Pressure-induced structural evolution of pyrite-type SiO2

Kuwayama, Yasuhiro; Hirose, Kei; Sata, Nagayoshi; Ohishi, Yasuo

doi:10.1007/s00269-011-0431-6

Cited by 21 publications

(21 citation statements)

References 36 publications

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“…The starting material and thermal insulator were formed into thin disks each of ∼15 μ m thickness, and put into the sample chamber. Detail of the similar experimental techniques can be seen in Sinmyo et al [2008] and Kuwayama et al [2011]. Similar to the SDMA experiments, samples were compressed first to the target pressures, after which MgSiO 3 perovskite and MgO were synthesized by decomposition of Mg 2 SiO 4 olivine at high temperatures.…”

Section: Methodsmentioning

confidence: 99%

P‐V‐T equation of state of MgSiO₃ perovskite based on the MgO pressure scale: A comprehensive reference for mineralogy of the lower mantle

et al. 2012

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In situ P‐V‐T measurements of MgSiO3 perovskite were carried out up to 110 GPa and 2500 K, using a sintered‐diamond multianvil apparatus and a laser‐heated diamond anvil cell together with synchrotron radiation. The P‐V‐T data sets obtained by multianvil experiments (28–63 GPa and 300–1500 K) and diamond anvil cell experiments (52–108 GPa and 300, 1500–2430 K) are consistent with each other. The equation of state of MgSiO3 perovskite was subsequently represented by a Mie‐Grüneisen‐Debye model, using the equation of state of MgO as reference for pressure determination. In this study, we provide mutually consistent and precise P‐V‐T equations of state of MgSiO3 perovskite and MgO applicable to the bottom of the Earth's lower mantle. These P‐V‐T equations of state and derivative thermodynamic and elastic properties are essential for mineralogy of the lower mantle as a comprehensive reference.

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Section: Methodsmentioning

confidence: 99%

P‐V‐T equation of state of MgSiO₃ perovskite based on the MgO pressure scale: A comprehensive reference for mineralogy of the lower mantle

et al. 2012

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“…The bulk modulus of the amorphous phases at high pressures approaches that of the counterpart crystalline structure [K 0 = 304 (8) GPa for a-GeO 2 compared to K 0 = 347 (12) GPa for the pyrite structure which has a sixfold coordinated structure] indicating that the compressibility is almost the same between the two compounds. Indeed, at such high pressure the compaction of the structure is dominated by bond shortening, or rotation of the octahedron [49,50], and coordination change is less likely.…”

Section: Results and Comparison With Previous Reportsmentioning

confidence: 99%

Density of amorphous GeO2 to 133 GPa with possible pyritelike structure and stiffness at high pressure

et al. 2019

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Germanium oxide is a prototype network-forming oxide with pressure-induced structural changes similar to those found in crystals and amorphous silicate oxides at high pressure. Studying density and coordination changes in amorphous GeO 2 allows for insight into structural changes in silicate oxides at very high pressure, with implications for the properties of planetary magmas. Here, we report the density of germanium oxide glass up to 133 GPa using the x-ray absorption technique, with very good agreement with previous experimental data at pressure below 40 GPa and recent calculation up to 140 GPa. Our data highlight four distinct compressibility domains, corresponding to changes of the local structure of GeO 2. Above 80 GPa, our density data show a compressibility and bulk modulus similar to the counterpart crystal phase, and we propose that a compact distorted sixfold coordination, similar to the structural motif of the pyritelike crystalline GeO 2 polymorph, is likely to be stable in that pressure range. Our density data point to a smooth continuous evolution of the average coordination for pressure above 20 GPa with persistent sixfold coordination, without sharp density or density slope discontinuities. These observations are in very good agreement with theoretical calculations and spectroscopic measurements, and our results indicate that glasses and melts may behave similarly to their high-pressure solid counterparts with comparable densities, compressibility, and possibly average coordination.

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“…where q is the volume dependence on the Grüneisen parameter. By fitting five parameters (V 0 , K 0 , K 0 , γ 0 and q) with the Debye temperature θ 0 = 314 K [21], the following parameters were determined for NM- [27]. Black solid diamond symbols show the volume at high pressure and 300 K. Solid and dashed lines in (a,c) show the compression curves from this study and the study of Sata et al [20], respectively.…”

Section: Compression Behavior and The Thermal Equation Of State Of Fementioning

confidence: 94%

“…The experimental pressures were determined using the EOS of KBr (B2) [22] and that of MgO [23] for the high-pressure and high-temperature experiments, whereas the compression curve of pyrite SiO 2 at 300 K was used for determination of pressure for the experiments exceeding 298.9 GPa [27]. The temperature distribution in the pressure medium in the double-heated diamond anvil cell (DAC) was evaluated from 3-dimensional numerical modeling [28].…”

Section: In Situ Xrd Experiments At the Bl10xu Beamline At Spring-8mentioning

confidence: 99%

“…The compression behavior of Fe 3 C above 298.9 GPa at 300 K was obtained after quenching the sample from high temperatures above 1500 K, releasing stress during solid state compression. Its experimental pressures were determined by the equation of state of pyrite-type SiO 2 [27]. Previous studies show that the magnetic transition of Fe 3 C to a nonmagnetic phase occurs at 20-25 GPa [13,19].…”

Section: X-ray Diffraction Patterns Of Fe 3 Cmentioning

confidence: 99%

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Thermal Equation of State of Fe3C to 327 GPa and Carbon in the Core

et al. 2019

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The density and sound velocity structure of the Earth's interior is modeled on seismological observations and is known as the preliminary reference Earth model (PREM). The density of the core is lower than that of pure Fe, which suggests that the Earth's core contains light elements. Carbon is one plausible light element that may exist in the core. We determined the equation of state (EOS) of Fe 3 C based on in situ high-pressure and high-temperature X-ray diffraction experiments using a diamond anvil cell. We obtained the P-V data of Fe 3 C up to 327 GPa at 300 K and 70-180 GPa up to around 2300 K. The EOS of nonmagnetic (NM) Fe 3 C was expressed by two models using two different pressure scales and the third-order Birch-Murnaghan EOS at 300 K with the Mie-Grüneisen-Debye EOS under high-temperature conditions. The EOS can be expressed with parameters of V 0 = 148.8(±1.0) Å 3 , K 0 = 311.1(±17.1) GPa, K 0 = 3.40(±0.1), γ 0 = 1.06(±0.42), and q = 1.92(±1.73), with a fixed value of θ 0 = 314 K using the KBr pressure scale (Model 1), and V 0 = 147.3(±1.0) Å 3 , K 0 = 323.0(±16.6) GPa, K 0 = 3.43(±0.09), γ 0 = 1.37(±0.33), and q = 0.98(±1.01), with a fixed value of θ 0 = 314 K using the MgO pressure scale (Model 2). The density of Fe 3 C under inner core conditions (assuming P = 329 GPa and T = 5000 K) calculated from the EOS is compatible with the PREM inner core.

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Pressure-induced structural evolution of pyrite-type SiO2

Cited by 21 publications

References 36 publications

P‐V‐T equation of state of MgSiO₃ perovskite based on the MgO pressure scale: A comprehensive reference for mineralogy of the lower mantle

P‐V‐T equation of state of MgSiO₃ perovskite based on the MgO pressure scale: A comprehensive reference for mineralogy of the lower mantle

Density of amorphous GeO2 to 133 GPa with possible pyritelike structure and stiffness at high pressure

Thermal Equation of State of Fe3C to 327 GPa and Carbon in the Core

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Pressure-induced structural evolution of pyrite-type SiO2

Cited by 21 publications

References 36 publications

P‐V‐T equation of state of MgSiO3 perovskite based on the MgO pressure scale: A comprehensive reference for mineralogy of the lower mantle

P‐V‐T equation of state of MgSiO3 perovskite based on the MgO pressure scale: A comprehensive reference for mineralogy of the lower mantle

Density of amorphous GeO2 to 133 GPa with possible pyritelike structure and stiffness at high pressure

Thermal Equation of State of Fe3C to 327 GPa and Carbon in the Core

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P‐V‐T equation of state of MgSiO₃ perovskite based on the MgO pressure scale: A comprehensive reference for mineralogy of the lower mantle

P‐V‐T equation of state of MgSiO₃ perovskite based on the MgO pressure scale: A comprehensive reference for mineralogy of the lower mantle