The electric and dielectric properties of the ZnNi-ferrite plated NiFe microspheres synthesized from aqueous solution

We have performed systematical study of the impedance spectra and dielectric modulus on the Ni-Fe microspheres encapsulated with the ZnNi-ferrite by ultrasonic assisted ferrite plating process. The equivalent electric circuit composed of resistance and capacitance has been utilized in analog of the electrical and dielectric properties of the microspheric composites. The result of analysis implies that the resistive ferrite layer and ZnNi-ferrite/NiFe-spheres interface inhibit the eddy currents path and, thus causing enhancement of the dynamic magnetization. Both temperature and field variation of impedance provide evidence of the tunneling conduction in the microspheric composites, signifying existing of Ferromagnet/Insulator/Ferromagnet (F/I/F) structure.