Effect of Mn and La Doping on the Structural, Morphological and Magnetic Properties of Cobalt Ferrite

ABSTRACT

The present investigation establishes a relationship between lattice distortion, cation distribution, and magnetic properties, and proves that Mn ^{2 +} /La ^{3 +} co‐substitution is an efficient route to tailor the structural and magnetic properties of cobalt ferrites. Co _{1 − 2x} Mn _x La _x Fe ₂ O ₄ (x = 0.00 to 0.10) nanoparticles were synthesized via the sol–gel auto‐combustion route to investigate the effect of Mn ^{2 +} and La ^{3 +} co‐substitution on the structural, morphological, and magnetic properties of cobalt ferrite. XRD patterns reveal a single cubic spinel phase for all samples. FTIR spectra show the typical metal‐oxygen bands for both tetrahedral and octahedral sites, confirming the spinel structure and exhibiting small band shifts due to cation substitution and lattice distortions. FESEM images reveal a nanoscale particle size with an agglomerated structure, and grain refinement at lower doping concentrations. Room temperature VSM analysis confirms ferrimagnetic behavior for all samples. The saturation magnetization increases from 82.63 to 87.34 emu/g at x = 0.02 due to enhanced magnetic contribution from Mn ^{2 +} at the B‐site, followed by a decrease at higher Mn/La doping levels due to magnetic dilution from non‐magnetic La ^{3 +} ions and spin canting effects. Coercivity exhibits a non‐monotonic variation, reaching a maximum at x = 0.02, consistent with increased magneto‐crystalline anisotropy and strain‐induced stress anisotropy.