Coprecipitation Synthesis of Fe-doped ZnO Powders with Enhanced Microwave Absorption Properties

Abstract

In this work, the Fe-doped ZnO powders have been synthesized by a facile chemical coprecipitation method. The structure, morphology and magnetic properties of the as-prepared powders were characterized by X-ray di®raction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrum (EDS), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM). The results showed that the Fe ions were well incorporated into the crystal lattice of ZnO and had a valence state of þ3. The magnetization curves indicated the Fe-doped ZnO presented the ferromagnetic behavior at room temperature. Moreover, the electromagnetic (EM) parameters and microwave absorption properties of Fe-doped ZnO/para±n wax in the frequency range of 2-18 GHz were explored. The minimum re°ection loss reached À38:4 dB at 6.6 GHz, and the re°ection loss less than À10:0 dB was 4.0 GHz (from 11.0 GHz to 15.0 GHz) with a thickness of only 2.5 mm. Signi¯cantly, the enhanced microwave absorption of the as-prepared powders could be achieved by doping with Fe 3þ ions or varying the thickness of the absorbers. The mechanism of microwave absorption were attributed to the good impedance matching, the dielectric loss resulted from the crystal lattice defects and the magnetic loss originated from the natural resonance. It is believed that the Fe-doped ZnO powders could be used as potential microwave absorbers.

Enhanced Photocatalytic Activity of ZnO Toward the Degradation of Methylene Blue Dye: Effects of Fe3+ and Sn4+ Doping

“…The spectrum of Fe 2p (Figure c) showed two peaks at 711.56 and 725.41 eV, which corresponded to the binding energy of Fe 2p 3/2 and Fe 2p 1/2 , respectively, exhibiting an energy difference of 13.85 eV. In a previous study, the binding energy of Fe 2p 3/2 and Fe 2p 1/2 in Fe 2+ ions was located at 710.30 and 722.30 eV (the energy difference was 12.00 eV), respectively, whereas that in Fe 3+ ions was located at 710.70 and 724.00 eV (the energy difference was 13.30 eV), respectively. The data in Figure c were similar to findings from Fe 3+ ions, so the doping valence state of Fe was considered Fe 3+ .…”