Effect of size reduction on structural and optical properties of ZnO matrix due to successive doping of Fe ions

In this work 0%, 3%, 5%, 7% and 10% Fe doped ZnO nanoparticles (NPs) have been successfully synthesized by the sol–gel method. The compositional, structural and optical studies have been investigated by XRD, FESEM equipped with EDS, TEM with SAED, UV–visible and Photoluminescence spectroscopy. XRD, SEM and TEM results confirmed the formation of nanoparticles with polycrystalline single phase nature with hexagonal wurtzite structure. The crystallite size has been found to vary between 10 and 20 nm with changes in the doping concentration of Fe. The stretching bonds in ZnO have been observed in FTIR spectra. The UV–visible and PL spectra show a red shift with increase of dopant concentration. The band gaps for all samples were calculated by the Tauc relation and narrowing of band gap from 3.33 eV to 3.26 eV with increasing Fe dopant concentration up to 10% was found. The band gap is narrowing because of the s–d and p–d exchange interactions which introduce a negative and a positive correction to the conduction and the valence-band edges respectively.