Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Spin transition of iron in magnesiowüstite in the Earth's lower mantle

Abstract

Iron is the most abundant transition-metal element in the mantle and therefore plays an important role in the geochemistry and geodynamics of the Earth's interior1,2,3,4,5,6,7,8,9,10,11. Pressure-induced electronic spin transitions of iron occur in magnesiowüstite, silicate perovskite and post-perovskite1,2,3,4,8,10,11. Here we have studied the spin states of iron in magnesiowüstite and the isolated effects of the electronic transitions on the elasticity of magnesiowüstite with in situ X-ray emission spectroscopy and X-ray diffraction to pressures of the lowermost mantle. An observed high-spin to low-spin transition of iron in magnesiowüstite results in an abnormal compressional behaviour between the high-spin and the low-spin states. The high-pressure, low-spin state exhibits a much higher bulk modulus and bulk sound velocity than the low-pressure, high-spin state; the bulk modulus jumps by 35 per cent and bulk sound velocity increases by 15 per cent across the transition in (Mg0.83,Fe0.17)O. Although no significant density change is observed across the electronic transition, the jump in the sound velocities and the bulk modulus across the transition provides an additional explanation for the seismic wave heterogeneity in the lowermost mantle12,13,14,15,16,17,18,19,20,21. The transition also affects current interpretations of the geophysical and geochemical models using extrapolated or calculated thermal equation-of-state data without considering the effects of the electronic transition5,6,22,23.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Representative X-ray emission spectra of Fe-Kβ collected from a single-crystal magnesiowüstite, (Mg 0.75 ,Fe 0.25 )O, in 〈110〉 orientation at high pressures.
Figure 2: Normalized volume of magnesiowüstite, (Mg 0.83 ,Fe 0.17 )O, as a function of pressure at 300 K.
Figure 3: Calculated isothermal bulk modulus and bulk sound velocity as a function of pressure for the high-spin and low-spin states.

Similar content being viewed by others

References

  1. Sherman, D. M. in Structural and Magnetic Phase Transitions in Minerals (eds Ghose, S., Coey, J. M. D. & Salje, E.) 113–118 (Springer, New York, 1988)

    Book  Google Scholar 

  2. Sherman, D. M. The high-pressure electronic structure of magnesiowüstite (Mg,Fe)O: applications to the physics and chemistry of the lower mantle. J. Geophys. Res. 96(B9), 14299–14312 (1991)

    Article  ADS  CAS  Google Scholar 

  3. Sherman, D. M. & Jansen, H. J. F. First-principles predictions of the high-pressure phase transition and electronic structure of FeO: implications for the chemistry of the lower mantle and core. Geophys. Res. Lett. 22, 1001–1004 (1995)

    Article  ADS  CAS  Google Scholar 

  4. Cohen, R. E., Mazin, I. I. & Isaak, D. G. Magnetic collapse in transition metal oxides at high pressure: implications for the Earth. Science 275, 654–657 (1997)

    Article  CAS  Google Scholar 

  5. Mao, H. K., Shen, G. & Hemley, R. J. Multivariable dependence of Fe-Mg partitioning in the lower mantle. Science 278, 2098–2100 (1997)

    Article  ADS  CAS  Google Scholar 

  6. Andrault, D. Evaluation of (Mg,Fe) partitioning between silicate perovskite and magnesiowüstite up to 120 GPa and 2300 K. J. Geophys. Res. 106, 2079–2087 (2001)

    Article  ADS  CAS  Google Scholar 

  7. Kesson, S. E., Fitz Gerald, J. D., O'Neill, H., St, C. & Shelley, J. M. G. Partitioning of iron between magnesian silicate perovskite and magnesiowüstite at about 1 Mbar. Phys. Earth Planet. Inter. 131, 295–310 (2002)

    Article  ADS  CAS  Google Scholar 

  8. Badro, J. et al. Iron partitioning in Earth's mantle: toward a deep lower mantle discontinuity. Science 300, 789–791 (2003)

    Article  ADS  CAS  Google Scholar 

  9. Lin, J. F. et al. Stability of magnesiowüstite in the Earth's lower mantle. Proc. Natl Acad. Sci. USA 100, 4405–4408 (2003)

    Article  ADS  CAS  Google Scholar 

  10. Badro, J. et al. Electronic transitions in perovskite: possible nonconvecting layers in the lower mantle. Science 305, 383–386 (2004)

    Article  ADS  CAS  Google Scholar 

  11. Li, J. et al. Electronic spin state of iron in lower mantle perovskite. Proc. Natl Acad. Sci. USA 101, 14027–14030 (2004)

    Article  ADS  CAS  Google Scholar 

  12. Su, W. J. & Dziewonski, A. M. Simultaneous inversion for 3-D variations in shear and bulk velocity in the mantle. Phys. Earth Planet. Inter. 100, 135–156 (1997)

    Article  ADS  Google Scholar 

  13. Kellogg, L. H., Hager, B. H. & van der Hilst, R. D. Compositional stratification in the deep mantle. Science 283, 1881–1884 (1999)

    Article  ADS  CAS  Google Scholar 

  14. van der Hilst, R. D. & Kárason, H. Compositional heterogeneity in the bottom 1000 kilometers of Earth's mantle: toward a hybrid convection model. Science 283, 1885–1888 (1999)

    Article  ADS  CAS  Google Scholar 

  15. Garnero, E. Heterogeneity of the lowermost mantle. Annu. Rev. Earth Planet. Sci. 28, 509–537 (2000)

    Article  ADS  Google Scholar 

  16. Masters, G., Laske, G., Bolton, H. & Dziewonski, A. M. in Earth's Deep Interior: Mineral Physics and Tomography From the Atomic to the Global Scale (eds Karato, S., Forte, A. M., Liebermann, R. C., Masters, G. & Stixrude, L.) 63–87 (American Geophysical Union, Washington DC, 2000)

    Book  Google Scholar 

  17. Karato, S. I. & Kaiki, B. B. Origin of lateral variation of seismic wave velocities and density in the deep mantle. J. Geophys. Res. 106, 21771–21783 (2001)

    Article  ADS  Google Scholar 

  18. Lay, T., Garnero, E. J. & Williams, Q. Partial melting in a thermo-chemical boundary layer at the base of the mantle. Phys. Earth Planet. Inter. 146, 441–467 (2004)

    Article  ADS  CAS  Google Scholar 

  19. Murakami, M., Hirose, K., Kawamura, K., Sata, N. & Ohishi, Y. Post-perovskite phase transition in MgSiO3 . Science 304, 855–858 (2004)

    Article  ADS  CAS  Google Scholar 

  20. Oganov, A. R. & Ono, S. Theoretical and experimental evidence for a post-perosvkite phase of MgSiO3 in Earth's D″ layer. Nature 430, 445–448 (2004)

    Article  ADS  CAS  Google Scholar 

  21. Tsuchiya, T., Tsuchiya, J., Umemoto, K. & Wentzcovitch, R. M. Elasticity of post-perovskite MgSiO3 . Geophys. Res. Lett. 31, L14603, doi:10.1029/2004GL020278 (2004)

    Article  ADS  Google Scholar 

  22. Jackson, I. Elasticity, composition and temperature of the Earth's lower mantle: a reappraisal. Geophys. J. Int. 134, 291–311 (1998)

    Article  ADS  Google Scholar 

  23. Stacey, F. D. & Isaak, D. G. Compositional constraints on the equation of state and thermal properties of the lower mantle. Geophys. J. Int. 146, 143–154 (2001)

    Article  ADS  Google Scholar 

  24. Jacobsen, S. D. et al. Structure and elasticity of single-crystal (Mg,Fe)O and a new method of generating shear waves for gigahertz ultrasonic interferometry. J. Geophys. Res. 107(B2), 10.1029/2001JB000490 (2002)

  25. Speziale, S., Zha, C. S., Duffy, T. S., Hemley, R. J. & Mao, H. K. Quasi-hydrostatic compression of magnesium oxide to 52 GPa: Implications for the pressure-volume-temperature equation of state. J. Geophys. Res. 106, 515–528 (2001)

    Article  ADS  CAS  Google Scholar 

  26. Holmes, N. C., Moriarty, J. A., Gathers, G. R. & Nellis, W. J. The equation of state of platinum to 660 GPa (6.6 Mbar). J. Appl. Phys. 66, 2962–2967 (1989)

    Article  ADS  CAS  Google Scholar 

  27. Birch, F. Equation of state and thermodynamic parameters of NaCl to 300 kbar in the high-temperature domain. J. Geophys. Res. 91, 4949–4954 (1986)

    Article  ADS  CAS  Google Scholar 

  28. Vinet, P., Ferrante, J., Rose, J. H. & Smith, J. R. Compressibility of solids. J. Geophys. Res. 92, 9319–9325 (1987)

    Article  ADS  CAS  Google Scholar 

  29. Shannon, R. D. & Prewitt, C. T. Effective ionic radii in oxides and fluorides. Acta Crystallogr. B25, 925–946 (1969)

    Article  Google Scholar 

  30. Badro, J. et al. Nature of the high-pressure transition in Fe2O3 hematite. Phys. Rev. Lett. 89, 205504 (2002)

    Article  ADS  Google Scholar 

  31. Burns, R. G. Mineralogical Applications of Crystal Field Theory Ch. 2, 7–43 (Cambridge Univ. Press, Cambridge, 1993)

    Book  Google Scholar 

  32. Brown, J. M. & Shankland, T. J. Thermodynamic parameters in the Earth as determined from seismic profiles. Geophys. J. R. Astron. Soc. 66, 579–596 (1981)

    Article  ADS  Google Scholar 

Download references

Acknowledgements

We thank R. Caracas, R. Cohen, G. Shen, V. Prakapenka, W. Sturhahn, J. M. Jackson, P. Silver, B. Militzer, S. Hardy, C. Prewitt, M. Somayazulu, P. Dera, and Y. Fei for discussions, S. J. Mackwell for help with sample synthesis, HPCAT for the use of the X-ray facilities, and GSECARS, APS, for the use of the Raman system. This work and use of the APS are supported by the US Department of Energy, Basic Energy Sciences, Office of Science and the State of Illinois under HECA. Work at Carnegie was supported by DOE/BES, DOE/NNSA (CDAC), NSF, and the W. M. Keck Foundation.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Jung-Fu Lin.

Ethics declarations

Competing interests

Reprints and permissions information is available at npg.nature.com/reprintsandpermissions. The authors declare no competing financial interests.

Supplementary information

Supplementary Notes

This contains legends for Supplementary Figures S1 and S2, Supplementary Methods and Supplementary References. (DOC 37 kb)

Supplementary Figure S1

Representative X-ray emission spectra of Fe-Kβ in magnesiowüstite [(Mg0.40,Fe0.60)O] at high pressures. (PDF 40 kb)

Supplementary Figure S2

Relative volume of (Mg0.40,Fe0.60)O as a function of pressure at 300 K. (PDF 36 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Lin, JF., Struzhkin, V., Jacobsen, S. et al. Spin transition of iron in magnesiowüstite in the Earth's lower mantle. Nature 436, 377–380 (2005). https://doi.org/10.1038/nature03825

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature03825

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing