Ripplocations in Layered Materials: Sublinear Scaling and Basal Climb

TL;DR

This paper investigates ripplocations in layered materials, revealing their energetic properties, structural scaling, and role in dislocation pile-ups, which explain phenomena like volumetric expansion in irradiated graphite.

Contribution

It provides analytical expressions for ripplocation scaling and demonstrates their dominance in dislocation pile-ups through simulations.

Findings

Ripplocations have sublinear energetic scaling.

Dislocation pile-ups favor ripplocation formation.

Large pile-ups cause delamination and expansion in graphite.

Abstract

The ripplocation is a crystallographic defect which is unique to layered materials, combining nanoscale delamination with the crystallographic slip of a basal dislocation. Here, we have studied basal dislocations and ripplocations, in single and multiple van der Waals layers, using analytical and computational techniques. Expressions for the energetic and structural scaling factors of surface ripplocations are derived, which are in close correspondence to the physics of a classical carpet ruck. Our simulations demonstrate that the lowest-energy structure of dislocation pile-ups in layered materials is the ripplocation, while large dislocation pile-ups in bulk graphite demonstrate multilayer delamination, curvature and voids. This can provide a concise explanation for the large volumetric expansion seen in irradiated graphite.