Diamond Synthesis with Non-conventional Catalyst-solvents

Abstract

THE conventional catalyst-solvents used in the high-pressure, high-temperature synthesis of diamonds from graphite are the group VIII metals, Cr, Mn, Ta, and their alloys^1,2. A number of other substances have been claimed to act as catalyst-solvents for the graphite-to-diamond reaction, but at the extremely high pressures and high temperatures involved, contamination by the known group VIII catalysts used in the construction of the high-pressure cells may have promoted the diamond-forming reaction. It has been demonstrated experimentally that at sufficiently high static pressures and temperatures graphite will transform spontaneously to diamond^3–6 but the pressures and temperatures are about twice those required for the reactions aided by the conventional catalyst-solvents. Thus substances which may be sub-marginal as catalyst-solvents at the usual diamond synthesis pressures and temperatures might become fairly effective at higher pressures and temperatures^7,8.