核/壳结构的ZnS:Mn/SiO_2纳米粒子的制备及发光性质研究

采用溶剂热法制备了Mn离子掺杂的ZnS纳米粒子(ZnS∶Mn),然后利用正硅酸乙酯(TEOS)的水解反应对其进行了不同厚度的SiO2无机壳层包覆。采用X射线衍射(XRD)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)及荧光发射光谱(PL)对样品的结构及光学性质进行了表征和研究。包覆SiO2壳层后,粒子的粒径明显增大并且在ZnS∶Mn纳米粒子表面可以观察到明显的SiO2壳层。XPS测试印证了ZnS∶Mn/SiO2的核壳结构。随着SiO2壳层的增厚,ZnS∶Mn/SiO2的Mn离子的发光先增强后减弱,这是因为SiO2壳层同时具有表面修饰和降低发光中心浓度这两种相反的作用。当壳层厚度(壳与核的物质的量的比)达到5时,发光效果达到最好,其强度达到未包覆样品的7.5倍。

Synthesis and Photoluminescent Properties of Core/Shell Structure ZnS:Mn/SiO_2 Nanocrystals

Mr-doped ZnS nanopatricles synthesized by solvothermal method were successfully coated with SiO_2 shells of various thicknesses by hydrolysis reaction of tetraethyl orthosilicate (TEOS).The samples were characterized by X-ray diffraction (XRD),transmission electron microscopy images (TEM),X-ray photoelectron spectroscopy (XPS) and the room temperature photoluminescence (PL) spectra When the ZnS:Mn nanoparticles were coated with SiO_2 shells,an obvious increase in particle size and a clear shell of SiO_2 can be observed.The XPS measurement also gave the evidence for the core/shell structure of ZnS:Mn/SiO_2 nanoparticles.Because the surface modification effect and the decrease in luminescent centers effect are concurrent in the SiO_2 shells,the Mn emission intensity first increased and then decreased with the thickening of the SiO_2 shell The intensity,which attained its maxium at 5 shell thickness,was as 7 times as that for the bare.ZnS,Mn nanoparticles.