Effect of d-block element substitution on structural and dielectric properties on iron cobaltite

FeCo2O4 and Fe0.5TM0.5Co2O4 (TM = Mn, Cr, Zn and Ni) were prepared by Solid-state reaction route. The influences of the Cr, Mn, Zn and Ni content on the structural and dielectric properties of FeCo2O4 were investigated. X-ray diffraction analysis reveals that the prepared samples are polycrystalline cubic spinel in structure (Fd3m). SEM analysis shows the morphology of Iron cobaltite samples. The vibration modes of samples were analyzed through the Raman spectra. From dielectric measurement, we observed that for all sample the dielectric constant and loss decreases with an increase in frequency and becomes constant at higher frequencies. The ac conductivity (σac) shows normal behavior with frequency, which implies that the samples have high grain boundary resistance at low-frequency. It can be explained on the basis of Maxwell–Wagner model inferring that transition metal doped Fe cobaltites are promising in microwave applications. The hump present in modulus curve indicates conductivity relaxation. In FeCo2O4 and Fe0.5Zn0.5Co2O4 cobaltite, Cole-Cole plot of electric modulus shows only one semicircle, signifying the capacitive and resistive properties of the materials; as a result of contribution of grain boundaries. •FeCo2O4 and Fe0.5TM0.5Co2O4 (TM = Mn, Cr, Zn and Ni) samples synthesized by solid-state reaction route successfully.•XRD confirms cubic spinel structure with space group Fd3m structure with Fe2O3 secondary phase.•Five vibration modes were analyzed through the Raman spectra.•Dielectric measurement confirms, the materials have high dielectric constant with low losses.