Study On Synthesis And Luminescent Of KY₃F₁₀:Yb, Tm/Ho And ZnS:Cu

In recent years, the applications of fluorescent labeling materials have successfully expanded to the high sensitive biological detection and bio-imaging fields with the development of modern medicine, molecular biology. For example, fluorescent labeling materials have been used for real-time detection interactions between variety proteins and cells in vivo, which provides a more effective way to understand the complex interactions and the movement between biological molecules. It's necessary to synthesis the nanoparticles with spherical shape,monodispersed,small particle size and high luminescence efficiency. On the above bases, This thesis mainly researehed on the synthesis and luminescence property of KY3Fio:Yb,Tm(Ho) rare-earth phosphors and semi-conduetor ZnS:Cu nanocrystals.The main contents and results are as ofllowing:(1) KY3F10:Yb,Tm nanocrystals were synthesized from trifluoroacetate precursors via a thermal decomposition method, and the upconversion luminescence (UCL) properties of the nanoparticles were studied. The XRD and TEM analysis results show that pure cubic phase, small size(～13nm), monodisperse size distribution, irregular shape and high luminescence efficiency KY3F10:Yb,Tm nanoparticles are obtained. By changing the concentration of rare earth doping, the optimal doping concentration ratio was ensured. Power-dependent investigation reveals that the blue(481nm) and red(646nm) upconversion fluorescence are three-photon upconversion process.The UCL mechanism of the Yb3+-Tm3+system in nanosized KY3F10 is also discussed.(2) By the same experimental technique, KY3Fio:Yb,Ho nanocrystals were synthesized. Through changing the concentration of rare earth doping, the optimal doping concentration ratio was ensured. Power-dependent investigation reveals that the green(541nm) and red(659nm) upconversion fluorescence are double-photon upconversion process.The UCL mechanism of KY3Fio:Yb,Ho nanoparticles is also discussed. The effects of the oleic acid content on the morphology and particle size were studied. In the conditions of different oleic acid content, pure cubic phase of KY3Fio:Yb,Ho nanoparticles are obtained. With the increase of oleic acid content, nanoparticles size increased and dispersity was better. When the oil amine instead of oleic acid, crystal size is decreased, but the dispersion is poor.(3) Sulfur metal-organic complexs were synthesized with Zn(NO3)2, Cu(NO3)2 and DDC(Diethyldithiocarbamate) as raw materials. Bright purple emission a-ZnS:Cu nano phosphors were synthesized through pyrolysis sulfur metal-organic complex at 200℃. The XRD and TEM result shows that high temperature phase a-ZnS with hexagonal structure is obtained. The phosphors are well-dispersed spherical particles with a mean diameter of about 30nm. The excitation spectra of phosphors with the peak value at 235nm show obvious blue-shift as compared with that of bulk a-ZnS:Cu (at 330nm), which arises from quantum confinement effect that makes the optical band gap ofα-ZnS:Cu nanoparticles broadening. Under the excitation of 243nm, the emission bands around 285nm,396nm,486nm and 545nm are detected, and the emission band around 396nm is the strongest. With the increase of copper ion concentration, the luminous intensities of all emission bands increased firstly and then decreased. The intensity achieves the maximum as the content of copper ion is 1.0%. The emitting mechanism of theα-ZnS:Cu is also discussed.