Synthesis, Characterization and Electromagnetic Studies on Nanocrystalline Zinc Ferrite by Polyacrylamide Gel

摘要

Nanocrystalline zinc ferrite was synthesized by polyacrylamide gel method with acrylamide as monomer and N, N'-Methylenediacrylamide as lattice agent. The gel and the products after calcining were characterized by TG-DSC, FT-IR, XRD, TEM and wave-guide method. DSC curve indicates that the gel has a strong exothermic peak at 458.8℃. Correspondingly, there is a strong weight loss of 34.5% in the range of 410℃-480℃ by the TG curve. The FT-IR spectra illustrates that the M-O characteristic absorption band is shifted from 541 cm-1 to 563 cm-1 when the calcining temperature is shifted from 500℃ to 700℃. The XRD results show that the dried gel is amorphous phase. And the characteristic peaks of the spinel ZnFe2O4 appear after the gel was annealed at 500℃ for 2h. When the calcining temperature is 500, 600 and 700℃, the average size of grains is identified to be about 15, 35 and 60nm by TEM, respectively. The complex permittivity (ε=ε'-jε''), complex permeability (u=u'-ju'') and microwave absorption properties of zinc ferrite composites prepared with different calcining temperature were investigated in the frequency range of 8.2～12.4GHz, the nanocrystalline ZnFe2O4 has both dielectric loss and magnetic loss. With the increasing of the calcining temperature, the dielectric parameters, dielectric loss, permeability, magnetic loss and reflection loss of the nanocrystalline ZnFe2O4 obviously increase. The prepared composites can fruitfully be utilized for suppression of electromagnetic interference and reduction of radar signatures.