الفهرس 
Theoretical backgroundOnly 14 pages are availabe for public view
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Abstract
English Summery
Nano particles of Spinel ferrites having the chemical composition [Li0.1 (Co1-x Cdx)0.8 Fe2.1 O4]; x=0, 0.2, 0.4, 0.6 and 0.8 were synthesized by two different preparation techniques (the sol-gel method and the sol-gel auto-combustion method). Thus the investigated systems were divided into two series according to the preparation techniques.
1- Series (I): The samples were prepared by sol-gel technique and annealed at 800оC for two hours to have a single phase.
2- Series (II): The samples were prepared by sol-gel auto-combustion technique, where the prepared samples showed a single phase directly.
X-ray diffraction (XRD) analysis showed that all samples have cubic spinel structure. Furthermore, the lattice parameter was calculated. The variation of lattice parameter, with cadmium content, showed nearly constant behavior for series (II), while it increased linearly for series (I). For all synthesized samples the porosity P (%) was found to depend on the cadmium concentration. from transmission electron microscope (TEM), we found that particles of series (II) have a
smaller particle size than that of series (I). An expectation of cation distribution was concluded from the analysis of IR spectra. The saturation magnetization, for both series, increased with increasing Cd concentration. A canting behavior was deduced for higher Cd content such that the canting angles of series (I) are larger than those of series (II). On the other hand, the coercivity decreased, for both series, with increasing Cd2+ ions. Furthermore, the coercivity was greatly affected by the different particle size such that the coercivity of series (I) is lower than that of series (II). Moreover, from the variation of relative permeability with temperature, Curie temperature was deduced. Increasing the cadmium content, in both series, obviously decreased the Curie temperature. The optical energy gap was deduced from diffused reflection spectroscopy (DRS). It was found that the energy gap decreased with increasing the Cd content. The optical energy gap was greatly affected by the particle size and was deduced as direct transition. As an application, the catalytic activity of the samples was measured using Fenton reaction. The samples showed a significant results, such that the catalytic activity of series (II) is higher than that of series (I).