Fe-dopant site occupancy in Co3O4: evidence of isovalent substitution and short-range association at octahedral sites
Year: 2026
Type: preprint
Abstract: Understanding how dopant site occupancy influences the behavior of spinel oxides is essential for tailoring their functional properties. Here, we combine DFT+U calculations with computational and experimental Co K-edge XANES spectroscopy to investigate the structural, electronic, and magnetic effects of Fe incorporation into Co3O4. The results indicate a strong energetic preference for isovalent substitution, with Fe3+ preferentially occupying octahedral Co3+ sites. This preference becomes more pronounced with increasing dopant concentration, leading to a clear stability hierarchy in which short-distance double-octahedral configurations are energetically favored. Dopant–dopant interactions further influence this stability landscape, promoting attractive coupling for octahedral and mixed-site configurations, while tetrahedral Fe3+ exhibits weak or slightly repulsive interactions. These trends are reflected in the magnetic properties, with octahedral Fe inducing stronger local magnetic moments compared to tetrahedral substitution. The calculated XANES spectra reveal site-dependent modifications of the Co pre-edge features that can be related to changes in the local electronic structure induced by Fe doping. However, these spectral changes should be interpreted qualitatively in light of known limitations of the theoretical approach. Overall, this study highlights the central role of dopant site occupancy, in addition to dopant concentration, in tuning the structural, electronic, and magnetic properties of Co3O4 spinels.
Source: ChemRxiv
Institutions: Centre National de la Recherche Scientifique, École Polytechnique, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Institut Rayonnement-Matière de Saclay, Institut Polytechnique de Paris, Marien Ngouabi University, University of South Africa, Max Planck Institute for Chemical Energy Conversion, University of Duisburg-Essen
Language: English
Subfield: Radiation
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7222292915