Structural, morphological and magnetic properties of Al3+ substituted Ni0.25Cu0.20Zn0.55AlxFe2−xO4 ferrites synthesized by solid state reaction route

Ni-Cu-Zn ferrite materials have been extensively used in electronic materials because of their outstanding properties at high frequencies. This work investigates the impact of Al substitution on the structure, morphology and magnetic properties of Ni0.25Cu0.20Zn0.55AlxFe2−xO4 (x = 0.00, 0.05, 0.10, 0.15 and 0.20) prepared by solid state reaction method. X-ray diffractometer (XRD), field emission scanning electron microscope (FESEM), impedance analyzer and Vibrating Sample Magnetometer (VSM) were used to characterize the properties of the samples. The XRD study confirmed the cubic spinel structure with single phase for all the samples. The lattice constant, X-ray density and bulk density decrease while the porosity and grain size increase with the increase of Al content in the samples. The frequency dependence of the complex permeability sintered at 1200 °C has been measured for toroidal samples in the frequency range between 1 kHz and 120 MHz at room temperature. The decrease in initial permeability has been explained on the basis of variation in grain size. The temperature dependence of the initial permeability has been measured in the temperature range between from 30 to 250 °C. Curie temperature (Tc) has been estimated from the temperature dependence of the permeability spectra for all samples. It is found that Curie temperatures and initial permeability (μi′) decrease on Al substitution. The saturation magnetization has been measured at room temperature and it was found to decrease with increasing of Al3+ ions.