| At present, the most popular attention field is the combination of nanotechnology and biotechnology, nanocrystals is an important bridge to connect the two areas. Fluorescence nanocrystals has excellent optical properties and can be used as biomarkers, whose properties may exceed extensive use of organic dyes markers in many aspects and bring great breakthrough in the field of biology and medicine. Meanwhile, it will greatly accelerate the development process of nanometer technology. Being a new biomarkers nanocrystal has several advantages over traditional organic dyes markers. Such as wide and continuous excitation spectrum, narrow symmetrical emission peak, high luminous efficiency, good photochemical stability, emitted color correlated with its size and so on. A single nanocrystalline material can produce different color of monochromatic according to their size change, even white which is impossible for organic dyes. The controllable synthesis of nanocrysyal is an important constituent in the development of nanotechnology and the foundation to explore the nanostructure properties and application. This thesis studied the chemical controllable synthesis of some semiconductor and oxides nanocrystalline and discussed quantum confinement effects, discussed the influence of crystal synthesis method and its structure on the luminescence properties. Forecast the potential use as fluorescent marker from its luminous properties.The main results in the thesis are as follows. (1) Regular sphericity, monodisperse ZnSe nanocrystals were synthesized by mild hydrothermal route. The relationship of luminescence properties and the particle size and morphology under the ultraviolet excitation was studied, the bandgap of ZnSe nanocrystalline was calculated, and luminescence mechanism with the defects was analyzed. (2) ZnS nanocrystals were prepared by solution method. Different morphology and luminescence properties of ZnS nanocrystalline was obtained by changing the reaction parameter. The defect state, vacancy, adsorption and interstitial atoms that effect luminous properties of ZnS nanocryatals were studied. The luminous process of limited state and all kinds of defect in the ZnS nanocrystals was raised. (3) Mn2+-doped ZnS nanocrystals and Mn2+-doped ZnS nanoparticles coated with a shell of Zn(OH)2 have been prepared via soft template and precipitation reaction. The volume ratio of alcohol and water (a/w) in the template has a great effect on the luminescence properties for ZnS:Mn particles. ZnS:Mn/Zn(OH)2 core/shell nanocrystal exhibits much improved luminescent properties and higher absolute quantum efficiency than those of unpassivated ZnS: Mn nanocrystals. Meanwhile, simply explore the formation mechanism of ZnS:Mn nanocrystals in alcohol and water system and analogize the reason that alcohol and water cluster structures affect the luminescent properties of nanoparticle. (4) Gd2O3:Dy3+ nanocrystals have been synthesized by solvothermal method followed by a subsequent calcination process. The influence of solvent, heat treatment temperature and grain size on the luminescence properties of Gd2O3:Dy3+ nanocrystals were studied. The emission spectrum of nanocrystals were broadened with the particle size decreases without the change of structure, the reason can be ascribed to surface effect and relevant luminescence mechanism was explored through Judd Ofelt theory. (5) MgO:Eu3+ nanocrystals were prepared via facile combustion method under a weak reductive atmosphere at a low temperature. Two kinds of luminescence sites of Eu3+ are identified by means of the fluorescence decay and site selective spectroscopy. Some of them located at the disordered sites near the surface or absorbed at the surface of MgO host and the other Eu3+ ions are incorporated into the inner MgO lattice site.
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