Influence of Zn Substitution on the Lattice Geometry and Bond Structure of Co₁₋ₓZnₓFe₂O₄ Thin Films

Thin film Zn²⁺-substituted cobalt ferrites (Co₁₋ₓZnₓFe₂O₄, where 0.00 ≤ x ≤ 1.00) were systematically investigated to understand the structural evolution and modifications introduced by Zn²⁺ substitution. This study places emphasis on quantifying and interpreting variations in key thin-film structural parameters, including lattice constant, unit cell volume, hopping lengths (LA, LB), tetrahedral and octahedral bond lengths (rA, rB), dislocation density, interionic distances (cation–anion and cation–cation), and bond angles (θ₁ to θ₅). With progressive incorporation of Zn²⁺ into the thin films, the lattice constant and unit cell volume increased, confirming lattice expansion due to the larger ionic radius of Zn²⁺. The thin films also exhibited increased hopping lengths and bond lengths, indicating a distortion of the crystal field and a redistribution of cations across tetrahedral and octahedral sites. Furthermore, a decrease in dislocation density revealed an enhancement in thin-film crystallinity as Zn content increased. Subtle variations in interionic distances and bond angles indicated minor yet consistent structural adjustments. Overall, these results highlight the sensitivity of thin-film lattice geometry to compositional changes and underscore the role of structural evolution in tailoring the properties of ferrite based thin films.