Effect of M = Fe, Cr, Sn, and Mg Substitution on the Structural and Optical Properties of Zn M S NPs

The Zn M S (M = Fe, Cr, Sn, and Mg) NPs were synthesized by applying the co-precipitation technique. The produced NPs’ structural, optical, and functional groups were identified by a variety of methods, including X-ray diffraction (XRD), UV-Vis Spectroscopy, Photoluminescence (PL), and Fourier transform infrared spectroscopy (FTIR). A cubical structure and strong XRD intensity were detected in the (111) plane direction of the generated nanoparticles. The Lattice parameter decreased with the doping concentrations mentioned above (~5.4–5.3 Å), and the average crystallite size of the nanoparticles fell between 1.8 and 4.3 nm. According to UV-Vis spectroscopy, the absorption edge moved to longer wavelengths with Cr, Sn, and Mg concentrations. Moreover, Fe doped ZnS NPs indicate that the absorption edge shifts toward a shorter wavelength side. The UV-vis spectra narrowed to 4.08, 4.10, 3.99, 3.85, and 3.89 eV, respectively, are used to estimate the energy band gap (Eg) of pure ZnS, Fe, Cr, Sn, and Mg doped ZnS NPs. Photoluminescence investigations revealed that pure ZnS NPs emitted deep-level emission (DLE) at 685 nm and near band-edge (NBE) at 435 nm. PL intensity rises with the addition of Mg and Cr to ZnS. Conversely, ZnS will be quenched by the concentration of Fe and Sn through a non-radioactive decay mechanism. The FTIR spectrum revealed the presence of functional groups in the prepared NPs.