Comprehensive investigation on microstructure, electrical/dielectric and magnetic features of novel equimolar Co_3-4x(Mn_xFe_xNi_xCr_x)O₄ (x = 0.05, 0.10, and 0.15) nanoparticles

The main goal of this study is to understand the influence of Mn, Ni, Fe and Cr multi substitution on structural, dielectric, and magnetic properties of Co₃O₄ nanoparticles (NPs), which have been synthesized via sol-gel synthesis. The results revealed the successfully synthesized multi-substitution spinel oxides through X-ray powder patterns. D_XRD are between 14 and 31 nm. AC conductivity exhibited strong temperature (T) and frequency (f) dependence, reflecting mechanisms dominated by interfacial polarization and polaronic conduction. The dielectric constant demonstrated a Maxwell-Wagner type response, influenced by grain boundary polarization and localized charge carriers. Magnetic measurements revealed the coexistence of ferromagnetic (or ferrimagnetic) and antiferromagnetic (or paramagnetic) contributions, with an enhancement in ferromagnetic behaviour attributed to the non-compensated spins, finite size effects, and higher magnetic moments of dopant ions. The coercivity, magnetization, and remanent magnetization were found to increase with the rise in the concentration of Fe, Mn, Ni, and Cr doping ions.