Thermal resistivity, heat capacity and phase diagram of CBr₄ under pressure

Abstract

We have measured simultaneously the thermal resistivity and the heat capacity per unit volume for phases I, II, III and IV of CBr₄. We have used the transient hot-wire method, and have made measurements over the ranges 170 K to 425 K, and up to 2 GPa. Our results, and other evidence, indicate that I and III are plastic crystal phases, and that there is a significant degree of structural disorder in phase II. Three-phonon interactions probably provide the dominant contribution to the thermal resistivity of phase IV. Using structural analogies with the phases of CCl₄, we find that the relative values of the thermal resistivities are roughly as predicted by simple theory.