Probing carbon-bearing species and CO2inclusions in amorphous carbon-MgSiO3enstatite reaction products at 1.5 GPa: Insights from13C high-resolution solid-state NMR

Kim, Eun Jeong; Fei, Yingwei; Lee, Sung Keun

doi:10.2138/am-2016-5563

Cited by 7 publications

(3 citation statements)

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“…A similar method of background subtraction has been applied to yield a quantitative (artifactfree) NMR signal from a relatively small amount of samples (such as carbon species in fluid inclusion and Al-species in oxide thin films). 28,29 Powder X-ray diffraction of the sample was performed at the 16IDB beamline at the Advanced Photon Source (APS) using a microfocused (∼10 × 10 μm) monochromatic synchrotron Xray (λ = 0.3682 Å) and a 2D X-ray detector (1M, PILATUS). The X-ray work was only performed above 30 GPa, where CO samples become stable under X-ray or laser illumination.…”

Section: ■ Methodsmentioning

confidence: 99%

“…The background spectrum was subsequently subtracted from the 13 C MAS NMR spectrum for each sample to yield the NMR spectrum free from any background carbon signals. A similar method of background subtraction has been applied to yield a quantitative (artifact-free) NMR signal from a relatively small amount of samples (such as carbon species in fluid inclusion and Al-species in oxide thin films). , …”

Section: Methodsmentioning

confidence: 99%

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Hydrogen-Doped Polymeric Carbon Monoxide at High Pressure

et al. 2017

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The ability to control materials stability, bonding, and transformation by thermo-mechanical and chemical means is significant for development of high-energy-density extended solids. We report that doping hydrogen (∼10%) in carbon monoxide (CO) can greatly lower the polymerization pressure of CO and enhance the stability of recovered polymeric CO products at ambient conditions. Hydrogen-doped CO crystallizes into well-grown dendrites of β-CO-like phase at 3.2 GPa, which polymerizes to highly unsaturated black polymer (phase I) at ∼4.7 (5.8) GPa. Upon further compression, this highly colored polymer transforms into a translucent 3D network structure (phase II) at 6–7 (10–17) GPa and then a transparent 2D layer structure (phase III) at 20–30 (30–60) GPa. A similar series of transformations are also found in pure CO but at considerably higher transition pressures, as noted in parentheses. All polymeric phases are recoverable at ambient conditions, exhibiting an array of phase stability and novel properties such as chemically unstable phase I, highly luminescent phase II, and highly transparent layered phase III. The density of recovered products ranges from ∼2.3 g/cm3 to 3.6 g/cm3, depending on the pressure recovered. The recovered products are highly disordered but slowly decompose to crystalline solids of anhydrous polymeric oxalic acid while exhibiting interesting crystal morphologies such as nm-cobs, nm-lamellar layers, and μm-bales. The present first-principles MD simulations suggest that the polymerization occurs at 6 (or 10) GPa in H2-doped (or pure) CO. While not directly participating in the reaction, the role of H2 molecules is to enhance the mobility of CO molecules leading to the polymerization.

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Section: ■ Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Hydrogen-Doped Polymeric Carbon Monoxide at High Pressure

et al. 2017

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“…During curve-fitting, it was kept in mind that the source of carbon was a mixture of 13 C and C, which would lead to a doublet of peaks for each vibration (Kim et al, 2016).…”

Section: Resultsmentioning

confidence: 99%

Experimental, in-situ carbon solution mechanisms and isotope fractionation in and between (C–O–H)-saturated silicate melt and silicate-saturated (C–O–H) fluid to upper mantle temperatures and pressures

Mysen

2017

Earth and Planetary Science Letters

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Our understanding of materials transport processes in the Earth relies on characterizing the behavior of fluid and melt in silicate-(C-O-H) systems at high temperature and pressure. Here, Raman spectroscopy was employed to determine structure of and carbon isotope partitioning between melts and fluids in alkali aluminosilicate-CO -H systems. The experimental data were recorded in-situ while the samples were at equilibrium in a hydrothermal diamond anvil cell at temperatures and pressures to 825˚C and >1300 MPa, respectively. The carbon solution equilibrium in both (C-O-H)-saturated melt and coexisting, silicate-saturated (C-O-H) fluid is 2CO 3 +H 2 O+2Q n+1 =2HCO 3 +2Q n. In the Q n-notation, the superscript, n, is the number of bridging oxygen in silicate structural units. At least one oxygen in CO 3 and HCO 3 groups likely is shared with silicate tetrahedra. The structural behavior of volatile components described with this equilibrium governs carbon isotope fractionation factors between melt and fluid. For example, the ∆H equals 3.2±0.7 kJ/mol for the bulk 13 C/ 12 C exchange equilibrium between fluid and melt. From these experimental data, it is suggested that at deep crustal and upper mantle temperatures and pressures, the 13 C-differences between coexisting silicate-saturated (C-O-H) fluid and (C-O-H)-saturated silicate melts may change by more than 100 ‰ as a function of temperature in the range of magmatic processes. Absent information on temperature and pressure, the use of carbon isotopes of mantle-derived magma to derive isotopic composition of magma source regions in the Earth's interior, therefore, should be exercised with care.

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