Dehydration and thermal stability of elpidite: An in-situ single crystal X-ray diffraction study

Cametti, Georgia; Armbruster, Thomas Michael; Nagashima, Mariko (2016). Dehydration and thermal stability of elpidite: An in-situ single crystal X-ray diffraction study. Microporous and mesoporous materials, 227, pp. 81-87. Elsevier 10.1016/j.micromeso.2016.02.049

Text Elpidite_MMM2016.pdf - Published Version Restricted to registered users only Available under License Publisher holds Copyright. Download (1MB) | Request a copy

Elpidite Na2ZrSi6O15·3H2O is a natural zirconosilicate with space group Pbcm. A sample from Mt. Saint Hilaire (Canada) was investigated between 25 and 350 °C under different humidity conditions (RH = 0% and at RH = 100%). The largest structural channels are eight- and ten-rings delimited by corner-sharing SiO4 tetrahedra and ZrO6 octahedra.

Under dry conditions, the structure started liberating water at 75 °C. At 100 °C, when it lost one H2O molecule, elpidite underwent a structural change from space group Pbcm to Cmce.

The structure continuously released water up to 225 °C until it became anhydrous. From 225 °C to 350 °C no structural changes were observed. Associated with the transition from Pbcm to Cmce symmetry, the unit-cell volume reduced by 2.7%. An additional decrease is observed up to 225 °C when the contraction reached 3.4% of the starting volume. After release of all H2O molecules, increase of temperature led to gradual expansion of the unit cell from 2940.79 (7) Å3 at 225 °C to 2947.4 (5) Å3 at 350 °C.

Supplementary ex-situ heating experiments showed that the structure was retained up to 950 °C but after heating at 1200 °C the sample melted.

Under humid conditions a dehydration-trend similar to that found under a dry N2-atmosphere was observed but the structural changes occurred at slightly higher temperatures.

Immersion of a dehydrated sample in water for 30 days led to only marginal rehydration and the Cmce symmetry was preserved.

Interest & Impact

Downloads

1 since deposited on 07 Jun 2017
0 in the past 12 months

Citations

5 Citations in Web of Science ®
6 Citations in Scopus

Search

in Google Scholar™

Services

Actions (login required)

Edit item

Actions (login required)

Edit item