Transformation pathways and isothermal compressibility of a MTN-type clathrasil using penetrating and non-penetrating fluids
- Author(s)
- Katharina Sarah Scheidl, Herta Silvia Effenberger, Takehiko Yagi, Koichi Momma, Ronald Miletich
- Abstract
The high-pressure behavior of the natural MTN-type clathrasil chibaite was investigated with in situ single crystal X-ray diffraction and Raman spectroscopy under hydrostatic pressures up to 10.3 GPa. The experiments were conducted in diamond-anvil cells using 4:1 methanol-ethanol mixture (ME), helium (He) and neon (Ne) as pressure-transmitting media. The pressure dependent unit-cell volumes of the room-pressure polymorph yield an isothermal bulk modulus K-T0 = 25.75 (19) GPa for the compression in the non-penetrating ME fluid. Due to the penetration of the Ne and He atoms into the cages of the framework, the crystal structure is significantly stiffened resulting in K-T0 = 42.5 (1.2) GPa (Ne) and K-T0 = 58 (2) GPa (He). Under the influence of pressure both the evolution of the Raman spectra and the change in cell metrics indicate a distortion of the lattice without leading to a complete pressure-induced amorphization, as observed for many comparable porous structures. Compressed in the non-penetrating ME, the cubic Fd (3) over barm framework of chibaite undergoes a first transformation step in the pressure range between L7 GPa and 2.2 GPa and a second one between 3.9 GPa and 4.3 GPa. The accompanied formation of crystal domains did not allow a reliable determination of the distorted crystal structures. The unit cell parameters might suggest a monoclinic metric for pressures > 1.7 GPa and a monoclinic or tetragonal metric for pressures > 3.9 GPa. However, in some samples even the co-existence of crystal domains of a different degree of lattice distortions has been proved.
- Organisation(s)
- Department of Mineralogy and Crystallography
- External organisation(s)
- University of Tokyo, National Museum of Nature and Science
- Journal
- Microporous and Mesoporous Materials
- Volume
- 273
- Pages
- 73-89
- No. of pages
- 17
- ISSN
- 1387-1811
- DOI
- https://doi.org/10.1016/j.micromeso.2018.06.033
- Publication date
- 01-2019
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 104026 Spectroscopy, 104011 Materials chemistry, 105113 Crystallography
- Keywords
- ASJC Scopus subject areas
- Condensed Matter Physics, Mechanics of Materials, Chemistry(all), Materials Science(all)
- Portal url
- https://ucris.univie.ac.at/portal/en/publications/transformation-pathways-and-isothermal-compressibility-of-a-mtntype-clathrasil-using-penetrating-and-nonpenetrating-fluids(f28e987a-8913-42de-93e9-0589bacf0862).html