Spinel ferrites having conductive grains, resistive interfacial boundaries and relaxation mechanism for possible supercapacitor applications

[Display omitted] •Comparison of theoretical and experimental values of lattice and oxygen positional parameters.•Concentration dependent dielectric properties study at room temperature.•Relaxation phenomenon within the prepared samples and relaxation energy.•Three types of semicircles observed on Nyquist plots along with Bode diagrams.•Conductive/resistive behavior of grains/grain boundaries explained using Cole-Cole plots. Linear increase in crystallite size (16–24 nm) of MnxZn1−xFe2O4 nanostructures and mixed behavior of lattice constant (8.429–8.462 Å) is reported. The system exhibits considerable promise for microwave applications due to its elevated dielectric constants and minimal dispersion losses from 20 Hz to 20 MHz. With x = 0.75, sample is good for energy storage devices like supercapacitors due to large specific surface area (53 m2/g) and dielectric constant. These samples exhibit maximum relaxation times ranging from 1.97 × 10−7 s to 2.43 × 10−4 s, with corresponding relaxation energy values spanning from 159.22 meV to 341 meV for x = 0 and x = 1 samples. The Cole-Cole plots reveal that grains exhibit conductive behavior at lower frequencies, while grain boundaries contribute significantly to the resistive behavior. Additionally, we have introduced Bode diagrams and equivalent electronic circuit models for the first time, offering valuable insights into the electrical behavior of the nanomaterial samples.