Green synthesis of ZnS nanoparticles using allium sativum l. extract and study of their structural, optical and electrical properties

This work presents a simple, low-cost and environmentally friendly approach for the synthesis of zinc sulfide nanoparticles (ZnS NPs) using Allium sativum L. plant extract. Formation of cubic ZnS NPs is confirmed from X-ray diffraction study. Transmission electron microscopy image confirms the formation of spherical particles of average size 6.5 nm. Direct band gap energy of the NPs is found to increase from 3.87 - 4.25 eV with increasing volume of the extract. Fourier transform infrared spectroscopy analysis confirms the presence of biomolecules in the extract which are involved in the formation of ZnS NPs. The possible growth mechanism of ZnS NPs within the biopolymer matrix has been discussed. The dielectric constant of ZnS NPs is higher than the bulk ZnS. A.C. conductivity increases with increasing frequency and changes practically linearly with applied frequency. The impedance study suggests that the ZnS samples could be used as nano-tuned devices in electronics. It is found that as crystallite size decreases, d.c conductivity rises.