To enhance the strength and toughen of polymers filled with nano-SiO_2, the rare earth (RE) Ce doped nonstoichiometric nanometer silica compounds with a certain point defects were prepared by sol-gel methods. The RE-modified SiO_2 patterns were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Transmission electron microscope (TEM), and compared with unmodified SiO_2 samples. With the Ce content increasing, the lattice parameter of patterns and the IR spectra have changed. which is given a sound proof of Ce element entering the frame of silica. XRD measurement results show that when the content is lower than 8%, the silicon element is replaced by the cerium. But the 8% of doping content is higher, the free state oxides of doping ion are made by remanent RE elements of isomorphous replacement of Si~(4+), and the adsorption capability of samples decline because the partial cavities of SiO_2 are clogged. The RE cations are loaded onto the surface of compounds, which can be regarded as the Lewis acid sites. XPS approves that cerium as trivalent form exists in the three-dimensional network of silica further. Also TEM illustrates the particle size with good dispersion is about 30-50 nm. Finally, the mechanism of doping RE was studied.%为了提高纳米SiO_2粒子填充聚合物时的强度、韧性及亲水性能,通过溶胶一凝胶法制备出非化学计量掺杂Ce点缺陷的硅质纳米复合物,并进行了FT-IR、XRD、XPS、TEM的测试表征,考察了Ce的掺杂对纳米SiO_2结构及性能的影响.随着稀土元素Ce掺杂量的增加,样品晶胞参数和红外吸收光谱(FT-IR)发生变化,为Ce进人到SiO_2骨架中提供了有力证据.XRD结果表明掺杂量<8%时,Ce原子同晶取代Si原子.当掺杂量>8%时,进入孔道内未置换骨架原子的稀土元素会生成掺杂离子的氧化物游离相,从而堵塞SiO_2的部分细孔造成吸附性能的下降,而在复合物表面聚集的稀土元素可作为Lewis酸中心.X射线光电子能谱(XPS)进一步证明了铈主要以三价形式存在于SiO_2三维网状结构中.TEM测得样品的颗粒尺寸为30～50 nm之间,表明制备的样品具有较好的分散性和纳米粒度.同时对稀土元素的掺杂机理进行了初步的研究.
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