Investigating the structural, magnetic, and electrical transport properties of mesoporous Ni-ferrite nanoparticles using Mott’s VRH model and Jonscher’s power law

Mn-substituted Ni ferrite nanoparticles (NM FNPs) (Ni 1−x Mn x Fe 2 O 4 : X = 0.5, 0.7, 0.9) were synthesized via auto-combustion method and the morphological, structural, electrical, and magnetic properties were systematically investigated. XRD and Rietveld refinement confirmed the formation of a cubic spinel structure, with crystallite sizes ranging from 25.1 to 97.6 nm. SEM images revealed notable agglomerated nanoparticles and BET analyses indicated mesoporous characteristics. Electrical studies confirmed the thermally activated semiconducting behaviour, governed by polaron hopping. AC conductivity followed Jonscher’s power law fit with conductivity 4.49 \(\:\times\:\) 10 −5 S cm − 1 at 453 K for X = 0.5. The DC conductivity is explained using Mott’s Variable Range Hopping (VRH) model and Arrhenius conduction. Impedance and Nyquist analyses further confirmed the effects of grains and grain boundaries on conductivity. The magnetic behavior of the nanoparticles is influenced by the concentration of Mn. Incremental doping results in a decrease in coercivity and magnetic saturation, suggesting that the particles exhibit characteristics of soft ferromagnetism and single-domain structures. X = 0.5 exhibits magnetic and electrical properties, making it suitable for advanced electronic and multifunctional applications.