The Effect of Cation Distribution on Initial Permeability and Dynamic Magnetic Properties of Ni0.5(Zn1-xMgx/2Cux/2)0.5Fe2O4 Ferrites

Ferrites with the formula Ni-0.5(Zn1-xMgx/2Cux/2)(0.5)Fe2O4, where x ranges from 0.0 to 0.8 with a step of 0.4, were prepared via the auto combustion method. The structure and chemical composition of the ferrites were analyzed using x-ray diffraction (XRD) and energy dispersive x-ray spectroscopy, respectively. The presence of peaks in the XRD patterns was confirmed by the formation of a cubic spinel structure, because the main peaks of the patterns were related to the single-phase cubic spinel structure with PDF-number of 008-0234. The XRD patterns showed a slight shifting in peaks position due to unstable spacing values with increasing Mg2+, Zn2+ and Cu2+ contents in all ferrites. The mean crystallite size and lattice constant were determined from the Scherer's formula and XRD data. They were found to have been increased by the increase of x concentration. Field emission scanning electron microscopy images were used to analyze the ferrites' structures. In addition, room temperature magnetization and coercivity of ferrites were determined from the hysteresis loops in a magnetic field of 9 kOe by alternative gradient force magnetometer. It was found that the magnetization and coercivity of ferrites with increasing x contents were increased, which is discussed according to the site's occupation of the substituted cations on the sub-lattices. Among all synthesized ferrites, Ni-0.5(Zn1-xMgx/2Cux/2)(0.5)Fe2O4 with x = 0.8 showed the highest magnetization and coercively, whereas Ni-0.5(Zn1-xMgx/2Cux/2)(0.5)Fe2O4 with x = 0.0 displayed the lowest corresponding values. The initial permeability of ferrites as a function of frequency were measured over a frequency range of 10 kHz to 10 MHz. In all curves, the initial permeability remained almost constant during increasing frequency until similar to 1 MH,z and then it fell rapidly. This constant trend of the initial permeability shows the high operating frequency of the ferrites.