The effect of proton ordering on the thermal conductivity of clathrate tetrahydrofuran hydrate

The effect of proton ordering in tetrahydrofuran hydrate is detected using a technique based on measurement of thermal conductivity. The thermal conductivity of tetrahydrofuran hydrate is measured by the steady-state potentiometric method in the interval 2-150 K. Two regimes are selected to observe the effect: (i) slow cooling of the hydrate sample, and (ii) doping of the hydrate with a small quantity of KOH alkali to a concentration of 10(-4). Proton ordering affects the temperature dependence of the thermal conductivity, changing its glass-like behavior to crystal-like below 150 K. The phonon maximum that appears in the temperature dependence of the thermal conductivity at T= 17 K is attributed to the cooperative process of local proton ordering Stimulated by orientational and ionic defects. (c) 2008 American Institute of Physics.