Atomic and Electronic Structures of Co-Doped In₂O₃ from Experiment and Theory

The synthesis and properties of stoichiometric, reduced, and Co-doped In₂O₃ are described in the light of several experimental techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet (UV)-visible spectroscopy, porosimetry, and density functional theory (DFT) methods on appropriate models. DFT-based calculations provide an accurate prediction of the atomic and electronic structure of these systems. The computed lattice parameter is linearly correlated with the experimental result in the Co concentration ranging from 1.0 to 5.0%. For higher Co concentrations, the theoretical-experimental analysis of the results indicates that the dopant is likely to be preferentially present at surface sites. The analysis of the electronic structure supports the experimental assignment of Co²⁺ for the doped material. Experiments and theory find that the presence of Co has a limited effect on the material band gap.