Anisotropic lattice expansion of structure H clathrate hydrates induced by help guest

Experiments and molecular dynamics simulations

Kotaro Murayama, Satoshi Takeya, Saman Alavi, Ryo Ohmura

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

The structure H (sH) clathrate hydrates of neo-hexane with argon, krypton, and methane help gases are synthesized to study the effect of the help gas on the crystal lattice structure. Powder X-ray diffraction (PXRD) measurements on these hydrates were performed for temperatures in the range of 93-183 K, and the a-axis and c-axis lattice constants and the small and medium sH cage occupancies were determined. The PXRD results show that the a-axis lattice constants of the three clathrate hydrates are close in magnitude, but at each temperature, for the c-axis lattice constants c(CH4) > c(Kr) > c(Ar). Parrinello-Rahman molecular dynamics (MD) simulations were performed on the three sH clathrate hydrate phases. The PXRD observed trends in the a-axis and c-axis lattice constants at different temperatures were reproduced by the simulations. The dynamics of the small cage guests are characterized by the velocity autocorrelation functions. The experiments and computations show the complex interplay of the molecular size and interaction energies in determining the lattice structure and stability of even relatively simple clathrate hydrates of nonpolar, hydrophobic molecules.

Original languageEnglish
Pages (from-to)21323-21330
Number of pages8
JournalJournal of Physical Chemistry C
Volume118
Issue number37
DOIs
Publication statusPublished - 2014 Sep 18

Fingerprint

clathrates
Hydrates
hydrates
Molecular dynamics
Lattice constants
molecular dynamics
expansion
X ray powder diffraction
Computer simulation
simulation
Experiments
Gases
Krypton
diffraction
Argon
Methane
Hexanes
Hexane
x rays
Autocorrelation

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Energy(all)

Cite this

Anisotropic lattice expansion of structure H clathrate hydrates induced by help guest : Experiments and molecular dynamics simulations. / Murayama, Kotaro; Takeya, Satoshi; Alavi, Saman; Ohmura, Ryo.

In: Journal of Physical Chemistry C, Vol. 118, No. 37, 18.09.2014, p. 21323-21330.

Research output: Contribution to journalArticle

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