First-Principles Investigation on the Electronic Structure and Stability of In-Substituted ZnFe₂O₄

The geometric structure, electronic structure, and stability of In-substituted ZnFe₂O₄ (Zn₇InFe₁₆O₃₂ and Zn₈Fe₁₅InO₃₂) are investigated by the density functional theory at generalized gradient approximation level. Compared with the perfect ZnFe₂O₄ (Zn₈Fe₁₆O₃₂), the unit cell volume of In-substituted ZnFe₂O₄ increases and the structure deforms slightly. The formation energy of In substitution for Zn is smaller than that of In substitution for Fe, indicating that Zn₇InFe₁₆O₃₂ is easier to be formed than Zn₈Fe₁₅InO₃₂. In substitution changes the properties of ZnFe₂O₄ from semiconducting character to metallic character. For ZnFe₂O₄ and In-substituted ZnFe₂O₄, the strength of O–Zn bond is stronger than O–Fe bond and both of them have a covalent bond character. The strength of O-In bond is similar to that of O–Zn bond in Zn₇InFe₁₆O₃₂, but weaker than O–Fe in Zn₈Fe₁₅InO₃₂. In substitution for Zn causes the strength of O–Fe bonds around In atom to weaken. In substitution for Fe causes the strength of O–Zn bonds around In atom to weaken obviously, while the strength of O–Fe bonds strengthen slightly.