An investigation was made, using Raman spectroscopy, of the effect of high pressures upon the annealing of the surface disorder that was introduced by H, C and Ni ion-implantation. In the case of H implantation, the resultant disorder decreased during annealing at 650C and 7.7GPa. After C implantation, defect annealing started at 500C and 7.7GPa. In the case of Ni implantation, it began at 850C for the same pressure. For these 3 cases, there was essentially no annealing effect for treatment in vacuum at up to 1100C. The results indicated that high pressures played an important role in defect annealing. It accelerated graphitization, and this was tentatively attributed to the large volume of the defective ion implanted phase. Although the high-pressure annealing occurred well within the thermodynamic stability region of diamond, the graphite phase was recovered. This indicated that the nucleation barrier for diamond was very high when compared with that for graphite.

High Pressure Annealing of Defects Induced by Ion Implantation on Graphite. S.R.S.Soares, N.M.Balzaretti, R.P.Livi, A.S.Pereira, J.A.H.Da Jornada: Nuclear Instruments and Methods in Physics Research B, 2001, 175-177[1-4], 474-8