Size-dependent nanodiamond-graphite phase transition at 8 GPa

The size-dependent diamond-graphite phase transition was detected in the course of a study of the growth of nanosized diamond particles under conditions of thermal treatment at 8 GPa. It was found that a critical size of diamond nanoparticles, on reaching which they transformed into graphite, was reached at 1623 K and a treatment time of 60 s, and it was equal to ~18 nm. The activation energy of the solid-phase growth of nanosized diamond particles at 8 GPa was determined to be 112±8 kJ/mol.