Studies on structural and electrical properties of Co1−xNixFe1.9Mn0.1O4 ferrite

Nickel-doped iron-deficient cobalt ferrite with small amount of manganese having the chemical composition Co_1−xNi_xFe_1.9Mn_0.1O₄, with x = 0.2, 0.4, 0.6 and 0.8, were prepared by standard double sintering ceramic method. The spinel phase formation was confirmed by X-ray diffraction (XRD). The DC resistivity measurements with temperature indicate a semiconducting behavior showing a linear decrease with increasing temperature and the doping of Ni enhances the resistivity. Maximum resistivity of the order of 10⁹ Ω cm was found for composition x = 0.8. Room temperature dielectric constant measurements with frequency (100 Hz to 1 MHz), show usual dielectric dispersion. Also, the variation of room temperature AC conductivity as a function of frequency were studied and explained by using Maxwell–Wagner two-layer model. The studies on dielectric constant (′), loss tangent (tan δ) and AC conductivity (σ_AC), at four different frequencies (viz., 1, 10, 100 kHz and 1 MHz), with temperature were made.