Preparation And Luminescence Characteristics Of Rare Earth Doped Fluoride Nanocrystal

In this paper, up-conversion luminescence nanocrystal SrF₂ doped with rare-earth ions was prepared by hydrothermal method using Polyethylene Glycol as dispersant. The optimum composition of four types of samples was discussed, respectively, and optimally annealing temperature was determined. The ability of dispersant Polyethylene Glycol controlling the particle size was also discussed.The structure and morphology of the nanocrystals were analysised by X-ray diffraction(XRD) and transmission electron microscope(TEM). The result showed that the nanocrystals were rather monodisperse and with a relatively narrow size distribution and belong to cubic, and the average crystallite size of sample was about 50nm. The up-conversion spectrum was measured with Hitachi F-4500 spectrophotometer, Under 980 ran diode laser excitation. The impact of different concentration of rare-earth ions on the up-conversion luminescence intensity was discussed. And the optimum doped concentration of rare earth ions was obtained. The Ground state absorption, excitation state absorption and energy transfer were used in discusing the up-conversion mechanism of the sample and the pertinent up-conversion mechnism models of the sample were proposed.