Electrical modulus and dielectric behavior of Cr³⁺ substituted Mg–Zn nanoferrites

The dielectric parameters and ac electrical conductivity of Mg_0.8Zn_0.2Cr_xFe_2−xO₄; (0≤x≤0.025) nanoferrites synthesized citrate–nitrate auto-combustion method were studied using the complex impedance technique in the frequency and temperature ranges 4 Hz–5 MHz and 303–873 K respectively. Hopping of charge carriers plus interfacial polarization could interpret the behaviors of dielectric constant (ε′), dielectric loss tangent (tanδ) and ac electrical conductivity (σ_ac) with frequency, temperatures and composition. The up-normal behavior observed in tanδ trend with temperatures confirms the presence of relaxation loss (dipoles losses). Correlated barrier hopping (CBH) of electron is the conduction mechanism of the investigated nanoferrites. Cole-Cole plots at different temperatures emphasize the main role of grain and grain boundaries in the properties of the investigated nanoferrites. Cr³⁺ substitution can control the dielectric parameters and ac electrical conductivity of Mg-Zn nanoferrites making it candidates for versatile applications. - Highlights: • The composition dependence of ε′, tanδ, and σ_ac showed the same trend. • CBH model is the conduction mechanism of the investigated nanoferrite. • Cole-Cole plots confirmed the role of grain and grain boundaries in our nanoferrites.