Growth of nanomaterials by screw dislocation

Abstract

Controlling the morphology of nanomaterials is important for their fundamental study and practical application. Especially one-dimensional nanowires, nanorods, and nanotubes and two-dimensional nanoplates possess interesting physical and chemical properties due to their structural anisotropy. The key to obtaining these morphologies is to break the symmetry of crystal growth to promote anisotropic growth. In this chapter we discuss the catalyst-and template-free screw-dislocation-driven nanomaterial growth mechanism, in which an axial screw dislocation creates self-perpetuating growth steps upon intersecting with the crystal surface and enables anisotropic crystal growth under low supersaturation conditions. The presence of screw dislocations not only alters the growth kinetics of nanomaterials, but also distorts the crystal lattice and generates a strain field, both of which lead to morphology variation of the nanomaterials. The structural characteristics associated with dislocation-driven growth can be readily detected using transmission electron microscopy techniques. A review is presented on a wide range of nanomaterials formed under various conditions whose growth has been confirmed to be driven by screw dislocations, demonstrating the generality of this mechanism. A framework for rationally synthesizing anisotropic nanomaterials via dislocation-driven growth is provided. This will enable large-scale, low-cost production of nanomaterials for various applications.