The electronic spin state of iron in perovskite, a major component of Earth's lower mantle, can influence the physical and chemical properties of the mantle. However, previous studies have presented an unclear picture of the spin state of iron in perovskite, with some experiments contradicting computational results.
In a new experiment designed to better control the conditions under which perovskite is synthesized, Grocholski et al. measured the spin state of iron in perovskite. They found the dominant spin state at pressures below 50 gigapascals (7.25 million pounds per square inch) to be high spin but observed a transition to a possible mixed spin state at higher pressures.
These results indicate that perovskite is in a mixed or high spin state at least to 2,000 kilometers (1,242 miles) depth in the mantle, consistent with computational results.
The research appears in the journal Geophysical Research Letters.
Authors include B. Grocholski and S. H. Shim, Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology; W. Sturhahn and J. Zhao, Sector 3, Advanced Photon Source, Argonne National Laboratory; Y. Xiao and P. C. Chow, HPCAT, Advanced Photon Source, Argonne National Laboratory.
- Grocholski et al. Spin and valence states of iron in (Mg0.8Fe0.2)SiO3 perovskite. Geophysical Research Letters, 2009; 36 (24): L24303 DOI: 10.1029/2009GL041262
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