用沉淀法制备了尺寸约为8 nm的YVO4∶Eu3+纳米粒子,然后用反相微乳液法在YVO4∶Eu3+纳米粒子的表面包覆了一层SiO2壳。 利用XRD、TEM、UV-Vis吸收光谱和光致发光光谱对合成的样品进行了表征。得到的复合物具有较好的核壳结构,通过改变硅酸四乙酯的用量可以改变SiO2壳的厚度。研究了SiO2壳对YVO4∶Eu3+发光性质的影响,结果表明: 包覆和未包覆的样品在紫外光激发下都有Eu3+的特征发射; 随着SiO2壳厚度的增加,发光强度和量子效率越来越低,Eu3+格位对称性越来越高。

YVO4∶Eu3+ nanoparticles of about 8 nm were synthesized by precipitation reactions and coated with SiO2 by a reverse microemulsion method. Powder X-ray diffraction (XRD) patterns indicate that these nanoparticles are purely tetragonal phase. Transmission electron microscope (TEM) images show that YVO4∶Eu3+ nanoparticles are successfully coated with silica to form core-shell structured nanocomposites. The thicknesses of SiO2 shells can be altered by changing the volume of tetraethoxysilane (TEOS) used in the reaction. The ultraviolet-visible (UV-Vis) absorption spectra of YVO4∶Eu3+@SiO2 nanocomposites agree well with that of the YVO4∶Eu3+ nanoparticles colloid. Both the excitation and emission spectra are the same for YVO4∶Eu3+ nanoparticles and the nanocomposites. With the increasing of the thickness of SiO2 shell, the intensity ratio of 5D0-7F2/5D0-7F1 decreases, indicating that SiO2 shells can increase the local symmetry of Eu3+. All samples can emit bright red light under ultraviolet irradiation. The photoluminescence quantum yield decreases after SiO2 coating. With the increasing of the thickness of SiO2 shell, the photoluminescence quantum yield becomes lower and lower.