Effect of coordination environment on the localization behavior and band tail states of Zn0.7In0.3Fe2O4 and Zn0.3In0.7Fe2O4 nanoparticles

Abstract

The interplay of the coordination environment and localization behavior in ferrites is one of the fascinating and least discussed problems. We report on the effect of the coordination environment on the localization behavior, band tail states, and the optical constants in the UV–Vis regime. X-ray diffraction data confirm the spinal structure with general formula AB2O4. Mossbauer spectroscopy data confirm the existence of Fe ion in the + 3 oxidation state occupying both the tetrahedral and octahedral positions. The Indium (In3+) ions prefer to reside in the tetrahedral A-site. Incorporation of excess In3+ ions causes excess migration of Fe+3 ions to the octahedral B-site and results in the t2g orbital splitting. This lowers the octahedral symmetry from FeO6 to FeO5 dominant coordination environment, which has a strong impact on the magnetic and optical behavior. UV–Vis diffuse reflectance spectroscopy was employed to determine the bandgap and band tail states, which are the key parameters in understanding the localization behavior.