The structures of crystalline hydrogen bromide

Cockcroft, J. Κ.; Simon, A.; Ziebeck, K.R.A.

doi:10.1524/zkri.1988.184.14.229

Cited by 3 publications

(3 citation statements)

References 17 publications

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“…For orientationally disordered phases, it is possible to characterize the scattering density by use of symmetry-adapted spherical-harmonic (SASH) functions, whose coefficients can be refined from the neutron diffraction data, as was done for the high-temperature solid phases of SF 6 (Cockcroft and Fitch, 1988) and DBr (Cockcroft, Simon and Ziebeck, 1988 a). Three phases are identified for D 2 S, in agreement with the earlier experimental work, and their structures have been refined from high-resolution powder neutron diffraction data.…”

Section: Introductionsupporting

confidence: 54%

The solid phases of deuterium sulphide by powder neutron diffraction

Cockcroft¹,

Fitch²

1990

Zeitschrift Für Kristallographie - Crystalline Materials

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Powder neutron diffraction studies confirm that D 2 S has 3 solidstate phases at ambient pressure. Phases I and II are cubic and orientationally disordered with space groups Fm3m (a = 5.8486(8) Ä at 160 K) and Pah (a = 5.7647(6) Ä at 120 K), respectively. The deuterium scattering density arising from the disorder is modelled using symmetry-adapted spherical harmonic functions, which show a reduction from "twelve-fold" to "sixfold" disorder on cooling from phase I to phase II. For the fully ordered low-temperature phase III, a new structure has been determined which bears little resemblance to that reported in a previous neutron diffraction study. The structure is orthorhombic, space group Pbcm, with a = 4.0760(1) Ä, b = 13.3801(5) Ä and c = 6.7215(3) A at 1.5 K. The structure is essentially hexagonally close-packed, with distortions to accommodate the hydrogen atoms. The structure is antiferroelectric with the alignment of the molecular dipoles along the a direction.

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Section: Introductionsupporting

confidence: 54%

The solid phases of deuterium sulphide by powder neutron diffraction

Cockcroft¹,

Fitch²

1990

Zeitschrift Für Kristallographie - Crystalline Materials

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“…Given the great improvements in flux and resolution of neutron powder diffractometers since the earlier studies, and the ability to refine complex crystal structures from good quality powder diffraction data using the Rietveld (1969) method, we felt that a more accurate determination of the solid state structures of an important molecule such as DzS was appropriate. For orientationally disordered phases, it is possible to characterize the scattering density by use of symmetry-adapted spherical-harmonic (SASH) functions, whose coefficients can be refined from the neutron diffraction data, as was done for the high-temperature solid phases of SF 6 (Cockcroft and Fitch, 1988) and DBr (Cockcroft, Simon and Ziebeck, 1988 a). Three phases are identified for DzS, in agreement with the earlier experimental work, and their structures have been refined from high-resolution powder neutron diffraction data.…”

Section: Introductionsupporting

confidence: 53%

The solid phases of deuterium sulphide by powder neutron diffraction

Cockcroft¹,

Fitch²

1990

Zeitschrift für Kristallographie

View full text Add to dashboard Cite

Powder neutron diffraction studies confirm that DzS has 3 solidstate phases at ambient pressure. Phases I and II are cubic and orientationally disordered with space groups Fm3m (a = 5.8486(8) A at 160 K) and Pa3 (a = 5.7647(6) A at 120 K), respectively. The deuterium scattering density arising from the disorder is modelled using symmetry-adapted spherical harmonic functions, which show a reduction from "twelve-fold" to "sixfold" disorder on cooling from phase I to phase II. For the fully ordered low-temperature phase III, a new structure has been determined which bears little resemblance to that reported in a previous neutron diffraction study. The structure is orthorhombic, space group Pbcm, with a = 4.0760(1) A, b = 13.3801(5) A and c = 6.7215(3) A at 1.5 K. The structure is essentially hexagonally close-packed, with distortions to accommodate the hydrogen atoms. The structure is anti ferroelectric with the alignment of the molecular dipoles along the a direction.

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“…Neutron diffraction of deuterated powder samples generally provides reliable hydrogen positions; however, unexpected structural transitions may occur on deuteration due to isotope effects. 9,10 Calculations of the lattice energy of computationally generated crystal structures are very sensitive to hydrogen positions and offer the possibility, by combination with conventional structure determination methods, to provide a more accurate determination of hydrogen positions.…”

Section: Introductionmentioning

confidence: 99%