Raman spectroscopy of chibaite, natural MTN silica clathrate, at high pressure up to 8 GPa

Anna Yu Likhacheva, Sergey V. Goryainov, Yuriy V. Seryotkin, Konstantin D. Litasov, Koichi Momma

Результат исследования: Научные публикации в периодических изданияхстатьярецензирование

6 Цитирования (Scopus)

Аннотация

The high-pressure behavior of chibaite, newly discovered natural clathrasil isotypical to gas hydrate sII, with ideal formula 136SiO2·24X (X = CH4, C2H6, C3H8, C4H10), was studied by Raman spectroscopy up to 7.7 GPa with a diamond anvil cell, using KBr as a pressure transmitting medium. The chibaite structure is preserved throughout the whole pressure range. The deviation from regular shift and appearance of new bands in the lattice spectrum is observed at about 1.2 and 3.5 GPa. As concerns the guest hydrocarbon molecules, the high-frequency shifts of their C-C and C-H bands are almost monotonic within the whole pressure range, showing only slight bends at 1.2 and 3.5 GPa. The FWHMs of stretching C-C and C-H bands demonstrate a high sensitivity to pressure, more pronounced at 1.2 GPa. The obtained data allow to suggest two reversible structural transformations in chibaite at about 1.2 and 3.5 GPa, associated with the distortion of framework cages and corresponding ordering of the guest hydrocarbon molecules. The role of 'guest molecule/host cage' dimensional ratio determining the HP behavior of MEP and MTN clathrasils is discussed.

Язык оригиналаанглийский
Страницы (с-по)100-106
Число страниц7
ЖурналMicroporous and Mesoporous Materials
Том224
DOI
СостояниеОпубликовано - 1 апр 2016

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