الفهرس 
Chapter 1 Theoretical Background and Literature SurveyOnly 14 pages are availabe for public view
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Abstract
In this study, polycrystalline Sr-substituted Co2Y-type hexaferrite powders (Ba2-X SrxCo2Fe12O22; X=(0.00, 0.2, 0.4,0.6,0.8 and 1.0) molar ratios have been purposefully prepared via two wet chemical methods; sol gel auto-combustion (SGA) and co-precipitation (CP) pathways. Moreover, the role of Sr2+ ion substituted for Ba2+ ion on the crystal structures, microstructure, magnetic, and dielectric properties of Co2Y-type hexaferrites was also considered. The main goal is to obtain the sufficient properties of hexaferrite suitable for the hyper frequency applications. Typical, a single Co2Y hexaferrite phase was obtained at relatively lower temperature (1000°C) for 1 h through SGA method whereas it was formed at 1000oC for 2 h using CP strategy. The microstructures of the La-substituted hexaferrites powders exhibited as hexagonal platelet-like structure for each series and the particle size of SGA series was relatively smaller than those for CP series. The magnetic properties were evaluated using vibrating sample magnetometer (VSM), since saturation magnetization (Ms) was pound to increase whilst coercivity (Hc) was decreased by increasing Sr-content. Moreover, it was found that both real ε’ and imaginary (ε”) part of complex permitivity were increased due to the polarization increasing. Finally, with the aid of the complex permeability and the complex permittivity, the materials are correlated to the hyper-frequency applications. The characteristic of hexaferrites plays dominant role on the microwave absorptions. The general accepted parameter which governs the interaction of hexaferrites with electromagnetic wave (EM) is the matching impedance. It was calculated and hence the material reflectivity was demonstrated for the Sr-substituted Co2Y-type hexaferrites over X-band.