Synthesize of Needlie-like Diamond Under High-temperature and Highpressure Using Nanometric-graphite as Carbon Source

Using nanometric\|graphite as carbon source and Fe 55 Ni 29 Co 16 powder as catalyst, the needle\|like diamond of 15μm in size can be synthesized under high\|temperature and high\|pressure of 1350K and 5 1GPa. However, the needle\|like diamond is seldom seen in the experiments of diamond synthesis. Under the same condition, cloosing Ni 70 Mn 25 Co 5 powder catalyst and sample assembly, the granular diamond of 5～20μm in size can be synthesized. These two sorts of diamond are transparent. The cause of the formation of needle\|like diamond is discussed in this paper. This phenomenon shows that the nanometric\|graphite particles can be used to synthesize diamond under lower temperature because of the surface activity of nanometric particles and nanometric scale.