Effect of preparation methods on magnetic properties of stoichiometric zinc ferrite

Abstract

Synthesis and processing methods can have a significant influence on the physical properties of spinel zinc ferrite since it can produce microstructures characterized by different microstructural parameter such as the arrangement of the ions, lattice parameter, crystallite size and lattice strains (or microstrain). In this work, it has been evaluated the magnetic properties of samples prepared by ceramic synthesis, sol-gel and a third one provided by a ceramic powder supplier. Later, the synthesized samples have been ball-milled for 50 h and compared with a sample prepared by mechanochemical synthesis during 150 h. X-ray powder diffraction (XRD) analysis, performed in order to understand the relation between microstructure and magnetic properties, showed that these four materials are characterized by different values of the microstructural parameters (lattice constant, inversion degree and crystallite size). It was concluded that cation inversion is the most important parameters that can be effective in the deviation of the magnetic properties of zinc ferrite from the properties of the bulk form. Finally, the magnetization curves for the samples milled for 50 h were very similar to the sample prepared by mechanochemical, as expected from the similar microstructural parameters obtained from their XRD patterns. The inversion degree for these samples varied from 0.56 to 0.61 with saturation magnetization at 5 K around 79.0 emu/g. Although structural and chemical properties of this material can be selected by a proper choice of the preparation method, it is also possible to obtain the same microestructural and magnetic properties by a thermomechanic process, regardless of the synthesis method used.