Study of Thermal, Microstructural, Optical, Dielectric, and Magnetic Characterizations of Ni–Fe Spinel Cobaltite for Various Applications

The thermal, structural, composition and morphology, optical, dielectric, and magnetic behaviors for the Ni_0.5Fe_0.5Co₂O₄ spinel cobaltite produced by sol–gel technique were studied in this work. The thermogravimetric analysis was used to investigate the temperature-dependent spinel phase formation of the sample and the percentage weight loss. The sample was well crystallized in the cubic spinel structure (Fd3 ¯ m space group) according to Rietveld refinement of the XRD pattern. By using the UV optical absorbance, it has been shown that the compound revealed significant visible-light absorption. The estimated optical band gap energy was estimated as E_gd = 2.78 eV. The dielectric results reveal that the sample has significantly higher electrical resistivity, making it suitable for microwave device applications. NSPT and CBH are the appropriate models which are used to explain the sample conduction process. The impedance and modulus studies show a dielectric relaxation mechanism in the sample. The interfacial polarization law of Maxwell–Wagner has been used to explain the change in dielectric constants. The Nyquist diagrams are well analyzed using an electrical circuit consisting of a connection of grain and grain-boundary elements. The obtained coercive field from the hysteresis loop is quite low in the present sample which would be suitable for soft magnetic device applications.