Structural evolution of Li-exchaned natrolite at pressure-induced over-hydration: An X-ray diffraction study |
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Authors: | Yu V Seryotkin A Yu Likhacheva S V Rashchenko |
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Institution: | 1.Sobolev Institute of Geology and Mineralogy, Siberian Branch,Russian Academy of Sciences,Novosibirsk,Russia;2.Novosibirsk National Research State University,Novosibirsk,Russia;3.Budker Institute of Nuclear Physics, Siberian Branch,Russian Academy of Sciences,Novosibirsk,Russia |
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Abstract: | The behavior of Li-exchanged natrolite Li1.92Na0.10Al2.02Si2.98O10]?2H2O at compression in penetrating (water-containing) medium was studied by in situ synchrotron powder diffraction in diamond anvil cell up to 2.5 GPa. Within 0-1.3 GPa the compression is almost isotropic, and upon the further pressure increase the sample undergoes additional hydration, leading to abrupt volume expansion by 22%, a record value for natrolite. In the proposed model for the high-pressure phase Li2Al2Si3O10]?6H2O the Li+ cations have no contact with the framework O-atoms and are surrounded by “water-jacket” in the form of semi-octahedron (tetragonal pyramid) composed of five H2O molecules. Such polyhedra, lining up along the channel axis, are joined through their edges and create a “water” column expanding the structure. |
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