Equation of state of ice VII up to 106 GPa

Wolanin, E.; Pruzan, Ph.; Chervin, J. C.; Canny, B.; Gauthier, Michel; Häusermann, Daniel M.; Hanfland, Michael

doi:10.1103/physrevb.56.5781

Cited by 118 publications

(122 citation statements)

References 29 publications

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“…One or two pieces of ruby and a gold chip (when applicable) were placed around the sample to calibrate the pressure. At high pressure where ruby fluorescence becomes weak, pressure is calibrated by the EOS of Ne (24), Ar (25), Au (26), or ice (27). Details regarding the pressure calibration are listed in Table S7.…”

Section: Methodsmentioning

confidence: 99%

Dehydrogenation of goethite in Earth’s deep lower mantle

Kim

Liu

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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The cycling of hydrogen influences the structure, composition, and stratification of Earth's interior. Our recent discovery of pyrite-structured iron peroxide (designated as the P phase) and the formation of the P phase from dehydrogenation of goethite FeO 2 H implies the separation of the oxygen and hydrogen cycles in the deep lower mantle beneath 1,800 km. Here we further characterize the residual hydrogen, x, in the P-phase FeO 2 Hx. Using a combination of theoretical simulations and high-pressure-temperature experiments, we calibrated the x dependence of molar volume of the P phase. Within the current range of experimental conditions, we observed a compositional range of P phase of 0.39 < x < 0.81, corresponding to 19-61% dehydrogenation. Increasing temperature and heating time will help release hydrogen and lower x, suggesting that dehydrogenation could be approaching completion at the high-temperature conditions of the lower mantle over extended geological time. Our observations indicate a fundamental change in the mode of hydrogen release from dehydration in the upper mantle to dehydrogenation in the deep lower mantle, thus differentiating the deep hydrogen and hydrous cycles.

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Section: Methodsmentioning

confidence: 99%

Dehydrogenation of goethite in Earth’s deep lower mantle

Kim

Liu

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…2). It is worth noticing that clathrate B is stiffer than both ice VI and ice VII, the bulk modulus values of which are 17.8 and 27.8 GPa, respectively (18,19); this probably results from the very tight packing of xenon inside the H 2 O network of clathrate B.…”

mentioning

confidence: 99%

High-pressure transformations in xenon hydrates

Sanloup

Mao

Hemley

2001

Proc. Natl. Acad. Sci. U.S.A.

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A high-pressure investigation of the Xe⅐H2O chemical system was conducted by using diamond-anvil cell techniques combined with in situ Raman spectroscopy, synchrotron x-ray diffraction, and laser heating. Structure I xenon clathrate was observed to be stable up to 1.8 GPa, at which pressure it transforms to a new Xe clathrate phase stable up to 2.5 GPa before breaking down to ice VII plus solid xenon. The bulk modulus and structure of both phases were determined: 9 ؎ 1 GPa for Xe clathrate A with structure I (cubic, a ‫؍‬ 11.595 ؎ 0.003 Å, V ‫؍‬ 1,558.9 ؎ 1.2 Å 3 at 1.1 GPa) and 45 ؎ 5 GPa for Xe clathrate B (tetragonal, a ‫؍‬ 8.320 ؎ 0.004 Å, c ‫؍‬ 10.287 ؎ 0.007 Å, V ‫؍‬ 712.1 ؎ 1.2 Å 3 at 2.2 GPa). The extended pressure stability field of Xe clathrate structure I (A) and the discovery of a second Xe clathrate (B) above 1.8 GPa have implications for xenon in terrestrial and planetary interiors.

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“…Nonetheless, we find that our results yields an equation of state and lattice cell parameter within ca. 10% of experimental results [8,10]. …”

Section: Resultsmentioning

confidence: 99%

“…Comparison of the total x-ray scattering intensity of ice VII to the symmetrically hydrogen bonded form of superionic water. It was difficult to make a direct comparison of our spectrum of ice VII (95 GPa and 300 K) to experiment due to the fact that only a few studies exist at the same conditions [8,10,12], and none publish detailed spectral features at ca. P = 100 GPa.…”

Section: Resultsmentioning

confidence: 99%

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X-ray scattering intensities of water at extreme pressure and temperature

Goldman

Fried

2007

The Journal of Chemical Physics

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We have calculated the coherent x-ray scattering intensity of several phases of water at 1500 and 2000 K under high pressure, using ab initio Density Functional Theory (DFT). Our calculations span the molecular liquid, ice VII, and superionic solid phases, including the recently predicted symmetrically hydrogen bonded region of the superionic phase. We show that wide angle x-ray scattering intensity could be used to determine phase boundaries between these high pressure phases, and we compare the results for ice VII and superionic water. We compute simulated spectra and provide new atomic scattering form factors for water at extreme conditions, which take into account frequently neglected changes in ionic charge and electron delocalization. We show that our modifed atomic form factors allow for a nearly exact comaprison to the total x-ray scattering intensities calculated from DFT. Finally, we analyze the effect our new form factors have on determination of the oxygen-oxygen radial distribution function.

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Equation of state of ice VII up to 106 GPa

Cited by 118 publications

References 29 publications

Dehydrogenation of goethite in Earth’s deep lower mantle

Dehydrogenation of goethite in Earth’s deep lower mantle

High-pressure transformations in xenon hydrates

X-ray scattering intensities of water at extreme pressure and temperature

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