Effect of hydrogen implantation on the graphite used in high pressure diamond synthesis

The objective of the present work is to investigate the effect of hydrogen implantation on graphite in the high pressure diamond synthesis. A comparis on of the graphite/diamond conversion for different fluences of hydrogen im plantation revealed that the diamond nucleation and the total mass yield ar e always higher (up to 46%) than in experiments without implantation. The m aximum nucleation for the studied cases occurred at a fluence of 1 x 10(17) hydrogen ions/cm(2). This behavior is not observed when other ions, such a s krypton and argon, are implanted on the graphite, or when hydrogen is pre sent in the reaction cell but not implanted on the graphite. The results we re interpreted as a consequence of the creation of additional tetrahedral s p(3) bonded carbon atoms when the graphite is hydrogen implanted, which wou ld act as effective diamond nucleation sites in the high pressure synthesis . (C) 2000 Elsevier Science S.A. All rights reserved.