Structural, optical, and dielectric properties for Mg_0·6Cu_0·2Ni_0·2Cr₂O₄ chromite spinel

In this work, the structural, optical, and dielectric properties for Mg_0·6Cu_0·2Ni_0·2Cr₂O₄ chromite sample prepared by sol-gel process were investigated. The XRD characterization for this sample confirmed the development of the face-centered cubic spinel structure with Fd3‾m space group. From the UV–Vis optical absorbance, the synthesized chromite shows significantly lower direct band gap energy and has an appropriate absorption rate in the visible light region. The variations of penetration depth, extinction coefficient, refractive coefficient, dispersion energy parameters, and dielectric permittivity constants were also interpreted. The Non-Overlapping Small Polaron Tunneling (NSPT) and the Correlated Barrier Hopping (CBH) are the suitable models to describe the conduction process for the prepared sample. The behavior of dielectric constants has been interpreted based on the Maxwell-Wagner's theory of interfacial polarization. The behavior of imaginary part of impedance (Z″) shows a dielectric-relaxation phenomenon in the sample with activation energies near to those determined from the conductivity study.