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Title: Pressure effect on the electronic structure of iron in (Mg,Fe)(Al,Si)O3 perovskite: A combined synchrotron M?ssbauer and x-ray emission spectroscopy study up to 100 GPa

Abstract

We investigated the valence and spin state of iron in an Al-bearing ferromagnesian silicate perovskite sample, (Mg{sub 0.88}Fe{sub 0.09})(Si{sub 0.94}Al{sub 0.10})O{sub 3}, at 300 K and up to 100 GPa, using diamond-anvil cells and synchrotron Moessbauer spectroscopy techniques. Under elevated pressures, our Moessbauer time spectra are sufficiently fitted by a ''three-doublet'' model, which assumes two ferrous (Fe{sup 2+}) iron types and one ferric (Fe{sup 3+}) iron type with distinct hyperfine parameters. At pressures above 20 GPa, the fraction of the ferric iron, Fe{sup 3+}/{Sigma}Fe, is about 75% and remains unchanged to the highest pressure, indicating a fixed valence state of iron within this pressure range. Between 20 and 100 GPa, the quadruple splittings of all three iron types do not change with pressure, while the isomer shift between the Fe{sup 3+} types and the Fe{sup 2+} type increases continuously with increasing pressure. In conjunction with previous x-ray emission data on the same sample, the unchanging quadruple splittings and increasing isomer shift suggest that Fe{sup 2+} undergoes a broad spin crossover towards the low-spin state at 100 GPa, while Fe{sup 3+} remains in the high-spin state. The essentially constant quadruple splittings of Fe{sup 2+} can also be taken as an indicationmore » for strong resistance against further distortion of the local iron environment after initial compression.« less

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
898500
Report Number(s):
UCRL-JRNL-218577
TRN: US0701667
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Journal Article
Journal Name:
Physics and Chemistry Minerals, vol. 33, no. 8-9, September 5, 2006, pp. 575-585
Additional Journal Information:
Journal Name: Physics and Chemistry Minerals, vol. 33, no. 8-9, September 5, 2006, pp. 575-585
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; 58 GEOSCIENCES; COMPRESSION; ELECTRONIC STRUCTURE; EMISSION SPECTROSCOPY; HIGH SPIN STATES; IRON; ISOMER SHIFT; MOESSBAUER EFFECT; PEROVSKITE; PRESSURE DEPENDENCE; PRESSURE RANGE; SILICATES; SPECTRA; SPIN; SYNCHROTRONS; VALENCE

Citation Formats

Li, J, Sturhahn, W, Jackson, J, Struzhkin, V V, Lin, J F, Zhao, J, Mao, H K, and Shen, G. Pressure effect on the electronic structure of iron in (Mg,Fe)(Al,Si)O3 perovskite: A combined synchrotron M?ssbauer and x-ray emission spectroscopy study up to 100 GPa. United States: N. p., 2006. Web. doi:10.1007/s00269-006-0105-y.
Li, J, Sturhahn, W, Jackson, J, Struzhkin, V V, Lin, J F, Zhao, J, Mao, H K, & Shen, G. Pressure effect on the electronic structure of iron in (Mg,Fe)(Al,Si)O3 perovskite: A combined synchrotron M?ssbauer and x-ray emission spectroscopy study up to 100 GPa. United States. https://doi.org/10.1007/s00269-006-0105-y
Li, J, Sturhahn, W, Jackson, J, Struzhkin, V V, Lin, J F, Zhao, J, Mao, H K, and Shen, G. 2006. "Pressure effect on the electronic structure of iron in (Mg,Fe)(Al,Si)O3 perovskite: A combined synchrotron M?ssbauer and x-ray emission spectroscopy study up to 100 GPa". United States. https://doi.org/10.1007/s00269-006-0105-y. https://www.osti.gov/servlets/purl/898500.
@article{osti_898500,
title = {Pressure effect on the electronic structure of iron in (Mg,Fe)(Al,Si)O3 perovskite: A combined synchrotron M?ssbauer and x-ray emission spectroscopy study up to 100 GPa},
author = {Li, J and Sturhahn, W and Jackson, J and Struzhkin, V V and Lin, J F and Zhao, J and Mao, H K and Shen, G},
abstractNote = {We investigated the valence and spin state of iron in an Al-bearing ferromagnesian silicate perovskite sample, (Mg{sub 0.88}Fe{sub 0.09})(Si{sub 0.94}Al{sub 0.10})O{sub 3}, at 300 K and up to 100 GPa, using diamond-anvil cells and synchrotron Moessbauer spectroscopy techniques. Under elevated pressures, our Moessbauer time spectra are sufficiently fitted by a ''three-doublet'' model, which assumes two ferrous (Fe{sup 2+}) iron types and one ferric (Fe{sup 3+}) iron type with distinct hyperfine parameters. At pressures above 20 GPa, the fraction of the ferric iron, Fe{sup 3+}/{Sigma}Fe, is about 75% and remains unchanged to the highest pressure, indicating a fixed valence state of iron within this pressure range. Between 20 and 100 GPa, the quadruple splittings of all three iron types do not change with pressure, while the isomer shift between the Fe{sup 3+} types and the Fe{sup 2+} type increases continuously with increasing pressure. In conjunction with previous x-ray emission data on the same sample, the unchanging quadruple splittings and increasing isomer shift suggest that Fe{sup 2+} undergoes a broad spin crossover towards the low-spin state at 100 GPa, while Fe{sup 3+} remains in the high-spin state. The essentially constant quadruple splittings of Fe{sup 2+} can also be taken as an indication for strong resistance against further distortion of the local iron environment after initial compression.},
doi = {10.1007/s00269-006-0105-y},
url = {https://www.osti.gov/biblio/898500}, journal = {Physics and Chemistry Minerals, vol. 33, no. 8-9, September 5, 2006, pp. 575-585},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 23 00:00:00 EST 2006},
month = {Mon Jan 23 00:00:00 EST 2006}
}

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