Microstructure and magnetic properties of Ni-Zn ferrites

Ni-Zn ferrites were prepared in air by using the conventional ceramic powde r methodology. The compositions analysed belong to the type NixZn1-xFe2O4 f errites, with x ranging from 0.3-0.4. Copper wire was coiled round the spec imens, previously pressed to a toroidal shape, to characterize their magnet ic properties as a function of the frequency of the applied electric field. Powder X-ray diffraction, scanning electron microscopy and microanalysis, and the magnetic susceptibility of the ferrites, were studied, indicating t hat the highest permeability is achieved at the composition x=0.3, a result which is correlated to the microstructural characterization. The Curie tem perature was also determined to range from 60-130 degrees C, depending on t he specific composition. (C) 1998 Kluwer Academic Publishers.