Molten Salt Synthesis of Ni0.5Zn0.5Fe2O4 ferrites

In this paper, Ni0.5Zn0.5Fe2O4 ferrite ceramics were produced with Ni0.5Zn0.5Fe2O4 powders prepared by reaction in a molten salt using Fe2O3, NiO and ZnO powders as raw materials. Ni-Zn powders were characterized by X-ray diffraction (XRD). Density and shrinkage in diameter of Ni0.5Zn0.5Fe2O4 ceramics were measured. Microstructures were observed using field emission scanning electron microscopy (FESEM), and magnetic properties were examined by HP4291B impedance analyzer. XRD pattern indicated that the powders synthesized at 900 degrees C for 1h were pure spinel Ni0.5Zn0.5Fe2O4 phase. Via the measurement of density and shrink in diameter, optimal temperature was 1200 degrees C and holding time was 2h, which was in accord with the results concluded from micrographs. FESEM images illustrated that the average grain size increased with increasing holding time, which followed the Ostwald liquid growth mechanism. At lower frequencies, the initial permeability (mu(i)) increased from 86.65 to 183.48 with increasing holding time, while the threshold frequency decreased from 13.3MHz to 8.52MHz, which implied the initial permeability (mu(i)) variation complied with the Snoek law to some extent.