Tuning the magnetic and dielectric properties of Fe3O4 nanoparticles for EMI shielding applications by doping a small amount of Ni2+/Zn2+

Abstract

Magnetite (Fe3O4) nanoparticles have been considered as a promising microwave absorption materials. To further tune their electromagnetic interference shielding efficiency, different compositions of doped Ni0.01-xZnxFe2.99O4 (x = 0.0, 0.005, 0.01) nanoparticles were synthesized by the co-precipitation technique. The prepared nanoparticles structure was characterized by X-ray diffraction, transmission electron microscopy, and Mossbauer spectroscopy. Impedance spectroscopy and magnetic measurements showed a dramatic enhancement in the dielectric and magnetic properties of Ni2+ doped Fe3O4 among the prepared samples, respectively. This is ascribed to the homogeneous distributed microstructure and considerable Fe2+/Fe3+ ratio at the octahedral sites due to unusual cation redistribution in the Ni0.01Fe2.99O4 nanoparticles. Moreover, the measurements of total shielding efficiency exhibited an improvement of 83% in the shielding effectiveness of Ni0.01Fe2.99O4 (similar to 22 dB) with the absorption dominant mechanism compared to pure Fe3O4 (similar to 12 dB) in the X-band frequency range. This is probably the result of a better impedance matching between the permittivity/permeability and dielectric/magnetic losses.