High-temperature compression experiments of CaSiO3 perovskite to lowermost mantle conditions and its thermal equation of state

Noguchi, M.; Komabayashi, Tetsuya; Hirose, Kei; Ohishi, Yasuo

doi:10.1007/s00269-012-0549-1

Cited by 24 publications

(56 citation statements)

References 39 publications

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“…The key result here is that at the temperatures and pressures found in the lower part of the lower mantle, the cubic structure of CaSiO 3 is always more stable, and in fact becomes more stable the deeper into the mantle one goes, from 0.075 meV -at 100 GPa -to 0.122 meV -at 135 GPa -lower in free energy than the lowest energy distorted structure (at the lowest temperature considered for each pressure). This supports previous work that suggests that calcium silicate is cubic in the lower mantle 15,26,28,30,31 , utilising a novel high accuracy firstprinciples method to complement previous work. The distortion that is lowest in free energy changes as the pressure and temperature increase, going from C2/m at 100 GPa to I4/mcm at an estimated crossover pressure of 117 GPa.…”

Section: Relative Stabilitiessupporting

confidence: 88%

“…Previous experimental work by Noguchi et al 31 has provided several different models for a thermal equation of state for cubic calcium silicate perovskite under lower mantle conditions. Using these models allows us to link pressure, volume and temperature, and find an estimate for the volume at a given pressure and temperature, including the effects of thermal expansion.…”

Section: E Thermal Expansionmentioning

confidence: 99%

“…Here, we use the thermodynamic thermal pressure model (model 4 in Ref. 31), which gives the equation of state as…”

Section: E Thermal Expansionmentioning

confidence: 99%

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First-principles anharmonic vibrational study of the structure of calcium silicate perovskite under lower mantle conditions

Prentice

Needs

2019

Phys. Rev. B

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Calcium silicate perovskite (CaSiO3) is one of the major mineral components of the lower mantle, but has been the subject of relatively little work compared to the more abundant Mg-based materials. One of the major problems related to CaSiO3 that is still the subject of research is its crystal structure under lower mantle conditions -a cubic Pm3m structure is accepted in general, but some have suggested that lower-symmetry structures may be relevant. In this work, we use a fully firstprinciples vibrational self-consistent field (VSCF) method to perform high accuracy anharmonic vibrational calculations on several candidate structures at a variety of points along the geotherm near the base of the lower mantle, in order to investigate the stability of the cubic structure and related distorted structures. Our results show that the cubic structure is the most stable throughout the lower mantle, and that this result is robust against the effects of thermal expansion.

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Section: Relative Stabilitiessupporting

confidence: 88%

Section: E Thermal Expansionmentioning

confidence: 99%

See 1 more Smart Citation

First-principles anharmonic vibrational study of the structure of calcium silicate perovskite under lower mantle conditions

Prentice

Needs

2019

Phys. Rev. B

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“…Continuously improved values emerge both from experiments [e.g., Murakami et al, 2012] and from first principle calculations [e.g., Wu et al, 2013]. Results include the effects of major element composition [e.g., Kudo et al, 2012;Noguchi et al, 2013], effects of the presence of volatiles [e.g., Inoue et al, 2010;Hern andez et al, 2013], and the behavior of the spin transition in iron-bearing components [e.g., Lin et al, 2007;Antonangeli et al, 2011;Mao et al, 2011;Nomura et al, 2011;Wu et al, 2013]. In this study, we demonstrate that part of this divergence in the interpretation is due to past studies adopting an inconsistent and incorrect methodology and from basing results on either bulk sound or shear wave velocity alone.…”

Section: Introductionmentioning

confidence: 99%

BurnMan: A lower mantle mineral physics toolkit

Cottaar

Heister

Rose

et al. 2014

Geochem. Geophys. Geosyst.

104

100

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We present BurnMan, an open-source mineral physics toolbox to determine elastic properties for specified compositions in the lower mantle by solving an Equation of State (EoS). The toolbox, written in Python, can be used to evaluate seismic velocities of new mineral physics data or geodynamic models, and as the forward model in inversions for mantle composition. The user can define the composition from a list of minerals provided for the lower mantle or easily include their own. BurnMan provides choices in methodology, both for the EoS and for the multiphase averaging scheme. The results can be visually or quantitatively compared to observed seismic models. Example user scripts show how to go through these steps. This paper includes several examples realized with BurnMan: First, we benchmark the computations to check for correctness. Second, we exemplify two pitfalls in EoS modeling: using a different EoS than the one used to derive the mineral physical parameters or using an incorrect averaging scheme. Both pitfalls have led to incorrect conclusions on lower mantle composition and temperature in the literature. We further illustrate that fitting elastic velocities separately or jointly leads to different Mg/Si ratios for the lower mantle. However, we find that, within mineral physical uncertainties, a pyrolitic composition can match PREM very well. Finally, we find that uncertainties on specific input parameters result in a considerable amount of variation in both magnitude and gradient of the seismic velocities.

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“…(4) Wang et al (1996) CaSiO 3 Cubic 236(4) 3.9(2) Shim et al (2000) CaSiO 3 Tetragonal 255(5) 4(fixed) Shim et al (2002) CaSiO 3 Cubic 207(4) 4.0(fixed) Noguchi et al (2013) Therefore, the unit-cell volume may shrink in certain direction and expand in other directions, and finally the whole structure shows a negative temperature dependence coefficient. Further studies are required to investigate the mechanism of the negative temperature dependence coefficient.…”

Section: P-v-t Relations Of Low-pressure Ca 2 Alsio 55 Oxygen Defectmentioning

confidence: 97%

Equation of state of Ca2AlSiO5.5 oxygen defect perovskite

Zhai

et al. 2014

Phys Chem Minerals

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High-temperature compression experiments of CaSiO3 perovskite to lowermost mantle conditions and its thermal equation of state

Cited by 24 publications

References 39 publications

First-principles anharmonic vibrational study of the structure of calcium silicate perovskite under lower mantle conditions

First-principles anharmonic vibrational study of the structure of calcium silicate perovskite under lower mantle conditions

BurnMan: A lower mantle mineral physics toolkit

Equation of state of Ca2AlSiO5.5 oxygen defect perovskite

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