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Charge self-regulation upon changing the oxidation state of transition metals in insulators

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Abstract

Transition-metal atoms embedded in an ionic or semiconducting crystal can exist in various oxidation states that have distinct signatures in X-ray photoemission spectroscopy and ‘ionic radii’ which vary with the oxidation state of the atom. These oxidation states are often tacitly associated with a physical ionization of the transition-metal atoms1,2—that is, a literal transfer of charge to or from the atoms. Physical models have been founded on this charge-transfer paradigm3,4,5,6, but first-principles quantum mechanical calculations show only negligible changes in the local transition-metal charge7,8,9,10,11,12 as the oxidation state is altered. Here we explain this peculiar tendency of transition-metal atoms to maintain a constant local charge under external perturbations in terms of an inherent, homeostasis-like negative feedback. We show that signatures of oxidation states and multivalence—such as X-ray photoemission core-level shifts, ionic radii and variations in local magnetization—that have often been interpreted as literal charge transfer3,4,13,14,15,16 are instead a consequence of the negative-feedback charge regulation.

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Figure 1: Energy-level diagrams for TM–host interaction.
Figure 2: Properties of GaAs:TM systems, as functions of stable system charge q.
Figure 3: Properties of Cu2O:Co and MgO:Cr, as functions of stable system charge q.
Figure 4: Integrated charge inside the TM-centred sphere.
Figure 5: Charge density differences.

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References

  1. Wells, A. F. Structural Inorganic Chemistry (Clarendon, Oxford, UK, 1975)

    Google Scholar 

  2. Cotton, F. A. & Wilkinson, G. Advanced Inorganic Chemistry (Wiley, New York, 1988)

    Google Scholar 

  3. Goodenough, J. B. & Rivadulla, F. Bond-length fluctuations in transition-metal oxides. Mod. Phys. Lett. B 22, 1057–1081 (2005)

    Article  ADS  Google Scholar 

  4. Solomon, E. I., Hedman, B., Hodgson, K. O., Dey, A. & Szilagyi, R. K. Ligand K-edge X-ray absorption spectroscopy: covalency of ligand-metal bonds. Coord. Chem. Rev. 249, 97–129 (2005)

    Article  CAS  Google Scholar 

  5. Shannon, R. D. & Prewitt, C. T. Effective ionic radii in oxides and fluorides. Acta Crystallogr. B 25, 925–946 (1969)

    Article  CAS  Google Scholar 

  6. Koster, G., Geballe, T. H. & Moyzhes, B. Charge instabilities in the ionic model of metal oxides: importance of polarization energy. Phys. Rev. B 66, 085109 (2002)

    Article  ADS  Google Scholar 

  7. Zunger, A. & Lindefelt, U. Substitutional 3d impurities in silicon: a self-regulating system. Solid State Commun. 45, 343–346 (1983)

    Article  ADS  CAS  Google Scholar 

  8. Zunger, A. in Solid State Physics Vol. 39 (eds Seitz, F., Turnbull, D. & Ehrenreich, H.) 275–464 (Academic, New York, 1986)

    Google Scholar 

  9. Wolverton, C. & Zunger, A. First-principles prediction of vacancy order-disorder and intercalation battery voltages in Li x CoO2 . Phys. Rev. Lett. 81, 606–609 (1998)

    Article  ADS  CAS  Google Scholar 

  10. Leonov, I., Yaresko, A. N., Antonov, V. N., Korotin, M. A. & Anisimov, V. I. Charge and orbital order in Fe3O4 . Phys. Rev. Lett. 93, 146404 (2004)

    Article  ADS  CAS  Google Scholar 

  11. Jeng, H.-T., Guo, G. Y. & Huang, D. J. Charge-orbital ordering and Verwey transition in magnetite. Phys. Rev. Lett. 93, 156403 (2004)

    Article  ADS  Google Scholar 

  12. Luo, W. et al. Orbital-occupancy versus charge ordering and the strength of electron correlations in electron-doped CaMnO3 . Phys. Rev. Lett. 99, 036402 (2007)

    Article  ADS  Google Scholar 

  13. Ikeda, N. et al. Ferroelectricity from iron valence ordering in the charge-frustrated system LuFe2O4 . Nature 436, 1136–1138 (2005)

    Article  ADS  CAS  Google Scholar 

  14. Angst, M. et al. Charge order with integer iron valence in Fe2OBO3 . Phys. Rev. Lett. 99, 086403 (2007)

    Article  ADS  CAS  Google Scholar 

  15. Shim, J. H. & Lee, S. Coexistence of two different Cr ions by self-doping in half-metallic CrO2 nanorods. Phys. Rev. Lett. 99, 057209 (2007)

    Article  ADS  Google Scholar 

  16. Mazin, I. I. et al. Charge ordering as alternative to Jahn-Teller distortion. Phys. Rev. Lett. 98, 176406 (2007)

    Article  ADS  Google Scholar 

  17. Mahadevan, P., Zunger, A. & Sarma, D. D. Unusual directional dependence of exchange energies in GaAs diluted magnetic semiconductors with Mn: Is the RKKY description relevant? Phys. Rev. Lett. 93, 177201 (2004)

    Article  ADS  Google Scholar 

  18. Clerjaud, B. Transition-metal impurities in III–V compounds. J. Phys. C 18, 3615–3661 (1985)

    Article  ADS  CAS  Google Scholar 

  19. Haldane, F. D. M. & Anderson, P. W. Simple model of multiple charge states of transition-metal impurities in semiconductors. Phys. Rev. B 13, 2553–2559 (1976)

    Article  ADS  CAS  Google Scholar 

  20. Karppinen, M., Asako, I., Motohashi, T. & Yamauchi, H. Oxygen nonstoichiometry and actual Co valence in Na x CoO2–δ . . Phys. Rev. B 71, 092105 (2005)

    Article  ADS  Google Scholar 

  21. Kresse, G. & Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169–11186 (1996)

    Article  ADS  CAS  Google Scholar 

  22. Kresse, G. & Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B 59, 1758–1775 (1999)

    Article  ADS  CAS  Google Scholar 

  23. Persson, C., Zhao, Y. J., Lany, S. & Zunger, A. n-type doping in CuInSe2 and CuGaSe2 . Phys. Rev. B 72, 035211 (2005)

    Article  ADS  Google Scholar 

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Acknowledgements

H.R. thanks G. Trimarchi and J. Chan for discussions and for reading the manuscript. A.Z. thanks P. Mahadevan for interest in the early stages of this problem. This work was funded by the US Department of Energy, Office of Science, under NREL Contract No. DE-AC36-99GO10337.

Author Contributions H.R. carried out the calculations, analysed the results and wrote the paper. S.L. and A.Z. contributed to the design of the study, the analysis of results and the writing of the paper.

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Authors and Affiliations

  1. National Renewable Energy Laboratory, Golden, Colorado 80401, USA ,

    Hannes Raebiger, Stephan Lany & Alex Zunger

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  1. Hannes Raebiger
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  2. Stephan Lany
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  3. Alex Zunger
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Correspondence to Hannes Raebiger or Alex Zunger.

Supplementary information

Supplementary information

The file contains Supplementary Discussion 'A' with a detailed account on how electronic configurations are obtained from ab initio calculation, including Supplementary Figures 1 and 2. and Supplementary Discussion 'B' with a discussion how oxidation states can be identified from level occupation and core shifts, including additional references. (PDF 155 kb)

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Raebiger, H., Lany, S. & Zunger, A. Charge self-regulation upon changing the oxidation state of transition metals in insulators. Nature 453, 763–766 (2008). https://doi.org/10.1038/nature07009

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