Crystal structure, equation of state and elasticity of phase H
Pressure dependence of unit-cell volume and lattice parameters. The left panel shows the plot of unit-cell volume as a function of pressure for phase H with ordered Mg and Si atoms (model-1 ...
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FeO2 and FeOOH under deep lower-mantle conditions and Earth
Using a Nd-doped Y 3 Al 5 O 12 laser system 7 to heat the sample to 1,800 K in situ at high pressure, the sample became semi-transparent, suggesting that a chemical reaction had occurred.
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High-Pressure Evolution of Crystal Bonding …
Our results indicate a phase transition around 70 GPa from the known ε-FeOOH to a new pyrite-type FeOOH (P-FeOOH) phase, and the two phases remain …
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High-pressure Raman spectroscopic studies of FeS2 pyrite
Abstract We report micro-Raman spectroscopic studies of FeS2 pyrite in the diamond-anvil cell under hydrostatic and non-hydrostatic conditions to 55 GPa at room temperature. Four out of five Raman-active modes are resolved with helium as a pressure-transmitting medium to highest pressures. The fifth mode, Tg(2) [377 cm-1], is weak and …
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Isotopic Compositions of Sulfides in Exhumed High‐Pressure …
Thus, pyrite breakdown to pyrrhotite reactions operating during subduction metamorphism should produce oxidized Fe-depleted peak mineral assemblages in exhumed high-pressure rocks. Additionally, the low solubility of reduced sulfur species in rock-buffered systems suggests that sulfides may continue to persist in the slab (Evans …
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(PDF) High-pressure Raman spectroscopic studies of FeS 2 pyrite
, pyrite, Raman spectroscopy, high pressure, diamond-anvil cell. In t ro du c tio n. T. HE transition metal dichalcogenide FeS. 2, pyrite, is the most abundant of the sulphide minerals and. common ...
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The Pyrite-Type High-Pressure Form of Silica
The Pyrite-Type High-Pressure Form of Silica. sets of parameters. Keeping w± fixed, the L/d are chosen (Fig. 2A) so that all the lines intersect the data point for the …
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Reaction mechanism of metal and pyrite under high-pressure and high
The changing trends in the lattice energy of the same substance under a high pressure are the same as that of 1/R 0. Under a high pressure, the distance between ions in pyrite decreases due to compression, and the lattice energy increases accordingly. The lattice energy of pyrite shows the most obvious increase between 0–3 GPa (Fig. 3(a ...
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The pyrite-type high-pressure form of FeOOH
The pyrite-type high-pressure form of FeOOH. This work reports the formation of a new FeOOH phase with the pyrite-type framework of FeO6 octahedra, which is much denser than the surrounding mantle and is stable at the conditions of the base of the mantle. Expand.
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The Pyrite-Type High-Pressure Form of Silica | Semantic …
X-ray diffraction measurements showed that a high-pressure form with a pyrite-type structure, denser than other known silica phases, is stable above 268 giga-pascals and 1800 kelvin. The silicon coordination number increases from 6 in the α-PbO2-type phase to 6+2 in the pyrite-type phase, leading to a large increase in density by …
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Acoustic velocities and elastic properties of pyrite (FeS
Ultrasonic interferometry was utilized in conjunction with synchrotron-based X-ray diffraction and X-radiographic imaging to determine the compressional and shear wave velocities and unit-cell volumes of pyrite (FeS2) at room temperature and pressures up to 9.6 GPa. Fitting all of the experimental volume and velocity data to third-order finite …
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In situ high-temperature phase transformation studies on pyrite
In this paper, we report an in situ high-temperature X-ray diffraction study of phase transformations in pyrite under variable environmental conditions (atmospheric pressure (1 atm.), low air pressure (<0.001 atm.), inert and carbon dioxide atmosphere). We observe that while heating of pyrite in air promotes the formation of hematite (α-Fe 2 …
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Raman Spectroscopic Studies of Pyrite at High Pressure …
3.2. Simultaneous High-Temperature and High-Pressure Study of Pyrite Water reacts with pyrite as a function of temperature, pressure, and time. To avoid the reaction between water and pyrite, methanol–ethanol (4:1) was used as a pressure medium instead of a 20 wt.% NaCl solution [16] to provide hydrostatic pressure.
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In Situ Electrochemical Investigation of Acidic Pressure …
pressure oxidation process, gold bearing pyrite is subjected to high-temperature, high-pressure oxidation in autoclaves to destroy pyrite lattice.12,13 This process has been practiced commercially since the early1980s,14 and is widely accepted by the gold mining industry all over the world for its high efficiency and low pollution.
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High-Pressure Synthesis of High-Entropy Metal Disulfides with Pyrite
To test the stability of high-pressure phases, we annealed the samples at ambient pressure with flowing nitrogen gas. A pyrite single phase of (Fe, Co, Ni, Cu)S 2 decomposed into pyrite-type phases and the NiAs-type phase after annealing at 400 °C. The phase of the sample prepared at high pressure was not stable at ambient pressure …
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Pressure-induced structural transition and metallization …
The high-pressure behavior of manganese diselenide MnSe2 was investigated by synchrotron angle-dispersive X-ray diffraction (ADXRD) and infrared reflection spectroscopy equipped with a diamond-anvil cell. It was found that MnSe2 with a pyrite-type structure undergoes a transformation into a disordered intermediate phase at …
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The Pyrite-Type High-Pressure Form of Silica | Science
Abstract. Silica (SiO 2) exhibits extensive polymorphism at elevated pressures. X-ray diffraction measurements showed that a high-pressure form with a pyrite-type structure, denser than other known silica phases, is stable above 268 giga-pascals and 1800 kelvin. The silicon coordination number increases from 6 in the α-PbO …
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Redox processes in subducting oceanic crust recorded by …
Large pyrite grains in the matrix contain inclusions of garnet, omphacite and other HP index minerals. However, magnetite replacing pyrite textures are commonly observed in the retrograded samples. ... Berry RF, Green DH (1991) High pressure experimental calibration of the olivine-orthopyroxene-spinel oxygen geobarometer: …
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The pyrite-type high-pressure form of FeOOH | Nature
The pyrite-type high-pressure form of FeOOH. Masayuki Nishi, Yasuhiro Kuwayama, Jun Tsuchiya & Taku Tsuchiya. Nature 547, 205–208 ( 2017) Cite this article. 16k Accesses. 121 Citations....
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Behavioral response of pyrite structured Co0.2Fe0.8S2 nano …
Pyrite-structured Co 0.2 Fe 0.8 S 2 nano wires with aspect ratio 45:1, synthesized using solution colloid method were studied under high pressure up to 8 GPa using 57 Fe Möss spectroscopy (using diamond anvil cell) and electrical resistivity (using tungsten carbide cell) techniques. Room temperature S K-edge XANES studies at …
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Pressure induced phase transition in MnTe2 studied by …
The resulting high pressure phase is notably also cubic, and most probably of the pyrite type. Compared with other transitions between isostructural phases, the AV/V=0.16 volume change is strikingly large. Representative examples of the observed EDS patterns for the low- and high-pressure pyrite type modifications of MnTe2 are …
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Pyrite form of group-14 element pernitrides synthesized at high
The chemical reaction of group-14 elements with molecular nitrogen at pressures above 60 GPa successfully leads to the formation of pyrite-type pernitrides. These new crystalline group-14 elemental pernitrides were found to show a bulk modulus higher than the other known group-14 elemental nitrides. Our resu
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The pyrite-type high-pressure form of FeOOH
Pyrite-type FeOOH may stabilize as a solid solution with other hydrous minerals in deeply subducted slabs, and could form in subducted banded iron formations. Deep-seated pyrite-type FeOOH eventually dissociates into Fe 2 O 3 and releases H 2 O when subducted slabs are heated at the base of the mantle. This process may cause the …
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Elastic Properties of the Pyrite‐Type FeOOH‐AlOOH System …
An analogous, high-pressure phase transition from CaCl 2-type ϵ-FeOOH (Figure 1a) to pyrite-type FeO 2 H (Figure 1b) was discovered by high-pressure experimentalists in the past few years, but the stoichiometry and properties of this phase remain contested (Hu et al., 2016, 2017; Liu et al., 2017; Nishi et al., 2017; L. Yuan et al., …
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First-principles thermoelasticity and stability of pyrite-type …
The pyrite-type FeO 2 was proposed recently as a new structure that exists in the deep Earth. Taking into account the influence of temperature, we investigated the stability and elastic properties of pyrite-type FeO 2 under high pressure. The obtained lattice constants and bulk modulus agree well with the available experimental and …
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Pyrite form of group-14 element pernitrides synthesized at high …
The chemical reaction of group-14 elements with molecular nitrogen at pressures above 60 GPa successfully leads to the formation of pyrite-type pernitrides, which offer significant new progress in the solid-state chemistry of nitrides. The chemical reaction of group-14 elements with molecular nitrogen at pressures above 60 GPa …
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The Pyrite-Type High-Pressure Form of Silica
The Pyrite-Type High-Pressure Form of Silica. Y. Kuwayama, K. Hirose, +1 author. Y. Ohishi. Published in Science 5 August 2005. Materials Science. TLDR. X-ray …
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The pyrite-type high-pressure form of silica
X-ray diffraction measurements showed that a high-pressure form with a pyrite-type structure, denser than other known silica phases, is stable above 268 giga-pascals and 1800 kelvin. The silicon coordination number increases from 6 in the alpha-PbO2-type phase to 6+2 in the pyrite-type phase, leading to a large increase in density …
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Transition metal pyrite dichalcogenides. High-pressure …
DOI: 10.1021/IC50069A008 Corpus ID: 95559793; Transition metal pyrite dichalcogenides. High-pressure synthesis and correlation of properties @article{Bither1968TransitionMP, title={Transition metal pyrite dichalcogenides.
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The Pyrite-Type High-Pressure Form of Silica | Science
X-ray diffraction measurements showed that a high-pressure form with a pyrite-type structure, denser than other known silica phases, …
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