Effect of ZnO coating on two different sized α-Fe nanoparticles: synthesis and detailed investigation of their structural, optical, hyperfine and magnetic characteristics

Abstract

The growth of metal–semiconductor (α-Fe/ZnO) bi-functional nanocomposites (NCs) by a wet-chemical route has been reported in the present article. Structural characterization by X-ray diffraction measurements confirmed the formation of the pure phase nanocomposite along with some oxide impurity appeared as the surface passivation layer on Fe nanoparticles. Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopic studies have demonstrated the nature of the functional groups present in the samples. A red shift in the ultraviolet–visible (UV–vis) spectrum of the NCs indicates the band gap modification of ZnO due to the presence of metallic α-Fe nanoparticles in close proximity. Photoluminescence (PL) emission spectra of the NCs show a blue shift with respect to the pristine ZnO which corroborates the close-proximity effect. The successful formation of nanocomposite is also evidenced from the band shift observed in UV–Vis and PL spectra. Some defect related emission peaks are also traced in the PL spectra. Magnetization measurements reveal that the saturation magnetization is very high for these NCs attributed to the dominant surface contribution. Mossbauer study traces some paramagnetic phase formed due to the surface passivation layer along-with larger particles of Fe in the ordered state.