Nucleation, graphite

Research has demonstrated that some calcium addition is required for proper graphite nucleation (24), This effect was observed even if cerium was added during the treatment process. 

Thus, there exists a narrow range of conditions, such as pressure (supersaturation), temperature, and composition as well as substrate sur ce state (structure, roughness, etc.), under which the nucleation and growth of diamond are significant and graphite is etched. In this competition, graphite nucleation and growth will essentially cease or will be covered by diamond,... 

In practice, it is found that the presence of sulphur in the atmosphere in the form of H2S effectively suppresses metal dusting. This is thought " to result from the suppression of graphite nucleation by the sulphur, which thereby halts the chain of dusting reactions. 

The possible success of a synthesis route using nongraphitic carbon would seem to depend upon the suppression of graphite nucleation and purity factors, since growth of high quality diamond requires low levels of impurities. This is more difficult to achieve in a carbon which has not been graphitized. 

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