First-principles investigation on the electronic structure and stability of in-substituted ZnFe₂O₄

The geometric structure, electronic structure, and stability of In-substituted ZnFe₂O₄ (Zn₇InFe ₁₆O₃₂ 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 Zn₇InFe₁₆O ₃₂ is easier to be formed than Zn₈Fe₁₅InO ₃₂. In substitution changes the properties of ZnFe₂O ₄ from semiconducting character to metallic character. For ZnFe ₂O₄ 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.