AC AND DC ELECTRICAL PROPERTIES OF NANOPARTICLE SIZE ALUMINUM SUBSTITUTED COBALT FERRITE

Nano-particle size polycrystalline aluminum substituted cobalt ferrite samples CoFe2-2yAl2yO4 (where y = 0.0, 0.05, 0.15 and 0.25) have been prepared by standard ceramic technique. The lattice constants of the phases are evaluated from x-ray diffraction data. The effects of Al3+ on both AC and DC Electrical properties are studied. DC Electrical resistivity is found to increase with increase of aluminum content. Activation energies in ferromagnetic region are found very less than that of paramagnetic region. The SEM micrograph reveals that an average grain size increases with aluminum content. The dielectric constant ε’, complex permittivity ε” and dielectric loss tangent (tanδ) measured at room temperature as a function of the frequency. The effect of Al3+ ion substitution of cobalt ferrite on the AC electrical resistivity and dielectric properties in frequency range 20 Hz to 1MHz. were studied. The data revealed that ε’ and tanδ increased as the Al3+ ion increased , due to the increase in the number of vacancies at the iron site.