Preparation And Electromagnetic Property Of Ni_0.5Zn_0.5Fe₂O₄ And Fe₃O₄

As the category of the typical ferrite materials Ni0.5Zn0.5Fe2O4 and Fe3O4 have excellent electromagnetic wave absorption performance. In this paper, the effect on sintering temperature of Ni0.5Zn0.5Fe2O4 using alcohol-water coprecipitation method with different alcohol-water ratios(0:1, 1:4, 1:3, and 1:2); the structures and electromagnetic properties of Ni0.5Zn0.5Fe2O4 doped with Li and La; the preparation, morphologies and electromagnetic properties of Ni0.5Zn0.5Fe2O4/C and Ni0.5Zn0.5Fe2O4/PANI; and the structures and electromagnetic properties of Fe3O4 and Fe3O4/C, these all had been studiedThe XRD results of samples with different alcohol-water ratio show that the pure Ni0.5Zn0.5Fe2O4 phase only can be obtained at 700 ℃ for 4 hours with the alcohol to water ratio is 1:2.XRD and electromagnetic parameter measurement results show that the lattice constants of samples doped two different ratios Li increase, the conductivity and dielectric losses are enhanced, the magnetic loss is reduced, the reason of absorption performance decrease is that the increase of dielectric loss is smaller than decrease of magnetic loss; the lattice constants of samples doping two different ratios La increase, the conductivity and dielectric loss are enhanced, conductivity and dielectric loss increase are proportional to amount of La, the magnetic loss is reduced, because of the dielectric loss increase smaller than the magnetic loss reduced, the absorption performance is reduced with the increase of La doped.Using glucose as carbon source, Ni0.5Zn0.5Fe2O4/C composites were successfully synthesized in the hydrothermal condition, and the amount of glucose on morphologies and electromagnetic properties of the composite effect of were studied. Experimental results show that the carbon was adsorbed on the surface of ferrite with small amount of glucose, carbon sphere was formed with large amount of glucose; conductivity and dielectric loss of Ni0.5Zn0.5Fe2O4/C composites are improved, magnetic loss and absorption loss of Ni0.5Zn0.5Fe2O4/C composites are reduced with C content increases.Ni0.5Zn0.5Fe2O4/PANI composites were prepared using in-situ method, their morphologies and electromagnetic properties were also studied. The XRD results show that with the aniline increase, PANI was adsorbed on the surface of ferrite firstly,and then the ferrite had been stuck together by PANI, the lamellar structures of the PANI were formed finally; The results of electromagnetic parameters measurement of the Ni0.5Zn0.5Fe2O4/PANI composites show that conductivity, dielectric loss and absorption loss are enhanced, and the magnetic loss is reduced with the increase of polyaniline.Fe3O4 nanoparticles and Fe3O4/C nanoparticles were synthesized by a simple hydrothermal method. The carbon from the glucose may restrain the growth of Fe3O4 nanoparticles. The Fe3O4/C has self-assembled rod-like nanostructures with averaged diameter of 10 nm and length of 200 nm. Fe3O4/C nanoparticles are self-assembled by Fe3O4/C nanoparticles. The saturation magnetization of Fe3O4/C nanoparticles is 41.7 emu/g. The higher conductivity and dielectric loss of Fe3O4/C nanoparticles compared with Fe3O4 nanoparticles is ascribed to the amorphous carbon. Due to the existence of carbon layer, the real part of permeability of Fe3O4/C nanoparticles is higher than that of Fe3O4 nanoparticles at 2-16 GHz. Two overlapped peaks of imaginary part of permeability in Fe3O4 nanoparticles are from the natural and exchange resonance.