Mechanochemical synthesis of stoichiometric nickel and nickel-zinc ferrite powders with Nicolson-Ross analysis of absorption coefficients

Abstract

The interest in finding new methods for preparation of nickel ferrite (NiFe2O4) and nickel-zinc ferrite (NixZn1-xFe2O4) powders has recently increased, due to the fact that physical and chemical properties of these soft magnetic materials depend strongly on the preparation conditions. In this paper, powder samples of ferrites were obtained by: 1) classic sintering procedure (NixZn1-xFe2O4, x = 0.9) and 2) planetary mill synthesis (both NiFe2O4 and NixZn1-xFe2O4). Mechanochemical reaction leading to the formation of NixZn1-xFe2O4 (x = 1 and 0.9) spinel phase was monitored by SEM, TEM, and XRD. Values of the real and imaginary parts of 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 EMR absorption coefficients were calculated for all three sample types. It has been concluded that the method of preparation and the final particle size influence the EMR absorption coefficient of nickel and nickel-zinc ferrites.