A Revisited Mechanism of the Graphite-to-Diamond Transition at High Temperature
The graphite-diamond transition, under high-pressure and high-temperature conditions, has been a central subject in physical science. However, its atomistic mechanism remains under debate. Employing large-scale molecular dynamics (MD) simulations, we report a mechanism whereby the diamond nuclei in the graphite matrix propagate in two preferred directions, among which the graphite  is about 2.5 times faster than . Consequently, cubic diamond (CD) is the kinetically favorable product, while only a few hexagonal diamonds (HDs) can exist as the twins of CDs. The coherent interface of t-(100)gr//(11-1)cd + gr//[1-10]cd observed in MD simulation was confirmed by our high-resolution transmission electron microscopy experiment. The proposed mechanism not only clarifies the role of HD in graphite-diamond transition but also yields atomistic insight into strengthening synthetic diamond via microstructure engineering.
Phase transition; Molecular dynamics simulation; Superhard materials; Crystal growth; Interfaces
Condensed Matter Physics
Oganov, A. R.,
A Revisited Mechanism of the Graphite-to-Diamond Transition at High Temperature.