Abstract: Ferrites are technologically useful materials due to their unique electric and dielectric properties. The co-substitution of metal ions in nickel ferrites are one of the most attractive classes of materials for researchers and scientist. NiAl2xCrxFe2-3xO4 (0.0 ? x ? 0.2) spinel ferrite nanoparticles were synthesized by sol-gel auto combustion method. The DC electrical resistivity of prepared nanoparticles was studied using two probe methods as a function of temperature. The dielectric parameters such as dielectric constant (?'), dielectric loss (??) and loss tangent (tan d) were measured at room temperature in the frequency range 50 Hz to 5 MHz. All the dielectrical parameters show compositional as a function of frequency dependences. At lower frequencies, it is observed that the dielectric constant (?'), dielectric loss (?) and loss tangent (tan d) are high.

Keywords: Activation energy; nanoparticles; Dielectric properties.