Neutron study of dynamics of solid hydrogen under pressure

Ishmaev, S.N.; Kobelev, G. V.; Sadikov, I. P.; Sukhoparov, V. A.; Чернышов, А. А.; Telepnev, A. S.; Vindryaevskiǐ, B. A.; Shitikov, Yu. L.

doi:10.1016/s0921-4526(96)00867-8

Cited by 15 publications

(22 citation statements)

References 3 publications

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“…25 in comparison with density-functional theory (DFT)-generalized gradient approximation (GGA) calculations [26] and the main experimental results from [3,5,[7][8][9][10]12,13,16]. It was shown that the semi-empirical (SE) calculations with the proposed many-body potential are in an excellent agreement with experiment in the pres-sure range 1-140 GPa (phases I and II).…”

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confidence: 85%

“…The central characteristics of every substance is equation of state (EOS) which is a basis for studying all physical properties of the substance, in particular for developing and examining model intermolecular potentials and testing ab initio theories. Systematic high-pressure studies of the EOS of solid hydrogens were started in the 1970s [1][2][3][4][5][6], and at present they reach the pressures up to ~2 Mbar [7][8][9][10][11][12][13]. The highest volume compression reached in the EOS experiments is 10.4 for solid hydrogen [13] (7.6 for solid D 2 [12]), higher than for solid helium (8.4) [14].…”

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confidence: 99%

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Sound velocities in solid hydrogen under pressure

Freǐman

Grechnev

Tretyak

et al. 2013

Low Temperature Physics

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We present results of semi-empirical lattice dynamics calculations of the sound velocities in solid hydrogen under pressure based on the many-body intermolecular potential and first-principle density-functional theory (DFT). Both the sound velocities and elastic moduli are in excellent agreement with data from Brillouin scattering measurements while Silvera-Goldman and Hemley-Silvera-Goldman potentials tend to overestimate the sound velocity. It is shown that the stiffer is the potential the greater is overestimated the sound velocity. As was the case for equation of state and Raman-active lattice phonon calculations, the employed many-body potential works well for phases I and II (up to ~ 140 GPa while for higher pressures the use of the DFT is preferable.

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confidence: 85%

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Sound velocities in solid hydrogen under pressure

Freǐman

Grechnev

Tretyak

et al. 2013

Low Temperature Physics

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“…The deuterium clathrates synthesized have sII structure (space group Fd3m), and all of the patterns were analyzed by using the Rietveld method. The sII framework contains eight hexakaidecahedral (6 4 5 12 ) cages and 16 smaller dodecahedral (5 12 ) cages per unit cell. The number of D 2 molecules and their distribution in the cages vary systematically with temperature and pressure (Fig.…”

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confidence: 99%

High-pressure/low-temperature neutron scattering of gas inclusion compounds: Progress and prospects

Zhao

Daemen

Lokshin

et al. 2007

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

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Alternative energy resources such as hydrogen and methane gases are becoming increasingly important for the future economy. A major challenge for using hydrogen is to develop suitable materials to store it under a variety of conditions, which requires systematic studies of the structures, stability, and kinetics of various hydrogen-storing compounds. Neutron scattering is particularly useful for these studies. We have developed high-pressure/low-temperature gas/fluid cells in conjunction with neutron diffraction and inelastic neutron scattering instruments allowing in situ and realtime examination of gas uptake/release processes. We studied the formation of methane and hydrogen clathrates, a group of inclusion compounds consisting of frameworks of hydrogen-bonded H2O molecules with gas molecules trapped inside the cages. Our results reveal that clathrate can store up to four hydrogen molecules in each of its large cages with an intermolecular H2-H2 distance of only 2.93 Å. This distance is much shorter than that in the solid/metallic hydrogen (3.78 Å), suggesting a strong densification effect of the clathrate framework on the enclosed hydrogen molecules. The framework-pressurizing effect is striking and may exist in other inclusion compounds such as metal-organic frameworks (MOFs). Owing to the enormous variety and flexibility of their frameworks, inclusion compounds may offer superior properties for storage of hydrogen and/or hydrogen-rich molecules, relative to other types of compounds. We have investigated the hydrogen storage properties of two MOFs, Cu3[Co(CN)6]2 and Cu3(BTC)2 (BTC ‫؍‬ benzenetricarboxylate), and our preliminary results demonstrate that the developed neutron-scattering techniques are equally well suited for studying MOFs and other inclusion compounds.framework-pressurizing effect ͉ hydrogen storage ͉ inelastic neutron scattering ͉ neutron diffraction E ver-increasing fossil energy consumption and associated global environmental concerns have provoked intensive searches for alternative energy resources. Gas hydrates (clathrates) have been proposed as one of these sources of energy; they are crystalline compounds in which a gas molecule guest is physically incorporated into hydrogen-bonded, cage-like ice host frameworks. Natural clathrates have been found worldwide in permafrost and ocean-floor sediments, as well as in the outer solar system (the moon, comets, Mars, satellites of the gas giant planets), and contain primarily methane (CH 4 ) and minor amounts of ethane (C 2 H 6 ), propane (C 3 H 8 ), and other gases (isobutene, normal butane, nitrogen, carbon dioxide, and hydrogen sulfide) (1). Naturally occurring hydrates are difficult to study, and much remains to be learned about their crystal structures, bonding mechanisms, thermodynamics, chemical and mechanical stability, reaction with sediments, and kinetics of formation and decomposition. Hydrogen in the form of H 2 , the most abundant gas in the universe, is considered to be one of the most promising alternatives to fossil energy, beca...

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“…The first structural studies of p-H 2 and o-D 2 at elevated pressures up to 2.5 GPa and low temperatures were made by Ishmaev et al using the neutron diffraction method [5,6]. It was found that the ratio / c a is practically constant and is slightly less than the ideal hcp value (1.631±0.002).…”

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confidence: 99%

“…(6). Then the rotational part of the ground-state energy and the rotational order parameter take the form …”

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Molecular rotation in p-H2 and o-D2 in phase I under pressure

Freǐman

Tretyak

Goncharov

et al. 2011

Low Temperature Physics

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The orientational order parameter, rotational ground-state energy, and lattice distortion parameter (the deviation of the c / a ratio from the ideal hcp value 1.633) in hcp lattice of phase I of p-H 2 and o-D 2 are calculated using a semi-empirical approach. It is shown that the lattice distortion in these J-even species is small compared with that found in n-H 2 , and n-D 2 . The difference presumably is caused by the J-odd species.

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Neutron study of dynamics of solid hydrogen under pressure

Cited by 15 publications

References 3 publications

Sound velocities in solid hydrogen under pressure

Sound velocities in solid hydrogen under pressure

High-pressure/low-temperature neutron scattering of gas inclusion compounds: Progress and prospects

Molecular rotation in p-H2 and o-D2 in phase I under pressure

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