Inducing multiple functionalities in ZnS nanoparticles by doping Ni+2 ions

In this study, we propose that it is possible to induce multiple functionalities such as optical activity, electrical conductance and magnetism in single ZnS/Ni nanoparticles and exploit the same by only changing the external stimuli such as magnetic field, wavelength of light, electric field etc. Such type of material finds great significance in the field of electronics as well as in bioimaging. For the purpose, we have synthesized cubic ZnS:Ni2+ nanoparticles (NPs) using a simple wet-chemical method. Synthesized ZnS:Ni2+ NPs had been characterized by X-ray diffraction pattern (XRD) and energy dispersive X-ray (EDX) analysis. The amounts of Ni and Zn in the material were determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Morphology of the NPs is studied by transmission electron microscopy (TEM). Optical studies are carried out using UV–visible (UV–Vis) and Photoluminescence (PL) spectroscopies. Quantum efficiency of the material was also computed. The enhancement and quenching of the PL intensity are correlated with the ‘purity of the phase’. It is observed that change in packing of the molecules of the host material directly depended on concentration of dopant ion. The thermal study of the material was carried out using differential scanning calorimetry (DSC) to support the earlier proposition. Magnetic hysteresis behavior was studied using vibrating sample magnetometer (VSM). An interesting phenomenon of defect-induced magnetism was observed, which was enhanced on doping with Ni+2.

Figure shows spherical ZnS nanoparticle (light red) containing Ni as dopant ions (light green inside) exhibiting both optical (straight lines) as well as magnetic (elliptical field lines) activities simultaneously.Figure optionsDownload as PowerPoint slideHighlights
► A simple method has been adopted to synthesize Ni+2 doped ZnS nanoparticles.
► The enhancing and quenching of the PL intensity depended upon ‘purity of the phase’.
► The change in packing of the molecules in ZnS NPs directly depended on concentration of dopant.
► Magnetic and optical properties were found to be dopant dependent (e.g. Ni+2 ions).
► Proper choice of solvent for synthesis shows a marked effect on magnetism.