Mechano-chemical synthesis of stoichiometric nickel and nickel-zinc ferrite powders with Nicolson-Ross analysis of the absorption coefficients

Abstract

The interest in finding new methods for the preparation of nickel ferrite (NiFe 2O 4) and nickel-zinc ferrite (Ni xZn 1-xFe 2O 4) powders has recently increased, because the physical and chemical properties of these soft magnetic materials depend strongly on the preparation conditions. In this study, powder samples of ferrites were obtained by: 1) a classic sintering procedure (Ni xZn 1-xFe 2O 4, x = 0.9) and 2) planetary mill synthesis (both NiFe 2O 4 and the Ni xZn 1-xFe 2O 4). The mechano-chemical reaction leading to the formation of the spinel phase of Ni xZn 1-xFe 2O 4 (x = 1 or 0.9) was monitored by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) analysis. The values of the real and imaginary parts of the permittivity and permeability were measured for the obtained nickel and nickel-zinc ferrite samples in the 7-12 GHz frequency range. Based on the obtained results, the electromagnetic radiation (EMR) absorption coefficients were calculated for all three types of sample. It was concluded that the method of preparation and the final particle size influence the EMR absorption coefficient of nickel and nickel-zinc ferrites. © 2012 Copyright (CC) SCS.