Investigation of the iron doping on the structural, optical, and magnetic properties of Fe-doped ZnO nanoparticles synthesized by sol-gel method

In this work, the compatibility of zinc oxide for spintronic applications motivated the development of single-phase Fe/ZnO nanostructures by a direct sol-gel method. The structural, morphology, optical properties, and magnetic properties of the samples were studied using X-ray diffraction (XRD), transmission electron microscopy, X-ray photoelectron spectroscopy, UV-Vis spectroscopy, and vibrating sample magnetometer. Rietveld refinement of XRD data demonstrated single-phase nanocrystalline of Fe-doped ZnO without any secondary phases and there is an expansion in lattice unit volume with increasing Fe concentration. The optical properties determined by UV-Vis spectroscopy showed decreasing in energy gap with dopant Fe. The magnetic measurements revealed that Fe-doped ZnO exhibits weak ferromagnetism at room temperature, with the value of magnetization increasing with Fe concentration. This room temperature ferromagnetism is caused by oxygen vacancy supported by bound magnetic polarons and probably grain boundaries. The dielectric measurements were carried out at 300 K and showed a decrease of both dielectric constant (epsilon(1)) and AC conductivity (sigma(AC)) with increasing the Fe content.