Enhancement of the magnetic properties of Ni–Cu–Zn ferrites by the non-magnetic Al 3+-ions substitution

Abstract

The effect of Al-substitution on the physical, magnetic and electrical properties of Ni–Cu–Zn ferrite of chemical formula Ni 0.4Cu 0.2Zn 0.4Al x Fe 2− x O 4 ( x = 0 to x = 0.15 with step = 0.025) which prepared by conventional ceramic method has been studied. X-ray patterns indicated the presence of a single spinel phase. Analysis of IR-spectrum indicated the occupation of Al-ions the octahedral site in ferrite lattice. SEM micrographs showed that the average grain size D decreased with increasing Al-content. The magnetization is measured using VSM at room temperature. The initial permeability is measured, on toroidal samples used as transformer cores, as a function of temperature at constant frequency of 10 kHz and Curie temperature ( T c) is determined. It was found that Al-ion substitute improved the magnetization as well as the initial permeability with no considerable effect for it on the value of T c. The dc resistivity is also increased with increasing Al-concentration. Such results are promising ones for the high frequency applications.