Structural and optical properties of Fe/Ni:ZnO nanoparticles:experimental and DFT studies

In the present study, Fe/Ni-doped ZnO nanoparticles (i.e., Zn0.90Fe0.10O, Zn0.95Fe0.05O; Zn0.90Ni0.05Fe0.05O and Zn0.85Ni0.05Fe0.10O) were successfully synthesized by the sol-gel technique. Fe/Ni-doped ZnO samples were characterized by X-ray diffraction, scanning electron microscopy, UV-Visible and IR spectroscopy. Structural, spectroscopic and optical properties of these Fe/Ni-doped ZnO nanoparticles were examined as a function of Fe and Ni concentrations. The X-ray diffraction analysis of doped samples confirms the formation of a hexagonal wurtzite structure. In addition, the FTIR spectra of the metal oxide nanoparticles confirm the ZnO nanoparticles. The surface morphological study was made with the help of scanning electron microscope (SEM) and the optical study was studied with the help of UV-Visible spectroscopy (UV-Vis.). The optical band gap, E-g of the diluted magnetic semiconductors was determined from the absorption spectra. The measured values of the band gap energy were found to be 2.88-3.04 eV. In addition, these nanoparticles were modeled as a cluster by density functional theory (DFT) calculations. In this theoretical study, the ZniOi, Fe-doped Zni-1Oi and Fe- and Ni-doped Zni-2Oi clusters (i = 6 and 10) were optimized as a wurtzite crystal structure by B3LYP/lanl2dz level. The spin states, structural parameters and the theoretical band gaps of all clusters were performed at same level. The HOMO and LUMO orbitals were visualized by GaussView.