Asghari Maqsood
Ferrites which are ferrimagnetic ceramic materials have different metal oxides converged with iron (Fe3+) to form their core segment. Ferrites are of two kinds, soft and hard. Soft materials are used for electromagnets because they are simply magnetized and demagnetized. On the other hand, hard materials are hard to magnetize and demagnetize, so they are used for permanent magnets. The core properties of ferrites depend on composition, synthesis techniques, temperature, cation distribution and the particle size. Although iron and metallic alloys are scientifically useful as magnetic materials, these materials are impractical because of low resistivity at high frequency. Because of high electrical resistivity of these ferrites, these are superior at high frequencies. In this talk, the fabrication of Cr doped Ni0.5-Zn0.5CrxFe2-xO4 (0.1≤x≤0.4) is reported. The material was characterized by x-ray diffraction technique to get the information related to structure, average crystallite size, x-ray density, porosity, the specific surface area and surface to volume ratio as shown in the Fig. The variation of electrical parameters like DC electrical resistivity and mobility as a function of temperature was investigated in the range of 435 to 770 K. The activation energies of all the samples were calculated from the DC electrical resistivity data. The dielectric parameters such as dielectric constant (ε ), dielectric loss (tanα) and AC conductivity (αac) are measured in the temperature range of 300 to 770 K. It was observed that the dielectric constant was found to increase with the Cr3+ concentration, while tanα and αac decreased. The results are explained on the basis of increase in interfacial and dipolar polarization in the samples. Transition temperatures obtained from dielectric constant are in agreement with Curie temperatures, obtained from resistivity plots.
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