Equation of state and hyperfine parameters of high-spin bridgmanite in the Earth's lower mantle by synchrotron X-ray diffraction and Mössbauer spectroscopy

Zhu Mao, Fan Wang, Jung Fu Lin, Suyu Fu, Jing Yang, Xiang Wu, Takuo Okuchi, Naotaka Tomioka, Vitali B. Prakapenka, Yuming Xiao, Paul Chow

Research output: Contribution to journalArticle

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Abstract

In this study, we performed synchrotron X-ray diffraction (XRD) and Mössbauer spectroscopy (SMS) measurements on two single-crystal bridgmanite samples [Mg0.94 Fe0.04 2+Fe0.02 3+ Al0.01Si0.99O3 (Bm6) and Mg0.89 Fe0.024 2+Fe0.096 3+ Al0.11Si0.89O3 (Al-Bm11)] to investigate the combined effect of Fe and Al on the hyperfine parameters, lattice parameters, and equation of state (EoS) of bridgmanite up to 130 GPa. Our SMS results show that Fe2+ and Fe3+ in Bm6 and Al-Bm11 are predominantly located in the large pseudo-dodecahedral sites (A-site) at lower-mantle pressures. The observed drastic increase in the hyperfine quadrupole splitting (QS) between 13 and 32 GPa can be associated with an enhanced local distortion of the A-site Fe2+ in Bm6. In contrast to Bm6, the enhanced lattice distortion and the presence of extremely high QS values of Fe2+ are not observed in Al-Bm11 at high pressures. Our results here support the notion that the occurrence of the extremely high QS component of approximately 4 mm/s in bridgmanite is due to the lattice distortion in the high-spin (HS) A-site Fe2+, instead of the occurrence of the intermediate-spin state. Both A-site Fe2+ and Fe3+ in Bm6 and Al-Bm11 remain in the HS state at lower-mantle pressures. Together with XRD results, we present the first experimental evidence that the enhanced lattice distortion of A-site Fe2+ does not cause any detectable variation in the EoS parameters, but is associated with anomalous variations in the bond length, tilting angle, and shear strain in the octahedra of Bm6. Analysis of the obtained EoS parameters of bridgmanite at lower-mantle pressures indicates that the substitution of Fe in bridgmanite will cause an enhanced density and a reduced bulk sound velocity (VΦ), whereas the Al and Fe substitution has a reduced effect on density and a negligible effect on VΦ. These experimental results provide new insight into the correlation between lattice, hyperfine, and EoS parameters of bridgmanite in the Earth's lower mantle.

LanguageEnglish
Pages357-368
Number of pages12
JournalAmerican Mineralogist
Volume102
Issue number2
DOIs
StatePublished - Feb 1 2017

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Mossbauer spectroscopy
lower mantle
Synchrotrons
Equations of state
equation of state
synchrotrons
Earth mantle
equations of state
Earth (planet)
X-ray diffraction
X ray diffraction
Synchronous Meteorological Satellite
diffraction
spectroscopy
quadrupoles
x rays
Substitution reactions
lattice parameters
substitution
occurrences

Keywords

  • Bridgmanite
  • equation of state
  • Fe and Al
  • high spin
  • lattice distortion
  • lower mantle

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

Cite this

Equation of state and hyperfine parameters of high-spin bridgmanite in the Earth's lower mantle by synchrotron X-ray diffraction and Mössbauer spectroscopy. / Mao, Zhu; Wang, Fan; Lin, Jung Fu; Fu, Suyu; Yang, Jing; Wu, Xiang; Okuchi, Takuo; Tomioka, Naotaka; Prakapenka, Vitali B.; Xiao, Yuming; Chow, Paul.

In: American Mineralogist, Vol. 102, No. 2, 01.02.2017, p. 357-368.

Research output: Contribution to journalArticle

Mao, Z, Wang, F, Lin, JF, Fu, S, Yang, J, Wu, X, Okuchi, T, Tomioka, N, Prakapenka, VB, Xiao, Y & Chow, P 2017, 'Equation of state and hyperfine parameters of high-spin bridgmanite in the Earth's lower mantle by synchrotron X-ray diffraction and Mössbauer spectroscopy' American Mineralogist, vol. 102, no. 2, pp. 357-368. DOI: 10.2138/am-2017-5770
Mao, Zhu ; Wang, Fan ; Lin, Jung Fu ; Fu, Suyu ; Yang, Jing ; Wu, Xiang ; Okuchi, Takuo ; Tomioka, Naotaka ; Prakapenka, Vitali B. ; Xiao, Yuming ; Chow, Paul. / Equation of state and hyperfine parameters of high-spin bridgmanite in the Earth's lower mantle by synchrotron X-ray diffraction and Mössbauer spectroscopy. In: American Mineralogist. 2017 ; Vol. 102, No. 2. pp. 357-368
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abstract = "In this study, we performed synchrotron X-ray diffraction (XRD) and M{\"o}ssbauer spectroscopy (SMS) measurements on two single-crystal bridgmanite samples [Mg0.94 Fe0.04 2+Fe0.02 3+ Al0.01Si0.99O3 (Bm6) and Mg0.89 Fe0.024 2+Fe0.096 3+ Al0.11Si0.89O3 (Al-Bm11)] to investigate the combined effect of Fe and Al on the hyperfine parameters, lattice parameters, and equation of state (EoS) of bridgmanite up to 130 GPa. Our SMS results show that Fe2+ and Fe3+ in Bm6 and Al-Bm11 are predominantly located in the large pseudo-dodecahedral sites (A-site) at lower-mantle pressures. The observed drastic increase in the hyperfine quadrupole splitting (QS) between 13 and 32 GPa can be associated with an enhanced local distortion of the A-site Fe2+ in Bm6. In contrast to Bm6, the enhanced lattice distortion and the presence of extremely high QS values of Fe2+ are not observed in Al-Bm11 at high pressures. Our results here support the notion that the occurrence of the extremely high QS component of approximately 4 mm/s in bridgmanite is due to the lattice distortion in the high-spin (HS) A-site Fe2+, instead of the occurrence of the intermediate-spin state. Both A-site Fe2+ and Fe3+ in Bm6 and Al-Bm11 remain in the HS state at lower-mantle pressures. Together with XRD results, we present the first experimental evidence that the enhanced lattice distortion of A-site Fe2+ does not cause any detectable variation in the EoS parameters, but is associated with anomalous variations in the bond length, tilting angle, and shear strain in the octahedra of Bm6. Analysis of the obtained EoS parameters of bridgmanite at lower-mantle pressures indicates that the substitution of Fe in bridgmanite will cause an enhanced density and a reduced bulk sound velocity (VΦ), whereas the Al and Fe substitution has a reduced effect on density and a negligible effect on VΦ. These experimental results provide new insight into the correlation between lattice, hyperfine, and EoS parameters of bridgmanite in the Earth's lower mantle.",
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T1 - Equation of state and hyperfine parameters of high-spin bridgmanite in the Earth's lower mantle by synchrotron X-ray diffraction and Mössbauer spectroscopy

AU - Mao,Zhu

AU - Wang,Fan

AU - Lin,Jung Fu

AU - Fu,Suyu

AU - Yang,Jing

AU - Wu,Xiang

AU - Okuchi,Takuo

AU - Tomioka,Naotaka

AU - Prakapenka,Vitali B.

AU - Xiao,Yuming

AU - Chow,Paul

PY - 2017/2/1

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N2 - In this study, we performed synchrotron X-ray diffraction (XRD) and Mössbauer spectroscopy (SMS) measurements on two single-crystal bridgmanite samples [Mg0.94 Fe0.04 2+Fe0.02 3+ Al0.01Si0.99O3 (Bm6) and Mg0.89 Fe0.024 2+Fe0.096 3+ Al0.11Si0.89O3 (Al-Bm11)] to investigate the combined effect of Fe and Al on the hyperfine parameters, lattice parameters, and equation of state (EoS) of bridgmanite up to 130 GPa. Our SMS results show that Fe2+ and Fe3+ in Bm6 and Al-Bm11 are predominantly located in the large pseudo-dodecahedral sites (A-site) at lower-mantle pressures. The observed drastic increase in the hyperfine quadrupole splitting (QS) between 13 and 32 GPa can be associated with an enhanced local distortion of the A-site Fe2+ in Bm6. In contrast to Bm6, the enhanced lattice distortion and the presence of extremely high QS values of Fe2+ are not observed in Al-Bm11 at high pressures. Our results here support the notion that the occurrence of the extremely high QS component of approximately 4 mm/s in bridgmanite is due to the lattice distortion in the high-spin (HS) A-site Fe2+, instead of the occurrence of the intermediate-spin state. Both A-site Fe2+ and Fe3+ in Bm6 and Al-Bm11 remain in the HS state at lower-mantle pressures. Together with XRD results, we present the first experimental evidence that the enhanced lattice distortion of A-site Fe2+ does not cause any detectable variation in the EoS parameters, but is associated with anomalous variations in the bond length, tilting angle, and shear strain in the octahedra of Bm6. Analysis of the obtained EoS parameters of bridgmanite at lower-mantle pressures indicates that the substitution of Fe in bridgmanite will cause an enhanced density and a reduced bulk sound velocity (VΦ), whereas the Al and Fe substitution has a reduced effect on density and a negligible effect on VΦ. These experimental results provide new insight into the correlation between lattice, hyperfine, and EoS parameters of bridgmanite in the Earth's lower mantle.

AB - In this study, we performed synchrotron X-ray diffraction (XRD) and Mössbauer spectroscopy (SMS) measurements on two single-crystal bridgmanite samples [Mg0.94 Fe0.04 2+Fe0.02 3+ Al0.01Si0.99O3 (Bm6) and Mg0.89 Fe0.024 2+Fe0.096 3+ Al0.11Si0.89O3 (Al-Bm11)] to investigate the combined effect of Fe and Al on the hyperfine parameters, lattice parameters, and equation of state (EoS) of bridgmanite up to 130 GPa. Our SMS results show that Fe2+ and Fe3+ in Bm6 and Al-Bm11 are predominantly located in the large pseudo-dodecahedral sites (A-site) at lower-mantle pressures. The observed drastic increase in the hyperfine quadrupole splitting (QS) between 13 and 32 GPa can be associated with an enhanced local distortion of the A-site Fe2+ in Bm6. In contrast to Bm6, the enhanced lattice distortion and the presence of extremely high QS values of Fe2+ are not observed in Al-Bm11 at high pressures. Our results here support the notion that the occurrence of the extremely high QS component of approximately 4 mm/s in bridgmanite is due to the lattice distortion in the high-spin (HS) A-site Fe2+, instead of the occurrence of the intermediate-spin state. Both A-site Fe2+ and Fe3+ in Bm6 and Al-Bm11 remain in the HS state at lower-mantle pressures. Together with XRD results, we present the first experimental evidence that the enhanced lattice distortion of A-site Fe2+ does not cause any detectable variation in the EoS parameters, but is associated with anomalous variations in the bond length, tilting angle, and shear strain in the octahedra of Bm6. Analysis of the obtained EoS parameters of bridgmanite at lower-mantle pressures indicates that the substitution of Fe in bridgmanite will cause an enhanced density and a reduced bulk sound velocity (VΦ), whereas the Al and Fe substitution has a reduced effect on density and a negligible effect on VΦ. These experimental results provide new insight into the correlation between lattice, hyperfine, and EoS parameters of bridgmanite in the Earth's lower mantle.

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