Study of structural, dielectric, and optical properties of Ni_0.4Cu_0.4Co_0.2Fe₂O₄ spinel ferrite for electrical and optical applications

The structural, dielectric and optical properties for Ni_0.4Cu_0.4Co_0.2Fe₂O₄ spinel ferrite prepared by sol–gel method have been investigated in this work. The structural analysis for the sample reveals its crystallization in the cubic spinel structure (Fd3 ¯ m space group). The Z"(f) curve confirms the appearance of a relaxation phenomenon in the sample which exhibits semiconductor behavior. An electrical circuit consisting of a link of grain and grain boundary elements is used to analyze the Nyquist plots. The behavior of dielectric constants is related to Koop's phenomenological theory and Maxwell–Wagner's interfacial polarization of dielectrics. The Non-overlapping Small Polaron Tunneling is the appropriate model to explain the conduction mechanism for the sample. The estimated activation energies from the dc conductivity and electrical impedance are close implying that the relaxation and conduction processes are caused by the same type of charge carriers. The scaling mechanisms of the conductivity data versus temperature were also investigated by Ghosh and Summerfield approaches. The random barrier model is adopted to adjust the Summerfield scaling approach for the studied sample. Electrical and optical properties show higher electrical resistivity and considerable visible light absorption which makes the prepared Ni_0.4Cu_0.4Co_0.2Fe₂O₄ ferrite suitable candidate for electrical and optical applications.