Imperfect Oriented Attachment: Dislocation Generation in Defect-Free Nanocrystals

TLDR

Dislocations are common defects, yet crystals originate as dislocation‑free nuclei, and the mechanisms by which they form during early growth remain poorly understood. When nanocrystals grow by oriented attachment at specific surfaces with a small misorientation, dislocations arise, and spiral growth at closely spaced screw dislocations can produce complex polytypic and polymorphic structures. These observations are fundamentally important for understanding crystal growth.

Abstract

Dislocations are common defects in solids, yet all crystals begin as dislocation-free nuclei. The mechanisms by which dislocations form during early growth are poorly understood. When nanocrystalline materials grow by oriented attachment at crystallographically specific surfaces and there is a small misorientation at the interface, dislocations result. Spiral growth at two or more closely spaced screw dislocations provides a mechanism for generating complex polytypic and polymorphic structures. These results are of fundamental importance to understanding crystal growth.