparation And Luminescent Properties Of Silver And Rare Earth Composite Nanometer Material

The rare earth ions, with abundant energy level and unique electronic structure of4f,have a number of characteristics such as lower toxicity, steadier chemical property,better light stability, narrower emission band, longer fluorescence lifetime, and havebeen widely used in biosensors, biological imaging, photothermal therapy,short-wavelength lasers, storage of information, white light illumination and solarcells,etc. But because of weaker luminescent properties and lower luminous efficiency,the rare earth ions need to be sensitized by other sensitizing agent, in order to enhancetheir luminescent properties. With the scattering on the light, the field enhancementeffect and surface plasmon resonance effect, the precious metal can take sensitizationeffect to the rare earth ions.In order to achieve fluorescence enhancement of the rare earth ions, thecomposite material of Ag@SiO₂@Er₂O₃has been designed and prepared by samesimple chemical methods, and conducted a series of characterization. In order toachieve fluorescence enhancement of the rare earth ions, the composite material ofAg@SiO₂@Er₂O₃has been designed and prepared by same simple chemical methods,and conducted a series of characterization. Through test the emission spectras with thechange of excitation power and comparison with the reference of Er₂O₃, theluminescence properties of Ag@SiO₂@Er₂O₃have been researched. The main resultsare as follows:Firstly, the composite material of Ag@SiO₂@Er₂O₃has been synthstised. Agnanoparticles have been prepared by a method of ethylene glycol reduction of silvernitrate, and the morphology of Ag nanoparticles have been controlled about60nm indiameter by PVP. With ethyl orthosilicate hydrolyzing in alkaline solution, a layer ofSiO₂shell has been coated around Ag nanospheres, and the thickness of the shell is about10-15nm. Erbium hydrogen carbonate has been coated around Ag@SiO₂by thereaction of erbium nitrate and carbamide, and then Ag@SiO₂@Er₂O₃has beenprepared through high-temperature treatment. The characterizations ofAg@SiO₂@Er₂O₃composite materials have been performance by TEM（transmission electron microscope）, XRD （X-ray diffraction） and Mapping （EDSscanning surface element distribution of spectrum analysis）, and the core-shellstructured of Ag@SiO₂@Er₂O₃has been proved.Secondly, the emission spectrums changed with excited power, ofAg@SiO₂@Er₂O₃composites and Er₂O₃reference sample in980nm laser excitation,have been tested. The composite material effectively reduces the threshold of whiteupconversion of Er3+ions. Under the same excitation power, the luminescenceintensity of the composite material was apparently higher than the that of thereference sample. Compering the relationship of luminescence intensity and excitingpower of two samples, composites fluorescence enhanced by3orders of magnitude,compared with the reference sample.At last, in the excitation of808nm laser, Ag@SiO₂@Er₂O₃composites observedupconversion luminescence and the reference sample almost no light.