Effect of calcination temperature on the structural, optical and magnetic properties of pure and Fe-doped ZnO nanoparticles

Abstract

In the present study, pure ZnO and Fe-doped ZnO (Zn 0.97 Fe 0.03 O) nanoparticles were synthesized by simple coprecipitation method with zinc acetate, ferric nitrate and sodium hydroxide precursors. Pure ZnO and Fe-doped ZnO were further calcined at 450°C, 600°C and 750°C for 2 h. The structural, morphological and optical properties of the samples were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and UV-Vis absorption spectroscopy. The X-ray diffraction studies revealed that the as-synthesized pure and doped ZnO nanoparticles have hexagonal wurtzite structure. The average crystallite size was calculated using Debye-Scherrer's formula. The particle size was found to be in nano range and increased with an increase in calcination temperature. SEM micrographs confirmed the formation of spherical nanoparticles. Elemental compositions of various elements in pure and doped ZnO nanoparticles were determined by EDX spectroscopy. UV-Vis absorption spectra showed red shift (decrease in band gap) with increasing calcination temperature. Effect of calcination on the magnetic properties of Fe-doped ZnO sample was also studied using vibrating sample magnetometer (VSM). M-H curves at room temperature revealed that coercivity and remanent polarization increase with an increase in calcination temperature from 450°C to 750°C, whereas reverse effect was observed for magnetization saturation.

Effect of Thermal Treatment on the Phase Composition and Surface Properties of WO3‐TiO2 Nanocomposites Synthesized via Hydro‐Thermal Method

“…The hydrodynamic diameter showed an overall increase of about 128 % upon calcination at 1000 °C. The calcination results in growth of crystals along their preferred growth axis and for this reason the heat treated samples show higher particle size [5,46,51,55] . The crystallite size values of the nanocomposite obtained from XRD analysis (Table 2) are much lower than the hydrodynamic diameter values.…”

“…As the calcination temperature increases, the intensity of the peaks shows an increase, confirming increase in the crystallinity. The appearance of sharp and high intensity peaks indicates that the synthesized nanocomposite has high crystallinity [45–47] . Thus higher calcination temperature provides sufficient energy to form a highly crystalline form.…”

“…As the calcination temperature increases, the grain boundaries of the crystals come closer and several crystals fuse into a large sized single particle. At higher temperatures, migration of grain boundaries takes place and small grains coalesce to form large grains [46] . Thus higher calcination temperature caused growth of the crystals and resulted in the change in morphology of WO 3 ‐TiO 2 nanocomposites.…”

Photoluminescence and intrinsic ferromagnetism of Fe doped zinc oxide

“…Rekha et al and Arun et al also explain the blue shift behavior of their sample based on the Moss-Burstein theory [28,29]. The increase in bandgap or the blue shift behavior for the Fe doped sample with respect to that of pristine ZnO may also be because of the sp-d exchange interaction of localized d electron and band electrons as explained by Pal Singh et al [30].…”

“…There are also reports indicating the role of Zn i and V o in maintaining pure ZnO magnetic behavior. RTFM may be due to extrinsic phenomena such as the formation of cluster or secondary phase of dopant ions and intrinsic phenomena such as exchange interaction [30]. The XRD pattern indicates that there is no formation of secondary phases such as Fe 2 O 3 , Fe 3 O 4 , etc.…”