| Fluoride doped different rare earth luminescent element is a very good base material due to their unique luminescence features. And it can be divided into two parts the up-conversion or down-conversion with optical performance, which has potential applications in the field of biology and medicine. However, NaYF4:Yb3+ / Er3+ as the most efficient luminescence nanocrystals can not meet the need for the development.Therefore, according to the coated homogeneous and heterogeneous shell method this paper mainly introduce a beneficial hydrothermal method, in which coating the prepared SiO2,TiO2 as homogeneity shell with luminescent particles NaGdF4 core. The morphology of nuclear materials is relatively regular hexagonal prism, and then coating with a layer of relatively rough surface of NaGdF4 shell. The experiment methods and reaction conditions do not change based on the effects of different concentrations of Yb element, and light-emitting situation is different doping system. By contrast, the coated layer can enhance the emission intensity. Here also we discussed the transformation of light-emitting mechanism.We successfully prepared NaGdF4:Yb,Ho@SiO2 and NaGdF4:Yb,Ho@TiO2 core-shell materials. Morphology of nuclear materials is relatively regular hexagonal prism,and then coated on the surface of a dense uniform SiO2 or heterogeneous TiO2 shell. Obtained in this experiment pH = 6 in favor of the preparation of high-intensity light-emitting materials. By contrast, the coated layer sample can enhance the luminous intensity.We successfully produced rare earth doped NaGdF4 micron particles. Then we smoothly prepared the NaGdF4: Yb, Tm, Ho@SiO2 core-shell materials. NaGdF4 micron particle samples comparing core-shell materials are very strong on the up-conversion intensity.Further more, by adjusting Tm/Ho ratio it can give white emission. And after SiO2-coated shell,glowing white transformed into a significantly enhanced. |
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