We report a new hydrogen clathrate hydrate synthesized at 1.2 GPa and 298 K documented by single-crystal X-ray diffraction, Raman spectroscopy, and first-principles calculations. The oxygen sublattice of the new clathrate hydrate matches that of ice II, while hydrogen molecules are in the ring cavities, which results in the trigonal R3c or R-3c space group (proton ordered or disordered, respectively) and the composition of (H2O)6H2. Raman spectroscopy and theoretical calculations reveal a hydrogen disordered nature of the new phase C1', distinct from the well-known ordered C1 clathrate, to which this new structure transforms upon compression and/or cooling. This new clathrate phase can be viewed as a realization of a disordered ice II, unobserved before, in contrast to all other ordered ice structures.
@article{arxiv.2007.09472,
title = {Novel hydrogen clathrate hydrate},
author = {Yu Wang and Konstantin Glazyrin and Valery Roizen and Artem Oganov and Ivan Chernyshov and Xiao Zhang and Eran Greenberg and Vitali B. Prakapenka and Xue Yang and Shu-qing Jiang and Alexander F. Goncharov},
journal= {arXiv preprint arXiv:2007.09472},
year = {2021}
}
Comments
9 pages, 4 figures, 1 table; Supplementary materials: Materials and Methods, Supplementary Figures S1-S8, Tables S1-S3, and Bibliography with 18 References