DSC of natural opal: insights into the incorporation of crystallisable water in the opal microstructure

Chauviré, B; Thomas, PS

DSC of natural opal: insights into the incorporation of crystallisable water in the opal microstructure

Chauviré, B Thomas, PS

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Publisher:: Springer Science and Business Media LLC
Publication Type:: Journal Article
Citation:: Journal of Thermal Analysis and Calorimetry, 2020, 140, (5), pp. 2077-2085
Issue Date:: 2020

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Field	Value	Language
dc.contributor.author	Chauviré, B
dc.contributor.author	Thomas, PS
dc.date.accessioned	2020-11-20T00:58:42Z
dc.date.available	2020-11-20T00:58:42Z
dc.date.issued	2020
dc.identifier.citation	Journal of Thermal Analysis and Calorimetry, 2020, 140, (5), pp. 2077-2085
dc.identifier.issn	1388-6150
dc.identifier.issn	1588-2926
dc.identifier.uri	http://hdl.handle.net/10453/144171
dc.description.abstract	© 2019, Akadémiai Kiadó, Budapest, Hungary. Low-temperature DSC on a wide range of opal-A and opal-CT samples was carried out to estimate the proportion of crystallisable water and to determine the size of water-filled cavities. A wide range of crystallisable water contents in the range 4.9 to 41.9% of the water contained in opals were observed, although the proportion of crystallisable water did not correlate with structure. Pore size and pore size distribution were estimated from the melt temperature depression and heat flow data, respectively. Opal-CT was observed to have smaller water-filled pores (radii < 2 nm) than opal-A (radii from 2.5 to 4.9 nm), suggesting that molecular water may be contained between nanograins in the microstructural units (spheres or lepispheres). A narrower pore size distribution was calculated for opal-CT, and no melting of the crystallisable water was observed where bulk water would be expected to melt, suggesting the absence of larger voids. The melting peaks for opal-A, on the other hand, transitioned into the melting of bulk water suggesting the presence of significantly larger water-filled pores, an observation consistent with the microstructure observed in SEM micrographs.
dc.language	en
dc.publisher	Springer Science and Business Media LLC
dc.relation.ispartof	Journal of Thermal Analysis and Calorimetry
dc.relation.hasversion	Accepted Manuscript Version
dc.relation.isbasedon	10.1007/s10973-019-08949-4
dc.rights	info:eu-repo/semantics/openAccess
dc.rights	This is a post-peer-review, pre-copyedit version of an article published in Journal of Thermal Analysis and Calorimetry. The final authenticated version is available online at: https://dx.doi.org/10.1007/s10973-019-08949-4.	en_US
dc.subject	0303 Macromolecular and Materials Chemistry, 0306 Physical Chemistry (incl. Structural), 0399 Other Chemical Sciences
dc.subject.classification	Physical Chemistry
dc.title	DSC of natural opal: insights into the incorporation of crystallisable water in the opal microstructure
dc.type	Journal Article
utslib.citation.volume	140
utslib.for	0303 Macromolecular and Materials Chemistry
utslib.for	0306 Physical Chemistry (incl. Structural)
utslib.for	0399 Other Chemical Sciences
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Strength - CBI - Centre for Built Infrastructure
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Mathematical and Physical Sciences
pubs.organisational-group	/University of Technology Sydney
utslib.copyright.status	open_access	*
pubs.consider-herdc	true
dc.date.updated	2020-11-20T00:58:33Z
pubs.issue	5
pubs.publication-status	Published
pubs.volume	140
utslib.citation.issue	5

Abstract:

© 2019, Akadémiai Kiadó, Budapest, Hungary. Low-temperature DSC on a wide range of opal-A and opal-CT samples was carried out to estimate the proportion of crystallisable water and to determine the size of water-filled cavities. A wide range of crystallisable water contents in the range 4.9 to 41.9% of the water contained in opals were observed, although the proportion of crystallisable water did not correlate with structure. Pore size and pore size distribution were estimated from the melt temperature depression and heat flow data, respectively. Opal-CT was observed to have smaller water-filled pores (radii < 2 nm) than opal-A (radii from 2.5 to 4.9 nm), suggesting that molecular water may be contained between nanograins in the microstructural units (spheres or lepispheres). A narrower pore size distribution was calculated for opal-CT, and no melting of the crystallisable water was observed where bulk water would be expected to melt, suggesting the absence of larger voids. The melting peaks for opal-A, on the other hand, transitioned into the melting of bulk water suggesting the presence of significantly larger water-filled pores, an observation consistent with the microstructure observed in SEM micrographs.

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http://hdl.handle.net/10453/144171