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Neutron scattering ...
Neutron scattering study of polyamorphic THF ∙ (H2O)17 – toward a generalized picture of amorphous states and structures derived from clathrate hydrates
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- Barros Brant Carvalho, Paulo Henrique (author)
- Stockholms universitet,Institutionen för material- och miljökemi (MMK),Ulrich's group
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- Ivanov, Mikhail (author)
- Stockholms universitet,Institutionen för material- och miljökemi (MMK)
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- Andersson, Ove (author)
- Department of Physics, Umeå University
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- Loerting, Thomas (author)
- Institute of Physical Chemistry, University of Innsbruck
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- Bauer, Marion (author)
- Institute of Physical Chemistry, University of Innsbruck
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- Tulk, Chris A. (author)
- Neutron Scattering Division, Oak Ridge National Laboratory
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- Haberl, Bianca (author)
- Neutron Scattering Division, Oak Ridge National Laboratory
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- Daemen, Luke L. (author)
- Neutron Scattering Division, Oak Ridge National Laboratory
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- Molaison, Jamie J. (author)
- Neutron Scattering Division, Oak Ridge National Laboratory
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- Amann-Winkel, Katrin (author)
- Stockholms universitet,Fysikum
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- Lyubartsev, Alexander P., 1962- (author)
- Stockholms universitet,Avdelningen för fysikalisk kemi,Fysikum,Science for Life Laboratory (SciLifeLab)
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- Bull, Craig L. (author)
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory
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- Funnell, Nicholas P. (author)
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory
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- Häussermann, Ulrich, 1964- (author)
- Stockholms universitet,Avdelningen för oorganisk kemi och strukturkemi
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(creator_code:org_t)
- English.
- Related links:
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https://urn.kb.se/re...
Abstract
Subject headings
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- From crystalline tetrahydrofuran clathrate hydrate, THF-CH (THF ∙ 17H2O, cubic structure II), three distinct polyamorphs can be derived. First, THF-CH undergoes pressure-induced amorphization when pressurized to 1.3 GPa in the temperature range 77–140 K to a form which, in analogy to pure ice, may be called high-density amorphous (HDA). Second, HDA can be converted to a densified form, very-HDA (VHDA), upon heat-cycling at 1.8 GPa to 180 K. Decompression of VHDA to atmospheric pressure below 130 K produces the third, recovered amorphous (RA) form. Results from a compilation of neutron scattering experiments and molecular dynamics simulations provide a generalized picture of the structure of amorphous THF hydrates with respect to crystalline THF-CH and liquid THF ∙ 17H2O solution (~2.5 M). The calculated density of (only in situ observable) HDA and VHDA at 2 GPa and 130 K is 1.287 and 1.328 g/cm3, respectively, whereas that of RA (at 1 atm) is 1.081 g/cm3. Although fully amorphous, HDA is heterogeneous with two length scales for water-water correlations (less dense local water structure) and guest-water correlations (denser THF hydration structure). The hydration structure of THF is influenced by guest-host hydrogen bonding. THF molecules maintain a quasiregular array, reminiscent of the crystalline state, and their hydration structure (out to 5 Å) constitutes ~23 H2O. The local water structure in HDA is reminiscent of pure HDA-ice, featuring 5-coordinated H2O. In VHDA, this structure is maintained but the local water structure is densified to resemble pure VHDA-ice with 6-coordinated H2O. The hydration structure of THF in RA constitutes ~18 H2O and the water structure corresponds to a strictly 4-coordinated network, as in the liquid. Both VHDA and RA can be considered as homogeneous, solid solutions of THF and water. The local water structure of water-rich (1:17) amorphous CHs resembles most that of the corresponding amorphous water ices when compared to guest-rich CHs, e.g., Ar ∙ ~6H2O. The proposed significance of different contributions of water local environments presents a simple view to justify neutron structure factor features.
Subject headings
- NATURVETENSKAP -- Fysik -- Den kondenserade materiens fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Condensed Matter Physics (hsv//eng)
Keyword
- Clathrate Hydrate
- Amorphous
- Neutron Diffraction
- Physical Chemistry
- fysikalisk kemi
- materialkemi
- Materials Chemistry
Publication and Content Type
- vet (subject category)
- ovr (subject category)
To the university's database
- By the author/editor
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Barros Brant Car ...
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Ivanov, Mikhail
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Andersson, Ove
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Loerting, Thomas
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Bauer, Marion
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Tulk, Chris A.
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Haberl, Bianca
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Daemen, Luke L.
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Molaison, Jamie ...
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Amann-Winkel, Ka ...
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Lyubartsev, Alex ...
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Bull, Craig L.
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Funnell, Nichola ...
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Häussermann, Ulr ...
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- About the subject
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Physical Science ...
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and Condensed Matter ...
- By the university
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Stockholm University