Crystal Structure of Hydrogen Isotopes

Bostanjoglo, O.; Kleinschmidt, Ralph

doi:10.1063/1.1840975

Cited by 45 publications

(13 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

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“…In order to probe the geometrical nature of the frustration in this class of systems, a number of studies of solid hydrogen in restricted geometries ͑adsorbed films [10][11][12][13][14][15][16] and porous materials [17][18][19] ͒ have been carried out to examine the effects of reduced dimensions, geometrical constraints, and substrate interactions on the orientational ordering. Carefully grown films [20][21][22] form hcp structures, and the increased ZPM in the outer layers 23 combined with the frustration of the hcp structure apparently prevents longrange ordering, and complete periodic ordering for the molecular orientations has not been observed for these films.…”

Section: Introductionmentioning

confidence: 99%

Orientational ordering in films of molecular hydrogen on boron nitride: Thick (12-layer) films and bilayer films

Kim

Sullivan

1998

Phys. Rev. B

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We report NMR studies of the orientational ordering of molecular hydrogen in films physisorbed on hexagonal boron nitride ͑BN͒. The local orientational ordering of the molecular axes is determined for both thick films ͑12 layers͒ and thin films ͑bilayers͒. The ordering observed is in both cases very different from that observed for bulk solid hydrogen. Quadrupolar glass ordering occurs for intermediate layers in thick films at low ortho concentrations 0.25ϽXϽ0.40 and Tр0.7 K. The ortho molecules remain rotationally disordered in the outer layers of the thick films and invariant to small changes in thickness. In the bilayers one observes a long range ordering for Tр1.95 K and Xр0.56, and a quadrupolar glass ordering for intermediate concentrations (0.37ϽXϽ0.55) and intermediate temperatures (0.

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Section: Introductionmentioning

confidence: 99%

Orientational ordering in films of molecular hydrogen on boron nitride: Thick (12-layer) films and bilayer films

Kim

Sullivan

1998

Phys. Rev. B

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“…5 Also, thin ͑ϳ10 nm͒ films deposited below ϳ0.4 T tp have shown metastable fcc structure. 6,7 Finally, thin hydrogen films grown from the vapor or liquid can take on the lattice structure of the substrate. 8 We will fill a gap in this literature by describing the temperature dependence and the crystal morphology of the metastable phases in Jϭ0 H 2 and D 2 .…”

Section: Introductionmentioning

confidence: 99%

Metastable structures of solid hydrogen

et al. 1996

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The Jϭ0→2 Raman signal from solid Jϭ0 D 2 or H 2 reveals the hcp structure when deposited at a rate 0.1рR͑m/min͒р40 onto MgF 2 at T d /T tp Ͼ0.3, a mixture of hcp and fcc crystals at 0.2ϽT d /T tp Ͻ0.3 and possibly a randomly stacked close-packed structure at T d /T tp Ͻ0.2, where T tp is the triple point temperature. Non-hcp crystals transform to hcp continuously and irreversibly with increasing T. Finally, the crystal size decreases with decreasing T d and increasing R, from ϳ1 mm at T d ϳ0.8T tp and Rϳ2 m/min to ϳ1 m at 0.25 T tp and Rϳ40 m/min.

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“…Generally, the corrected data are consistent with the extrapolated results of the present measurements. However, there are relatively large experimental uncertainties associated with most of the earlier work [60][61][62][63]. The data of Nielsen [64] and Yarnell et al [65] are more precise.…”

Section: Cp(tp)mentioning

confidence: 69%

“…It is possible to compare this value with the result of existing x-ray [60], electron [61], and neutron scattering experiments [62][63][64][65] on the low-pressure solid.…”

Section: Cp(tp)mentioning

confidence: 99%

See 1 more Smart Citation

Pressure-Volume-Temperature Relationships for Normal Deuterium Between 18.7 and 21.0 K

Schwalbe¹,

Grilly²

1984

J. RES. NATL. BUR. STAN.

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Analytical expressions are derived for the melting line and liquid equation of state of normal deuterium near the triple point. Melting pressures were measured between the triple point and 20.4 K. These results combined with existing pressure measurements along the saturated liquid-vapor curve fix an accurate value. Ttp =j118. 723 K, for the triple-point temperature. Data for the isothermal compressibility and thermal expansion coefficients of the liquid were taken over the temperature and pressure ranges 18.8 to 21.0 K and 4 to 70 bar, respectively. The liquid molar volume was measured at nine points below 20.4 K. All liquid PVT data are shown to be internally consistent. Measurements of the volume changes on melting are also presented. The heat of fusion and the solid molar volume at melting are deduced from these data. Also included are detailed comparisons of our results with existing data. A critical appraisal is given of all measured thermodynamic quantities in this regime.

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Crystal Structure of Hydrogen Isotopes

Cited by 45 publications

References 10 publications

Orientational ordering in films of molecular hydrogen on boron nitride: Thick (12-layer) films and bilayer films

Orientational ordering in films of molecular hydrogen on boron nitride: Thick (12-layer) films and bilayer films

Metastable structures of solid hydrogen

Pressure-Volume-Temperature Relationships for Normal Deuterium Between 18.7 and 21.0 K

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