Analysis of Bismuth-Doped Cobalt Ferrite (CoFe₂O₄) Nanomaterials on Structural and Morphological Changes

The inverse spinel ferrite cobalt ferrite (CoFe₂O₄) is well known for its superior mechanical hardness, chemical stability, and magnetic anisotropy. The structural, morphological, magnetic, and dielectric properties of CoFe₂O₄ can be effectively tuned by doping it with bismuth (Bi³⁺). Bi³⁺ breaks the spinel lattice, modifies grain formation mechanisms, introduces microstrain, and modifies particle shape due to its large ionic radius and non-magnetic 6s² configuration. This article offers a methodical examination of how Bi substitution affects the morphological and structural properties of CoFe₂O₄ nanomaterials. With a decreased lattice parameter and crystallite size with Bi doping, X-ray diffraction (XRD) consistently demonstrates the retention of the spinel phase. As the Bi content increases, SEM/TEM investigations show how the shape changes from compact grains to flake-like or spherical nanoparticles. We look closely at oxygen sublattice distortions, micro-strain development, and cation redistribution. Research gaps, possible device uses, and future directions are discussed in the review's conclusion.