الفهرس 
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Abstract
Co-precipitation, a one-way process that uses little energy, was used to create CoLaxFe2-xO4 nanoferrites with x = 0, 0.02, 0.06, 0.1, 0.15, and 0.2. Samples of as-prepared CoLaxFe2-xO4 nanoparticles were annealed for four hours at the annealing temperatures T = 500, 700, 900 and 1100 ºC. This study proved that: the addition of La3+ into the CoLaxFe2-xO4 nanoparticles led to atomic disorder. XRD and FT-IR Spectra proved the complete formation of single phase Spinel structure. TEM images and calculated crystallite size proved that the crystallite and particle sizes were in the nano scale size. The magnetic properties were verified with VSM analysis and this proved that these structures are soft magnetic materials. The IR spectra absorption bands v1, v2, v4, and vT were noticed, and their matching sites and bonds were identified. They demonstrated that the crystal lattice contains Fe2+ and Fe4+. The soft magnetic materials’ narrow hysteretic behavior is exhibited through hysteresis loops. TGA and DTA curves for the as-prepared CoLaxFe2-xO4 nanoparticles, 0.0 ≤ x ≤ 0.2 illustrated the formation and improvement of crystallization of this structural phase at 740 ºC. The measured energy gaps values increase with increasing the La doping. Thermal Neutron Irradiation has affected the crystalline structure as improved with XRD, FT-IR, UV and VSM. DC and AC conductivity showed an increase with T due to their expected semiconducting behavior where, as AC conductivity was increased with frequency too. A dispersion of the dielectric constant ε’ was observed. The dielectric loss tangent tan δ shows a relaxation spectrum with frequency. Dielectric modulus formalism is a good method for studying the polarization effect. The impedance behavior profile for all compositions has been displayed using a complex modulus plot (Cole-Cole diagram). Plots were made depicting the actual component of impedance Z’ change with frequency at various temperatures. It was discovered that when frequency and temperature increased, the value of Z’ dropped. Temperature and frequency led to an increase in the material’s electrical conductivity. Plots showing the imaginary portion of impedance Z” vs the real part Z’ (also known as Nyquist plots) were made at a variety of frequencies and temperatures. Semicircular arcs with decreasing maxima as temperature rises are seen in the impedance spectra.