Isochoric thermal conductivity of solid freons CF2CI2 and CHF2CI of methane series
Abstract
The isochoric thermal conductivity and thermal pressure of solid freons CF2Cl2 and CHF2Cl of the methane series are studied at premelting temperatures. It is found that the thermal conductivity of CHF2Cl increases weakly with temperature, while for CF2Cl2 it remains practically constant. These parameters are compared with those for other freons of the methane series. The relation between the temperature dependence of thermal conductivity and the orientational motion of molecules is considered. It is shown that the behavior of isochoric thermal conductivity in orientationally ordered phases is in the best agreement with the case of strong scattering and the concept of thermal conductivity “minimum.” An increase in thermal conductivity with temperature in orientationally disordered phases is associated with suppression of phonon scattering at rotational excitations due to a decrease in correlations in the rotation of neighboring molecules.