Improved electrical and dielectric properties of La-doped Co ferrite

We report on the enhanced dielectric constant and electrical resistivity of the Co-ferrite (CoO.Fe2O3) by partially substituting Fe with La. Structural characteristics of La-doped Co ferrite namely CoO.Fe1.925La0.075O3indicate the cubic inverse spinel phase with a small amount of LaFeO3additional phase. The lattice parameter obtained is 8.401 Å (±0.001 Å), which is higher than that reported for Co ferrite (8.387 Å, ±0.001 Å). The dielectric constant and electrical resistivity of CoO.Fe1.925La0.075O3are higher compared with pure Co ferrite. The dielectric constant dispersion of CoO.Fe1.925La0.075O3in the frequency range of 100 Hz to 1 MHz fits to the modified Debye’s function with more than one ion contributing to the relaxation. Temperature-dependent electrical resistivity curves exhibit two distinct regions indicative of two different types of conduction mechanisms. Analysis of the data indicates that the small polaron and variable-range hopping mechanisms are operative in the 220 to 300 K and 160 to 220 K temperature regions, respectively.