PreprintCC BY-NC-NDChemRxiv15 Oct 2026

Fe-dopant site occupancy in Co3O4: evidence of isovalent substitution and short-range association at octahedral sites

D. H. Douma^1,2
D. T. Kinouani¹
A. T. Raji³
Olaf Rüdiger⁴
S. DeBeer⁴
S. Kenmoe⁵
Stephane Kenmoe

5 affiliations

¹Groupe de Simulations Numériques en Magnétisme et Catalyse, Faculté des Sciences et Techniques, Université Marien Ngouabi, B.P. 69, Brazzaville, Congo
²LSI, CNRS, CEA/DRF/IRAMIS, École Polytechnique, Institut Polytechnique de Paris
³Deanery College of Science, Engineering and Technology (CSET, University of South Africa (UNISA-Florida Campus, Corner of Christiaan de Wet Road & Pioneer Avenue, Florida, South Africa, 1709
⁴Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, Muelheim an der Ruhr, 45470
⁵Department of Theoretical Chemistry, University of Duisburg-Essen, Universitaetstr. 2, Essen, Germany, D-45141

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.

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Cite

BibTeX RIS

BibTeX

@misc{douma2026fedopant,
  title = {{Fe-dopant site occupancy in Co3O4: evidence of isovalent substitution and short-range association at octahedral sites}},
  author = {D. H. Douma and D. T. Kinouani and A. T. Raji and Olaf Rüdiger and S. DeBeer and S. Kenmoe and Stephane Kenmoe},
  howpublished = {ChemRxiv},
  year = {2026},
  month = oct,
  doi = {10.26434/chemrxiv.15010515/v1},
  url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010515/v1},
  note = {CC BY-NC-ND},
}

RIS

TY  - UNPB
TI  - Fe-dopant site occupancy in Co3O4: evidence of isovalent substitution and short-range association at octahedral sites
AU  - D. H. Douma
AU  - D. T. Kinouani
AU  - A. T. Raji
AU  - Olaf Rüdiger
AU  - S. DeBeer
AU  - S. Kenmoe
AU  - Stephane Kenmoe
PY  - 2026
DA  - 2026/10/15
PB  - ChemRxiv
DO  - 10.26434/chemrxiv.15010515/v1
UR  - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010515/v1
AB  - 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.
ER  -

Abstract

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