Nanostructured ZnS powders with strong confinement effects prepared by colloidal precipitation method

We report the synthesis and characterization of nanostructured ZnS powders without using any capping agent. The synthesis was carried out by the wet chemical method. From X-ray diffraction analysis, it was found that nanostructured ZnS exhibited the cubic structure with an average size of 2.5 nm. High resolution transmission electron microscopy (HR-TEM) observations revealed the cubic structure with grain size of around 2.5 nm. In the UV–vis absorption spectrum, the absorption peak shows a blue shift with respect to bulk ZnS. The particle size estimated by considering the effective mass approximation is 2.1 nm. Photoluminescence spectrum exhibits two peaks at 360 nm and 450 nm. The emission color is blue for excitation at 245 nm with CIE coordinates x=0.14 and y=0.038 and it is bluish white when excited at 360 nm with CIE coordinates x=0.2 and y=0.36. It is demonstrated that quantum confinement effects are present in the nanostructured powders without the addition of any capping agent.