Spin state of ferric iron in MgSiO3 perovskite and its effect on elastic properties

被引：121

作者：

Catalli, Krystle ^{[1
]}

Shim, Sang-Heon ^{[1
]}

Prakapenka, Vitali B. ^{[2
]}

Zhao, Jiyong ^{[3
]}

Sturhahn, Wolfgang

Chow, Paul ^{[4
]}

Xiao, Yuming ^{[4
]}

Liu, Haozhe ^{[4
]}

Cynn, Hyunchae ^{[5
]}

Evans, William J. ^{[5
]}

机构：

[1] MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA

[2] Univ Chicago, GeoSoilEnviroCARS, Argonne Natl Lab, Argonne, IL 60439 USA

[3] Argonne Natl Lab, Sector 3, Adv Photon Source, Argonne, IL 60439 USA

[4] Argonne Natl Lab, HPCAT, Adv Photon Source, Argonne, IL 60439 USA

[5] Lawrence Livermore Natl Lab, Livermore, CA 94550 USA

来源：

EARTH AND PLANETARY SCIENCE LETTERS | 2010年 / 289卷 / 1-2期

关键词：

spin transition; ferric iron; lower mantle; silicate perovskite; elastic properties; EQUATION-OF-STATE; MAGNESIUM-SILICATE PEROVSKITE; RAY-EMISSION SPECTROSCOPY; HIGH-PRESSURE PHASES; THERMOELASTIC PROPERTIES; (MG; FE)SIO3; PEROVSKITE; CRYSTAL-STRUCTURE; POST-PEROVSKITE; MOSSBAUER-SPECTROSCOPY; SYNCHROTRON MOSSBAUER;

D O I：

10.1016/j.epsl.2009.10.029

中图分类号：

P3 [地球物理学]; P59 [地球化学];

学科分类号：

0708 ; 070902 ;

摘要：

Recent studies have indicated that a significant amount of iron in MgSiO3 perovskite (Pv) is Fe3+ (Fe3+/Sigma Fe = 10-60%) due to crystal chemistry effects at high pressure (P) and that Fe3+ is more likely than Fe2+ to undergo a high-spin (HS) to low-spin (LS) transition in Pv in the mantle. We have measured synchrotron Mossbauer spectroscopy (SMS), X-ray emission spectroscopy (XES), and X-ray diffraction (XRD) of Pv with all iron in Fe3+ in the laser-heated diamond-anvil cell to over 100 GPa. Fe3+ increases the anisotropy of the Pv unit cell, whereas Fe2+ decreases it. In Pv synthesized above 50GPa, Fe3+ enters into both the dodecahedral (A) and octahedral (B) sites approximately equally, suggesting charge coupled substitution. Combining SMS and XES, we found that the LS population in the B site gradually increases with pressure up to 50-60 GPa where all Fe3+ in the B site becomes LS, while Fe3+ in the A site remains HS to at least 136 GPa. Fe3+ makes Pv more compressible than Mg-endmember below 50 GPa because of the gradual spin transition in the B site together with lattice compression. The completion of the spin transition at 50-60 GPa increases bulk modulus with no associated change in density. This elasticity change can be a useful seismic probe for investigating compositional heterogeneities associated with Fe3+. (C) 2009 Elsevier B.V. All rights reserved.

引用

页码：68 / 75

页数：8