Structural and electrical properties of chromium substituted nickel ferrite by conventional ceramic method

Polycrystalline Cr substituted Ni ferrites [NiCr_xFe_2−xO₄ (0.0 ≤ x ≤ 1.0)] were synthesized by conventional ceramic method and sintered at 1350 °C in air. X-ray diffraction (XRD) patterns showing sharp peaks confirmed the formation of single phase cubic spinel structure. The lattice parameters of the samples were determined from the XRD data using Nelson-Riley extrapolation technique. They were found to decrease with increasing Cr concentration obeying Vegard’s law. X-ray density, bulk density and porosity were also calculated from the XRD data. The variation of DC resistivity with temperature was measured by two-probe method. The DC resistivity was found to decrease with increasing temperature indicating the semiconducting nature of the samples. Activation energy was calculated from the Arrhenius plot. AC resistivity, dielectric constant and loss tangent were measured in the frequency range of 1 kHz to 120 MHz at room temperature.