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

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.