It is shown that the temperature dependence of Langmuir constants contains all the information needed to determine spherically averaged intermolecular potentials. An analytical “inversion” method based on the standard statistical model of van der Waals and Platteeuw is presented which extracts cell potentials directly from experimental data. The method is applied to ethane and cyclopropane clat...

In this Letter we present a calculation of the temperature-pressure phase diagram of Si in a range of pressures covering from -5 to 20 GPa and temperatures up to the melting point. The phase boundaries and triple points between the diamond, liquid, beta-Sn, and Si34 clathrate phases are reported. We have employed efficient simulation techniques to calculate free energies and to numerically inte...

A new clathrate [K(H(2)O)(n)][CuZn(CN)(4)] has been synthesized and its host structure has been determined by the single-crystal X-ray diffraction method. It has a [CuZn(CN)(4)](-) tridymite-like 3D framework host, formed with tetrahedral Cu(I) and Zn(II) ions and cyanide bridges and includes water molecules as guests, together with K(+). This tridymite-like structure is the first structural va...

To investigate factors influencing nucleation of air clathrate hydrates in polar ice sheets, we have performed high-resolution mapping of the distributions of soluble impurities, air bubbles and airhydrate crystals versus depth in the Dome Fuji Antarctic ice. Significant correlation observed between the concentrations of air inclusions and impurities in ice along with frequent occurrence of imp...

In this communication, the charge transfer phenomenon from ionic host lattice to nonionic guest molecule was observed by magnetization and Raman spectroscopy measurements for nonionic and ionic clathrate hydrates. The present findings on the magnetic property of nonionic guest molecules in ionic hydrate might provide important information on the unrevealed nature of host-guest interaction in io...

First posted September 8, 2023 For additional information, contact: Earthquake Science CenterU.S. Geological Survey350 N. Akron RoadMoffett Field, CA 94035 The U.S. Survey (USGS) Clathrate Hydrate Properties Project, active from 1993 to 2022 in Menlo Park, California, stemmed an earlier project on the properties of planetary ices supported by National Aeronautics and Space Administration’s (NAS...

The thermodynamics of binary sII hydrogen clathrates with secondary guest molecules is studied with Monte Carlo simulations. The small cages of the sII unit cell are occupied by one H(2) guest molecule. Different promoter molecules entrapped in the large cages are considered. Simulations are conducted at a pressure of 1000 atm in a temperature range of 233-293 K. To determine the stabilizing ef...

Abstract Clathrate hydrates may represent a sizable fraction of material within the icy shells Kuiper Belt objects and moons. They influence chemical thermal evolution subsurface oceans by locking volatiles into ice shell providing more insulation than pure water ice. We model formation these crystalline compounds in conditions relevant to outer solar system objects, using Pluto as an example. ...

Carbon monoxide clathrate hydrate is a potentially important constituent in the solar system. In contrast to the well-established relation between the size of gaseous molecule and hydrate structure, previous work showed that carbon monoxide molecules preferentially form structure-I rather than structure-II gas hydrate. Resolving this discrepancy is fundamentally important to understanding clath...

The significance of clathrate hydrates lies in their ability to encapsulate a vast range of inert gases. Although the natural abundance of a few noble gases (Kr and Xe) is poor their hydrates are generally abundant. It has already been reported that HF doping enhances the stability of hydrogen hydrates and methane hydrates, which prompted us to perform a model study on helium, neon and argon hy...