Insights into the Fe(3+) Doping Effects on the Structure and Electron Distribution of Cr(2)O(3) Nanoparticles

Herein, we carefully investigated the Fe(3+) doping effects on the structure and electron distribution of Cr(2)O(3) nanoparticles using X-ray diffraction analysis (XRD), maximum entropy method (MEM), and density functional theory (DFT) calculations. We showed that increasing the Fe doping induces an enlargement in the axial ratio of c/a, which is associated with an anisotropic expansion of the unit cell. We found that as Fe(3+) replaces Cr in the Cr(2)O(3) lattice, it caused a higher interaction between the metal 3d states and the oxygen 2p states, which led to a slight increase in the Cr/Fe–O1 bond length followed by an opposite effect for the Cr/Fe–O2 bonds. Our results also suggest that the excitations characterize a well-localized bandgap region from occupied Cr d to unoccupied Fe d states. The Cr(2)O(3) and Fe-doped Cr(2)O(3) nanoparticles behave as Mott–Hubbard insulators due to their band gap being in the d−d gap, and Cr 3d orbitals dominate the conduction band. These findings suggest that the magnitude and the character of the electronic density near the O atom bonds in Cr(2)O(3) nanoparticles are modulated by the Cr–Cr distances until its stabilization at the induced quasi-equilibrium of the Cr(2)O(3) lattice when the Fe(3+) doping values reaches the saturation level range.