الفهرس 
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Abstract
Ferrite nano particles samples (CoFe2O4, CuFe2O4, Co0.5Cu0.5Fe2O4 and MgFe2O4) have been prepared by citrate precursor method. Polyethylene glycol (PEG)/nano-ferrite composites have been prepared by mixing the prepared ferrite nanoparticles with PEG by different percentages. Ferrite samples have been characterized by X-ray diffraction (XRD) to confirm the formation of pure spinel ferrite phase and, transmission electron microscopy (TEM) to ensure that the average particle size is within the nanoscale. Thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC) thermographs of the ferrite samples have been used to ensure the complete formation of pure ferrites at temperatures above 800oC. The ferrites and their composites with PEG, have been investigated by FTIR spectroscopy. The main bands of ferrites and PEG have been clearly displayed in agreement with literature. A systematic shift of the bands has been observed upon adding PEG. The magnetic properties have been performed by using the vibrating sample magnetometer (VSM). where the values of saturation magnetization (Ms), remnant magnetization (Mr) and coercive field (Hc) for pure ferrite and composite samples vary with the presence of different divalent cations, which have different magnetic moment. Whereas, Hc values remain constant as obtained in pure ferrites regardless the ratio of PEG. The obtained values of Hc are comparable with those in literature, which can be used in electromagnetic wave attenuation. The electrical properties of all the samples have been measured. The DC conductivity has been measured as a function of temperature. v In addition, the AC conductivity and the dielectric parameters have been measured as functions of temperature and frequency. It has been found that the DC electrical conductivity changes by replacing the divalent cation in ferrite samples. In addition, the DC conductivity decrease by increasing the ratio of PEG in the composite samples; this is because the conductivity of PEG lower than the pure ferrite. The AC conductivity follows the same trend as the DC conductivity. The Cole-Cole diagram of ferrites represents two semicircles that confirm that the sample in considered as a combination of parallel RC equivalent circuits in series configuration.