THERMAL-CONDUCTIVITY OF A CLATHRATE WITH RESTRAINED GUESTS - THE CCL4CLATHRATE OF DIANINS COMPOUND

The thermal conductivity of the CCl4 clathrate of ihydro-2,2,4-trimeth yl-2H-1-benzopyran-4-yl)phenol (Dianin's compound) has been measured u sing the steady-state potentiometric method. The temperature profile o f the thermal conductivity coefficient of this crystalline material ha s glasslike character. The highly effective thermal resistance mechani sm is ascribed to the scattering of acoustic phonons off localized low -frequency vibrations of the molecular moieties. The role and the beha vior of the guest molecules in thermal conductivity are discussed in t he wider context of the thermal properties of this material. The data presented complement the previous measurement on the clathrand and the ethanol clathrate of Dianin's compound. In contrast with the latter, guest molecules in the CCl4 clathrate play a minor role in the thermal conductivity, as it is found to be much the same as the empty host la ttice. The experimental results are interpreted on the premise of the resonant scattering model, with particular emphasis on the importance of the dynamics of the guest molecules to thermal resistance.