Prismatic Edge Dislocations in Graphite

TL;DR

This study uses density functional theory to analyze prismatic edge dislocations in graphite, revealing their structures, energetics, stability at high temperatures, and implications for damage healing and energy storage.

Contribution

It provides the first detailed DFT-based analysis of prismatic dislocation cores in graphite, including their stability, mobility, and role in damage processes.

Findings

Prismatic dislocation cores are stable up to ~1500K in graphite.

Bonded and free-standing core structures have similar energies.

Dislocation mobility influences damage healing and energy storage.

Abstract

Dislocations are a central concept in materials science, which dictate the plastic deformation and damage evolution in materials. Layered materials such as graphite admit two general types of interlayer dislocations: basal and prismatic dislocations, of which prismatic dislocations have been relatively less studied. Using density functional theory (DFT) calculations, we have examined different prismatic core structures in graphite and evaluated their structure, energetics and mobility. We find close energetic interplay between bonded and "free-standing" core structures in both zigzag and armchair directions, with a reconstructed stable zigzag core identified. We explore grain boundaries and prismatic dislocation pile-up, identifying metastable structures which may be important in energy storage. The role of interlayer stacking in core structure, dislocation glide and climb is also considered in-depth. Our calculations suggest that the prismatic dislocation core is stable up to high temperatures of approximately 1500K in bulk graphite. Above this temperature, the breaking of bonds in the dislocation core can facilitate climb, grain-boundary motion, and the annealing of damage through prismatic dislocation glide.