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Abstract
Ferrites are interesting materials from the academic point of view. Also according to the technical point of view, ferrites are involved in many industrial applications. Ferrites properties can be adjusted and strongly changed according to many parameters and conditions. Such conditions which might affect ferrite properties are, methodology used in synthesis, heat treatment, constituents and structure.
Cu1-x Nix Fe2O4 ferrite system was synthesized for X = 0.0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0 utilizing the standard double sintering ceramic technique. From the X-ray investigation the structure of the ferrite was determined and found to be cube structure for all values of X. Besides, the lattice constants of the composition were precisely estimated and found to verify Vegard’s law.
Cation distribution of the form (CuyFez-y) [Cu1-x-yNixFe2-z+y] O42- was predicted and tried employing two different independent techniques. A comparison between the experimental lattice constant and calculated lattice constant taken from the predicted cation distribution seems to be reasonable. Intensity of X-ray diffraction pattern was calculated, regarding the cation distribution, and compared with the experimental one indicates the validity of the cation distribution x, y and z parameters. In account of the structural analysis, microstructural properties such as crystallite size were estimated regarding best fit peak profile. In order to elucidate the interionic structure the interionic distances such as AO, BO, ra, rb and hopping length were also estimated and compared with the IR spectrometry investigation. According to IR study of Cu Ni ferrite, it has been found that the octahedral B-site and tetrahedral A-site are pronounced and absorption band were detected corresponding to these sublattices. Contributions of each sublattice to the force constant Kt and Ko have been evaluated for the studied ferrite.
Concerning the electrical properties of Cu1-x Nix Fe2O4 ferrite, the DC conductivity was measured at room and elevated temperatures up to ~ 800 K. Structural and magnetic transitions were manifested in the DC measurements. According to the magnetic transition, the corresponding Curie temperature Tc for each composition was revealed. In addition, the activation energy E before and after transition has also been estimated. Parameters as relaxation time , hopping jump frequency wh and frequency exponent factor S were revealed from the AC conductivity measurements in the frequency range between 0MHz up to 5MHz over the whole range of temperature. According to the value of S and its temperature and frequency dependence the conduction mechanism coincides with the correlated-barrier hopping CBH.
For technical applications, the dielectric properties of Cu1-x Nix Fe2O4 ferrite system were scrutinized throughout this study. Dispersive trend was detected in the frequency dependence of the dielectric constant `, in the low frequency region. Such dispersion is consistent with Maxwell-Wagner interfacial polarization. Moreover, the dielectric loss `` and loss tan were also determined over the whole studied range of temperature and frequency. As a magnetic property, the initial permeability μi of Cu1-x Nix Fe2O4 ferrite system was detected at different temperatures. Anomalous trend was observed in the temperature dependence of μi near Curie temperature Tc. Good agreement between Tc deduced from AC, DC measurements and that taken from μi data was detected for the studied ferrite.