Regulating Screw Dislocations in Diamond by Tailoring the Chiral Angle of Carbon Nanotube Precursors

Abstract

Diamond, the hardest natural material, is scarce and expensive to mine, motivating efforts to synthesize high-performance diamond. Dislocations are key microstructural features governing diamond’s mechanical properties, yet their design mechanisms remain unclear. In this work, our large-scale molecular dynamics (MD) simulations demonstrate that the density of screw dislocation in cubic diamond (CD) increases with the increase of chiral angle differences between adjacent graphene layers in multiwalled carbon nanotubes (MWCNTs) during the CNT–diamond phase transition. During the phase transition, larger initial chiral angle differences between adjacent graphene layers increase the zigzag-chain orientation mismatch so that in regions with closely spaced chain intersections the CNT transforms into diamond, whereas in regions with larger mismatch the CNT evolves into screw dislocations. This study reveals the dominant role of the CNT chiral angle in controlling screw dislocations and offers a theoretical framework for improving the performance of synthetic diamond.