الفهرس 
Chapter 1 IntroductionOnly 14 pages are availabe for public view
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Abstract
This thesis involves a new technique for the preparation of nanometal oxide namely Co3O4. This method is safe, low cost and gives a pure crystal of the metal oxide with grain size in the range of a nanometer. This method depends on co-precipitation technique for the preparation of nano-material. The new technique here is that we subject the preparation path to high frequency ac sin wave with amplitude 9V wave and two aluminum plates are fixed on the opposite wall as electrodes attached to the poles of the signal generators. To optimize the most suitable condition for the preparation we used different frequencies, concentration of Co3O4 and path volume. Different techniques have been used to determine and characterize the prepared samples, such as IR, UV- visible spectral analysis. To determine the crystal size, XRD pattern were used. In addition, the effect of size on the physical properties such as alternating current electrical conductivity σac and dielectric constant έ at different temperatures and frequencies were studied for the prepared samples. IR spectral analysis ensures the formation of cubic spinels structure of Co3O4 with two bands of high intensity in the range of 550-690 cm-1. The optical energy gaps Eopt for the prepared samples were calculated by using Mott and Davis equation. It is found that its values also depend on the condition of preparation (frequency and concentration). XRD-patterns also reveal the formation of cubic spinels structure. Also it is found that the particle size of the prepared samples decreases with the increase in frequency of the applied signal and also decrease with increase of the reaction path volume. Otherwise, TEM images prove the formation of nano-grain with spherical shape with 50-90 nm size range.
The Ac-electrical conductivity σac was studied at various temperatures and frequencies. It was found that σac follows the power law equation with s values range 0-1 depending on the preparation conditions and these values indicates that the conduction of the prepared samples goes through hopping conduction mechanism.
The dielectric constant έ showed very high values and also depend on the preparation conditions. We can conclude from these results that as the frequency and the concentration of the prepared materials decreased we can get semiconductor materials with very high values of dielectric constant at both radio and microwave frequencies. The present results may make it as a promising candidate for energy storage in electronic application.