中文摘要：

磁性光的 nanocomposites 等等在房间，磁性的回声成像和光成像的磁性的分离由于他们的潜在的应用获得了很多注意。此处，一个新、灵巧的二拍子的圆舞合成策略被开发准备磁性的 Fe3O4 修改单个水晶的起来变换光 NaYF4：Yb3+ ，把 Fe3O4 nanoparticles 用作种子的 Er3+ nanocrystals。在反应充当“原子核”， Fe3O4 nanoparticles 的存在便于起来变换 NaYF4 的形成：Yb3+ ，他们通过异构的成核过程的表面上的 Er3+ nanocrystals。这些多功能的 nanocrystals 的结构和性质被传播描绘电子显微镜(TEM ) ， X 光检查光电子光谱学(XPS ) ，相片光(PL ) 和 X 光检查衍射(XRD ) 。结果表明同样准备的多功能的 nanocrystals 显示出荧光灯的起来变换和 superparamagnetism 的双不同性质，它在形状并且很是立方的在有变化的一种平均尺寸的尺寸的制服 3040 nm。这些唯一的功能能为生物系统，和一些生物应用程序例如是很吸引人的标记房间也被表明。

英文摘要：

Magnetic-luminescent nanocomposites have obtained a great deal of attention due to their potential applications in magnetic separation of cells, magnetic resonance imaging and luminescence imaging, and so on. Herein, a new and facile two-step synthetic strategy was developed to prepare magnetic Fe304 modified single crystalline up- conversion luminescent NaYF4： Yb3＋, Er3＋ nanocrystals using Fe304 nanoparticles as the seeds. Acting as the ＂nu- clei＂ in the reaction, the presence of Fe304 nanoparticles facilitates the formation of up-conversion NaYF4： Yb3＋, Er3＋ nanocrystals on their surfaces through heterogeneous nucleation process. The structure and properties of these multifunctional nanocrystals were characterized by transmission electron microscope （TEM）, X-ray photoelectron spectroscopy （XPS）, photo luminescence （PL） and X-ray diffraction （XRD）. The results revealed that the as-prepared multifunctional nanocrystals show dual distinct properties of up-conversion fluorescent and superpara- magnetism, which were cubic in shape and very uniform in size with an average size ranging 30m40 nm. These unique functionalities could be very attractive for biological systems, and some biological applications such as cell- labelling were also demonstrated.