Modifications on the Structural, Optical, and Magnetic Properties of Ce‐Doped Ni‐Cu‐Co Spinel Nanoferrites Synthesized by Sol–Gel via Auto‐Combustion Method

ABSTRACT This study investigates the impact of cerium doping on the structural, optical, and magnetic properties of Ni 0.5 Cu 0.2 Co 0.3 Ce x Fe 2 −x O 4 ( x = 0.000, 0.025, 0.050, and 0.075) spinel ferrites synthesized by sol–gel via auto‐combustion method. Characterization results confirm the formation of cubic spinel structures with reduced crystallite sizes and modified lattice parameters upon cerium incorporation. Increased cerium content correlates with enhanced porosity, increased bandgap energies, and a rise in structural disorder. Optical studies reveal peak shifts, broadening, and intensity variations, indicative of modified metal‐oxygen bonds and nonradiative recombination pathways. Magnetic characterization reveals a non‐monotonic evolution of saturation magnetization, magnetic moment with cerium incorporation, reflecting the intricate interplay of cation redistribution, spin–orbit coupling, and lattice strain effects. These trends underscore the sensitive dependence of magnetic behavior on subtle structural modifications induced by rare‐earth doping.