Reaction of rhenium and carbon at high pressures and temperatures

A study of the reaction of rhenium with carbon at high-(P, T) conditions up to P max = 67 GPa and T max = 3800 K is presented. A hexagonal ReC x was identified as the stable phase at high-(P, T) conditions. A composition of ReC0.5 is proposed. No evidence for a cubic ReC polymorph with rocksalt structure, as suggested in the literature, or for any other phase was found at the P-T conditions explored. A preliminary P-T rhenium-carbon phase diagram has been derived and properties such as bulk moduli and elastic stiffness coefficients were obtained.