Disorder of Hydrofluorocarbon Molecules Entrapped in the Water Cages of Structure I Clathrate Hydrate

Structure and Density Comparison of Noble Gas Hydrates Encapsulating Xenon, Krypton and Argon

Understanding the effect of guest species on the host framework is important for the development of structure-based properties of inclusion compounds. Herein, the crystal structures of the noble gas hydrates encapsulating Xe, Kr, and Ar were studied by powder X-ray diffraction measurements. The crystal structures and hydration numbers of these noble gas hydrates were solved by Rietveld refinements using optimized models with the direct-space technique. It was revealed that host cage size of these hydrates changed depending on the type of guest species even though their unit-cell parameters were the same. Based on the structure models obtained, the densities of Xe, Kr, and Ar gas hydrates were also determined to be 1.837, 1.445 and 1.097 g/cm³ at 93 K, respectively. Our findings, from a crystallographic point of view, may give insight into further understanding the thermodynamic stability and physical properties of gas hydrates encapsulating small guests.

Stability and characterization of the structure II binary clathrate hydrate of the refrigerant trans-1,3,3,3-tetrafluoropropene + methane

A new clathrate hydrate formed with trans-1,3,3,3-tetrafluoropropene and methane was characterized by phase equilibrium and PXRD measurements and MD simulations.