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American Mineralogist

Journal of Earth and Planetary Materials

Ed. by Baker, Don / Xu, Hongwu / Swainson, Ian


IMPACT FACTOR 2017: 2.645

CiteScore 2018: 2.55

SCImago Journal Rank (SJR) 2018: 1.355
Source Normalized Impact per Paper (SNIP) 2018: 1.103

Online
ISSN
1945-3027
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Volume 92, Issue 10

Issues

Pressure-induced over-hydration of thomsonite: A synchrotron powder diffraction study

Anna Yu. Likhacheva / Yuriy V. Seryotkin / Andrey Yu. Manakov / Sergey V. Goryainov / Aleksey I. Ancharov / Mikhail A. Sheromov
  • Budker Institute of Nuclear Physics SibD RAS, ac.Lavrentieva av. 11, 630090 Novosibirsk, Russia
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Published Online: 2015-04-01 | DOI: https://doi.org/10.2138/am.2007.2566

Abstract

The structural behavior of thomsonite compressed in aqueous medium up to 3 GPa was studied by means of in situ synchrotron powder diffraction with a diamond anvil cell. In the range between 0.0001 and 2 GPa, the compressibility of thomsonite is markedly lower than that reported previously, where a non-penetrating medium (with only 6% H2O) was used. This indicates a pressure-induced hydration (PIH), which results in the transition to an over-hydrated phase observed at 2 GPa. The structure of over-hydrated thomsonite contains one additional, half-occupied H2O position, coordinated by the calcium at the Ca2 site, with a scolecite-like coordination [CaO4(H2O)3]. The appearance of new H2O position causes a 4.5% volume expansion through the cooperative rotation of [T2O5] chains, leading to the enlargement of the cross-section of the main channels parallel to c axis. The observed deformation mechanism is similar to that found in high-hydrated and super-hydrated natrolite, although only a half of the channels are affected by PIH. The present data indicate that the over-hydration effect in fibrous zeolites strongly depends on the partial water pressure in compressing medium.

Keywords: Zeolite; thomsonite; high pressure; compressibility; phase transition; crystal structure; over-hydration

About the article

Received: 2007-01-17

Accepted: 2007-05-21

Published Online: 2015-04-01

Published in Print: 2007-10-01


Citation Information: American Mineralogist, Volume 92, Issue 10, Pages 1610–1615, ISSN (Online) 1945-3027, ISSN (Print) 0003-004X, DOI: https://doi.org/10.2138/am.2007.2566.

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