Saravanan Lakshmanan, Jayavel Ramasamy, Aldeyab Salem S, Zaidi Javaid S M, Ariga Katsuhiko, Vinu Ajayan
International Centre for Materials Nanoarchitectonics, WPI Research Centre, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
J Nanosci Nanotechnol. 2011 Sep;11(9):7783-8. doi: 10.1166/jnn.2011.4728.
Europium doped cadmium sulphide (Cd(0.98)Eu(0.2)S) nanostructures were synthesised by chemical co-precipitation method using ethylene glycol (EG) and deionized water (Eu:CdS-1), and isopropyl alcohol (IPA) and deionized water (Eu:CdS-2) as mixed solvents. It has been found that the nanostructure of the europium doped CdS can be controlled by simply varying the mixed solvent system. Powder XRD pattern reveals the formation of hexagonal (wurtzite) and cubic (zinc blende) structure for Eu:CdS-1, and Eu:CdS-2, respectively. The crystallite size of the sample prepared using IPA and deionized water was measured to be 2.64 nm which is much smaller than that of the sample prepared using EG and deionized water as mixed solvent (3.65 nm). Morphology of the materials can also be changed from flower shaped crystals to paddy like structures by varying the mixed solvents. Band gap values of Eu3+ doped CdS nanocrystals synthesized from two different solvents were estimated using UV-reflectance spectra. The size and crystallinity of the samples were confirmed by HRTEM and SAED analysis. A significant change in the PL emission of the CdS nanocrystals was observed for the europium doped CdS which is mainly due to the presence of EU3+ ions which also play a significant role in the energy transfer process. It was also observed that the shift in the emission and efficiency depends on size and shape of the synthesised nanoparticles.
采用乙二醇（EG）和去离子水（Eu:CdS - 1）以及异丙醇（IPA）和去离子水（Eu:CdS - 2）作为混合溶剂，通过化学共沉淀法合成了铕掺杂硫化镉（Cd(0.98)Eu(0.2)S）纳米结构。研究发现，通过简单改变混合溶剂体系就能控制铕掺杂硫化镉的纳米结构。粉末X射线衍射图谱显示，Eu:CdS - 1和Eu:CdS - 2分别形成了六方（纤锌矿）和立方（闪锌矿）结构。使用IPA和去离子水制备的样品的微晶尺寸测量为2.64纳米，这比使用EG和去离子水作为混合溶剂制备的样品（3.65纳米）小得多。通过改变混合溶剂，材料的形貌也可以从花状晶体变为稻粒状结构。利用紫外反射光谱估计了由两种不同溶剂合成的Eu3 + 掺杂硫化镉纳米晶体的带隙值。通过高分辨透射电子显微镜（HRTEM）和选区电子衍射（SAED）分析确认了样品的尺寸和结晶度。对于铕掺杂硫化镉，观察到硫化镉纳米晶体的光致发光发射有显著变化，这主要是由于Eu3 + 离子的存在，其在能量转移过程中也起着重要作用。还观察到发射和效率的变化取决于合成纳米颗粒的尺寸和形状。
