The lattice thermal conductivity of Ge clathrates is investigated by evaluating the linear response theory heat current correlation functions using molecular dynamics. Clathrate crystals with and without guest atoms in their fullerane cages are studied. In comparison with that of diamond-phase Ge, the clathrate conductivity is reduced by approximately 1 order of magnitude due to the open framew...

Raman-scattering spectra of the type II clathrates Cs8Na16Si136 , Cs8Na16Ge136 , and Si136 were studied employing different laser wavelengths. Most of the Raman-active vibrational modes of these compounds were identified. Polarization measurements were used to identify the symmetric modes. The lowest frequency Raman-active optic ‘‘rattle’’ mode corresponding to the vibrations of the Cs atoms in...

Nanosized structures are of intermediate size between individual molecules and bulk materials which gives them several unique properties. At the same time their relative limited sizes make them suitable for studies by the methods of computational chemistry. In this thesis water clusters, ice clathrates and functionalized metal-oxide nanoparticles have been studied by quantumchemical calculation...

Ba-Co-Ge intermetallic clathrates were synthesized in both type-I and chiral-type crystal structures, to investigate thermoelectric and physical properties. Seebeck coe cients, thermal conductivities, electrical resistivities, and Hall coe cients were measured, as well as specific heat and magnetic susceptibility. TypeI Ba8CoxGe46 y was formed with a large number of spontaneous vacancies, simil...