We investigate the role of rattling guest atoms on the lattice thermal conductivity of a type-I clathrate Ba_{8}Ga_{16}Ge_{30} by first-principles lattice dynamics. Comparing phonon properties of filled and empty clathrates, we show that rattlers cause tenfold reductions in the relaxation time of phonons by increasing the phonon-phonon scattering probability. Contrary to the resonant scattering...

One explanation for the abrupt increases in atmospheric CH4, that occurred repeatedly during the last glacial cycle involves clathrate destabalization events. Because marine clathrates have a distinct deuterium/hydrogen (D/H) isotope ratio, any such destabilization event should cause the D/H ratio of atmospheric CH4 (deltaD(CH4)) to increase. Analyses of air trapped in the ice from the second G...

We present a joint experimental and theoretical study of the superconductivity in doped silicon clathrates. The critical temperature in Ba(8)@Si-46 is shown to strongly decrease with applied pressure. These results are corroborated by ab initio calculations using MacMillan's formulation of the BCS theory with the electron-phonon coupling constant lambda calculated from perturbative density func...

The effect of macrocycle size on the structure-property relationships was studied for inclusion compounds of tert-butylcalix[n]arenes (n=4,5) with volatile organic guests having various molecular size and group composition. Vapor-sorption isotherms, guest-inclusion stoichiometry and Gibbs energy, thermostability parameters and decomposition enthalpies were determined for host-guest compounds (c...

The stability of the recently characterized type II hydrogen clathrate [Mao, W. L., Mao, H.-K., Goncharov, A. F., Struzhkin, V. V., Guo, Q., et al. (2002) Science 297, 2247-2249] with respect to hydrogen occupancy is examined with a statistical mechanical model in conjunction with first-principles quantum chemistry calculations. It is found that the stability of the clathrate is mainly caused b...

The supersolar abundances of volatiles observed in giant planets suggest that a compositional gradient was present at the time their formation protosolar nebula. To explain this gradient, several studies have investigated radial transport trace species and effect icelines on abundance profiles solids vapors formed disk. However, these models only consider presence forms pure condensates or amor...

Methane can be stored in tea clathrates, that is kinetics of methane clathrate formation can be significantly accelerated (90% saturation uptake in 20 min) by ingredients (polyphenols and saponins) in tea infusions with a volumetric capacity of up to 172 v/v.

Clathrate compounds combine aesthetic beauty of their crystal structures with promising thermoelectric properties that have made them one of the most explored family of compounds deemed as base for thermoelectric generators for midand hightemperature application. This chapter surveys crystal and electronic structure and structure-related transport properties of selected types of clathrates and ...