THERMODYNAMICS AND KINETICS FOR NUCLEATION OF DIAMOND IN THE CHEMICAL VAPOR-DEPOSITION PROCESS

Nucleation of a metastable phase focusing on diamond was studied, based on the classical nucleation theory. It was shown that when the specific surface energy multiplied by the molar volume to a power of two-thirds is larger for the stable allotrope than for the metastable one, the thermodynamic stability of two allotropes can be reversed below a certain size of the particle. The nucleation intensity ratio of the stable to the metastable phase is shown to be critically affected by the variation of the specific surface energy ratio of two phases. Within uncertainties of the surface energy data of diamond and graphite, the dominance of nucleation changes from graphite to diamond. Surface energy modification of diamond or graphite was suggested to be responsible for nucleation and growth of diamond in the CVD process. © 1992.