Controlled Synthesis And Research On The Luminescent Properties Of Rare-Earth Doped Compound Fluoride Nanoparticles

Up-conversion（UC） is a process, via multiple absorptions or energy transfers, converting low-energy light（usually near-infred or infred） to higher energies（ultraviolet or visible）. This phenomenon has been observed in some lanthanide ion-doped materials.The phenomenon is contrary to the law of Stokes, therefore UC also called Anti-Stokes. For uniqe electronic structure and luminescent properties of rare earth elements and low lattice vibration energy of compound fluoride, they became the ideal of up-conversion matrix materials. Lanthanide ion-doped compound fluoride are widely researched in fluorescence imaging、bio-labels as well as solid state laser and flat displays.The main purpose of this study is synthesized small size, strong luminescence, regulation morphology and monodisperse lanthanide ion-doped compound fluoride nanoparticles for bio-imaging, bio-labels as well as solid state lasers. At present, there are many chemical techniques to synthesize rare earth doped up-conversion nanoparticles, including sol-gel processing, solvo/hydrothermal synthesis and thermal decomposition method. Considering the thermal decomposition method overcome many shortages of sol-gel processing and solvo/hydrothermal synthesis, we choose the thermal decomposition method to synthesize Yb3+/Er3+ co-doped high quality, small size, regulation morphology and monodisperse Ba2GdF7, Ba4Y3F17 and LiBaF3 nanoparticles via vaccum sealing condition in oleic acid and 1-octadecence. The samples were characterized by Powder X-ray diffraction（XRD）, transmission electron microscope（TEM） and high-resolution transmission electron microscope（HRTEM）. The samples of upconversion emission spectra were obtained on a Hitachi F-4600 fluorescence spectrophotometer.There are three parts in this papar:（1） Monodisperse, small size and cubic structured Ba2GdF7 nanoparticles were synthesized by thermal decomposition method, using oleic acid as surfactant and 1- octadecence as solvent, by controlling the amount of sensitizer and activator, get the optimum concentration（The sensitizer was at 20% mol and activator at 4% mol） and research the sample of luminescence properties. XRD analysis showed that the cubic crystal phase of Ba2GdF7 nanoparticles, TEM analysis revealed that the cubic morphology, the average size of Ba2GdF7 nanoparticles is about 14 nm.（2）Ba₄Y₃F₁7 nanoparticles were synthesized in oleic acid and 1-octadecence at the reaction temperature of 310 oC, by controlling the amount of sensitizer and activator, get the optimum concentration（The sensitizer was at 20% mol and activator at 6% mol） and research the sample of luminescence properties. XRD, TEM analysis revealed that the morphology of Ba4Y3F17 nanoparticles is cubic, the phase is hexagonal and the average size of Ba4Y3F17 nanoparticles is about 9 nm.（3）LiBaF₃ nanoparticles were synthesized by thermal decomposition method, using oleic acid as surfactant, dispersant, stabilizer and 1-octadecence as solvent, by controlling the amount of sensitizer and activator, get the optimum concentration（The sensitizer was at 20% mol and activator at 2% mol） and research the sample of luminescence properties. XRD, TEM analysis revealed that both the morphology and the phase of LiBaF3 nanoparticles are cubic. The analysis also showed that the average size of LiBaF3 nanoparticles is about18 nm.