Influence of thermal annealing on the structural and optical properties of maghemite ( gamma -Fe sub(2)O sub(3)) nanoparticle thin films

In this study, maghemite ( gamma -Fe sub(2)O sub(3)) nanoparticles were initially synthesized via chemical co-precipitation and then deposited by spray pyrolysis as thin films on white glass substrates. The thin films were annealed for 8h at 400, 450, 500, 550, and 600 degree C in an oven. The structural studies of maghemite nanoparticles were carried out using X-ray diffractometer. Structural properties that we investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, SEM, and Energy dispersive X-ray analysis (EDS). Optical properties of the samples were also investigated by ultraviolet-visible (UV-vis) spectroscopy. The results showed that maghemite nanoparticles have crystalline structure with domain that increases in size with increasing annealing temperature. The optical band gap values were found to reduce from 2.9 to 2.4eV with increase in annealing temperature. Copyright copyright 2015 John Wiley & Sons, Ltd.