Researches on the Preparation and Properties of Rare-earth Metal Ions Doped Silicate-based Luminescent Materials

Abstract: Ce and Eu ions doped Sr_2MgSi_2O_7 materials had been prepared by hydrothermal and sol-gel methods. Effects of synthesized methods, annealing temperature and time and concentrations of rare-earth metal ions on the structures and the luminescence properties of the silicate materials were studied using X-ray diffractometer (XRD), transmission electron microscope (TEM) and spectrofluorometers (PL). The results show that the Sr_2MgSi_2O_7 phase can be obtained by the hydrothermal method operated at 220℃for 2d, and the content of the Sr_2MgSi_2O_7 phase increases when increasing the reaction time to 6d. When the hydrothermal products were heat treated at 800℃, the mail phase of the products is Sr_2MgSi_2O_7 with a little bit impurity, i.e., SrSiO_3 phase. The products obtained employing the sol-gel method operated at 1000℃mainly consists of Sr_2MgSi_2O_7 phase and small amount of Sr_2SiO_4 impurity. Studies on the photoluminescence patterns show that the wide UV emission band with the wavelength at 371nm exists in both Ce ions doped Sr_2MgSi_2O_7 samples synthesized by the hydrothermal method and sol-gel method. This emission originates from the 5d-4f electron transition of Ce ions existing in the Sr ions place in the Sr_2MgSi_2O_7 crystals. Two red emission bands with the wavelength at 590nm and 612nm excited at 395nm can be observed in the Eu ions doped Sr_2MgSi_2O_7 samples obtained by sol-gel method, after heat-treated in air. However, only one emission band with the wavelength at 604nm with the excitation band at 403nm exists in the Eu ions doped Sr_2MgSi_2O_7 samples obtained by hydrothermal method, after heat treated in air. In these two kinds of the samples obtained by the sol-gel and hydrothermal methods, a blue emission band with the wavelength at 465nm can be obtained when heat-treated in hydrogen atmosphere, and the intensity of this blue emission increases with the increasing of the heat treating temperature…
Key words: hydrothermal method; sol-gel; Sr_2MgSi_2O_7; photoluminescence; rare earth metal; ions doping

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