Abstract
Understanding the direct transformation from graphite to diamond has been a long-standing challenge with great scientific and practical importance. Previously proposed transformation mechanisms1-3, based on traditional experimental observations that lacked atomistic resolution, cannot account for the complex nanostructures occurring at graphite-diamond interfaces during the transformation4,5. Here, we report the identification of coherent graphite-diamond interfaces constituted with four structural motifs in partially transformed graphite samples recovered from static compression, using high-angle annular dark-field scanning transmission electron microscope. These observations provide vital insight into possible pathways of the transformation. Theoretical calculations confirm that transformation through these coherent interfaces is energetically favored to those through other paths previously proposed1-3. The graphite-to-diamond transformation is governed by the formation of nanoscale coherent interfaces (diamond nucleation), which, under static compression, advance to consume the remaining graphite (diamond growth). These results also shed light on transformation mechanisms of other carbon materials and boron nitride under different synthetic conditions.
Coherent interfaces with mixed hybridization govern direct transformation from graphite to diamond