Structural evolution of Li-exchaned natrolite at pressure-induced over-hydration: An X-ray diffraction study

• Published in: Journal of structural chemistry 2016-12, Vol.57 (7), p.1377-1385
• Main Authors: Seryotkin, Yu. V., Likhacheva, A. Yu, Rashchenko, S. V.
• Format: Article
• Language: English
• Subjects: Applications of Synchrotron Radiation in Structural Chemistry; Atomic; Atomic/Molecular Structure and Spectra; Chemistry; Chemistry and Materials Science; Columnar structure; Contact pressure; Diamond anvil cells; Edge joints; Hydration; Inorganic Chemistry; Molecular; Molecular structure; Optical and Plasma Physics; Physical Chemistry; Solid State Physics; Water chemistry; X-ray diffraction
• ISSN: 0022-4766; 1573-8779
• DOI: 10.1134/S0022476616070118

The behavior of Li-exchanged natrolite Li 1.92 Na 0.10 [Al 2.02 Si 2.98 O 10 ]∙2H 2 O 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 Li 2 [Al 2 Si 3 O 10 ]∙6H 2 O 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 H 2 O molecules. Such polyhedra, lining up along the channel axis, are joined through their edges and create a “water” column expanding the structure.