Heat transfer in the orientationally disordered phase of SF6

The isobaric thermal conductivity of solid SF6 is investigated in the high-temperature phase. The experimental results are rescaled to a constant density. The isochoric thermal conductivity initially decreases with increasing temperature, then passes through a smooth minimum and begins to grow. A modified version of the reduced coordinate method is used to calculate the phonon–phonon and phonon–rotational contributions to the total thermal resistance. The growth of the isochoric thermal conductivity is explained by a weakening of the scattering of phonons on collective rotational excitations of the molecules as the correlations of the rotation weaken.