The Effect of Thickness of the Dead Layer on the Magnetization of Ni0.5−xCoxZn0.5Fe2O4 Ferrite Nanopowders and Determination of Optimal Permeability

• Published in: Journal of superconductivity and novel magnetism 2021-10, Vol.34 (10), p.2699-2708
• Main Authors: Khah, F. Malakouti, Arab, A., Kiani, E.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Condensed Matter Physics; Magnetic Materials; Magnetism; Original Paper; Physics; Physics and Astronomy; Strongly Correlated Systems; Superconductivity
• ISSN: 1557-1939; 1557-1947
• DOI: 10.1007/s10948-021-05976-x

Co-substituted nickel–zinc ferrite nanoparticles according to the formula Ni 0.5− x Co x Zn 0.5 Fe 2 O 4 ( x  = 0.00, 0.25, and 0.50) have been produced by the co-precipitation method. The structural properties of un-calcined samples were analyzed by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The XRD patterns confirmed the single-phase cubic spinel structure of un-calcined samples. The mean crystallite size and the lattice parameter have been determined from Scherrer’s formula and XRD data. The results showed that the lattice parameter increased with the increase in Co concentration. The FE-SEM micrographs showed that the shape of particles was almost spherical and the distribution of particles size was homogeneous. The magnetization of un-calcined and calcined samples at 900 °C have been obtained from the hysteresis loops in a magnetic field of 8 kOe by alternating gradient force magnetometer (AGFM). This feature has been discussed based on the cation distribution in the sublattices and the core–shell model. Also, the thickness of the dead layer was determined based on the magnetization of the un-calcined and calcined samples. It was found that the thickness of the dead layer of the sample with x  = 0.25 is larger than other samples. The permeability of un-calcined ferries was measured over a frequency range of 10 kHz–8 MHz. It was observed that the permeability of all samples was almost stable in the frequency range of 10 kHz–1 MHz and then it fell. The thickness of the dead layer, due to its effect on the magnetization, can be affected by the permeability. Thus, the sample with x  = 0.25, due to the higher permeability than others, can be used in high-frequency applications.