Dresden 2006 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 7: Superconductivity & Solids At Low Temperature - Poster Session

TT 7.72: Poster

Montag, 27. März 2006, 14:00–17:45, P1

Thermal conductivity of gas clathrate hydrates at low temperatures — •Olesya Romantsova, Alexander Krivchikov, Gorodilov Boris, Korolyuk Oksana, and Manzhelii Vadim — B.Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine

Clathrate hydrates are open polymorphous crystal structures related to ordinary ice. However, κ(T) of gas hydrates is similar to glass. The understanding of the causes responsible for the glass-like behavior in gas hydrates will be helpful in finding a microscopic mechanism of the thermal transport in disordered solids.
The thermal conductivity of the THF and xenon hydrates has been measured using the steady-state technique in the intervals 2-220 K and 2-170 K, respectively. Two samples of THF hydrate were grown in the measuring cell during 7 min (fast cooling) and 70 min (slow cooling). For the sample of THF hydrate (slow cooling) in the interval 15-97 K and for xenon hydrate in the interval 56-97 K the behavior of κ(T) shows an anomaly: the thermal conductivity decreases by almost over 50 per cent as the temperature increases. This observation is attributed to the consequence of resonant scattering where the coupling of the lattice with No-dqrattlingNo-dq motions of Xe dominates the thermal resistivity at high temperature. The thermal conductivity in the low temperature regime is found to follow the prediction of the soft-potential model. The comparative analysis of the thermal conductivities of two hydrates with different guest molecules can provide new information about the mechanisms of phonon scattering in crystal hydrates.