Preparation And Characterization Of Up-Conversion Rare Earth Fluorides Micro/Nanomaterials

The thesis expounds the features, current research situation at home and abroad, and up-conversion theory of up-conversion luminous materials. Rare earth fluorides normally possess a high refractive index and low phonon energy. Furthermore, they exhibit adequate thermal and environmental stability and therefore are regarded as excellent host lattices for up-conversion (UC) luminescence of lanthanide ions.In this thesis, the Up-conversion phosphors with Rare earth doped were synthesized in different experimental conditions, using YbF3, NaYbF4, GdF3 and NaGdF4 as host lattices. The main results were obtained as following:1. The phosphor prepared by the hydrothermal microemulsion has the better crystallization property and the higher luminous intensity, compared with the phosphor prepared by the microemulsion.2. The growth mechanism of theβ-NaYbF4 was discussed at the different shape modifiers. The (3-NaYbF4 grew horizontally using the sodium citrate as the shape modifier, while theβ-NaYbF4 grew vertically using the CTAB as the shape modifier.3. The luminous intensity is strengthened as the pump power increased. The double logarithmic plots show that the red and green emission of Er3+ are three-photon emission; the bule and near infrared light emission of Tm3+ are three-photon emission; the red emission of Tm3+ is four-photon emission; the red and green emission of Ho3+ are three-photon emission.4. CIE chromaticity diagram shows that double-doped NaYbF4 can be achieved white light emission.5. The NaGdF4:Yb,Er phoshors were prepared by hydrothermal microemulsion, hydrothermal method and microwave method. The luminescence of these NaGdF4:Yb,Er phosphors was compared:the fluorescence intensity of the NaGdF4:Yb,Er phosphor prepared by hydrothermal microemulsion is the strongest, and the fluorescence intensity of the NaGdF4:Yb,Er phosphor prepared by microwave method is the weakest.