SiC enhanced nucleation of diamond under high pressure and high temperature

Abstract

Three kinds of catalyst have been prepared to investigate the role of SIC in diamond nucleation under high pressure and high temperature: (1) a fresh Ni-SiC powder mixture; (2) a heat-treated Ni-SiC mixture at 1300 degrees C for 2 h in vacuum, and (3) a heat-treated Ni-Si mixture at 1100 degrees C for 3 h in vacuum. When carbon black was treated with each catalyst at 4.7 GPa, 1450 degrees C for 5 min, diamond was synthesized only in the specimen containing the fresh mixture of Ni-SiC catalyst. The added fresh SiC enhanced drastically diamond formation. SiC thus appears to act as direct nucleation sites of diamond under the experimental condition.