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International Conference on Gas Hydrates (ICGH) (6th : 2008)

A LOW SYMMETRY FORM OF STRUCTURE H CLATHRATE HYDRATE Ripmeester, John A.; Ratcliffe, Christopher I.; Udachin, Konstantin A.

Abstract

In this paper we report a low symmetry version of structure H hydrate that results from the hexagonal form on cooling below 167 K. Phase changes with temperature in the common clathrate hydrates structural families I, II and H have not been observed before, except in doped systems where ordering transitions take place or in the structure I hydrate of trimethylene oxide where the guest molecule dipoles are known to order. Since there is an inverse relationship between the effect of temperature and pressure on ices, it may well be that the low symmetry form reported at low temperature can also be reached by applying high pressure, and that in fact some of the observed high pressure phases are lower symmetry versions of hexagonal sH.

Item Metadata

Title
A LOW SYMMETRY FORM OF STRUCTURE H CLATHRATE HYDRATE
Creator
Ripmeester, John A.; Ratcliffe, Christopher I.; Udachin, Konstantin A.
Contributor
University of British Columbia. Department of Chemical and Biological Engineering; International Conference on Gas Hydrates (6th : 2008 : Vancouver, B.C.)
Date Issued
2008-07
Description
In this paper we report a low symmetry version of structure H hydrate that results from the hexagonal form on cooling below 167 K. Phase changes with temperature in the common clathrate hydrates structural families I, II and H have not been observed before, except in doped systems where ordering transitions take place or in the structure I hydrate of trimethylene oxide where the guest molecule dipoles are known to order. Since there is an inverse relationship between the effect of temperature and pressure on ices, it may well be that the low symmetry form reported at low temperature can also be reached by applying high pressure, and that in fact some of the observed high pressure phases are lower symmetry versions of hexagonal sH.
Extent
376408 bytes
Subject
High pressure; Phase change; Symmetry; Low temperature; H hydrate
Genre
Conference Paper
Type
Text
File Format
application/pdf
Language
eng
Date Available
2008-07-23
Provider
Vancouver : University of British Columbia Library
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International
DOI
10.14288/1.0040939
URI
http://hdl.handle.net/2429/1091
Affiliation
Non UBC
Citation
Udachin, Konstantin A.; Ratcliffe, Christopher I.; Ripmeester, John A. 2008. A LOW SYMMETRY FORM OF STRUCTURE H CLATHRATE HYDRATE. Proceedings of the 6th International Conference on Gas Hydrates (ICGH 2008), Vancouver, British Columbia, CANADA, July 6-10, 2008.
Peer Review Status
Unreviewed
Copyright Holder
Ripmeester, John A.
Rights URI
http://creativecommons.org/licenses/by-nc-nd/4.0/
Aggregated Source Repository
DSpace

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Attribution-NonCommercial-NoDerivatives 4.0 International