Screw & edge dislocations in simple cubic crystal

Atomic structures of screw and edge dislocations in a simple cubic crystal lattice. Dislocations are line defects in crystals which are fundamental to explaining the mechanical properties of metals and ceramics. They can be thought of as lines of discontinuity running through the lattice, along with a vector describing the “break” in lattice known as the Burgers vector. Two extreme cases are shown here: the edge dislocation, in which the Burgers vector lies perpendicular to the dislocation line; and the screw dislocation, in which the Burgers vector lies parallel to the dislocation line.

In a simple cubic crystal, the edge dislocation can be thought of as a “missing" half-plane of atoms, but the screw dislocation is much harder to visualize. These models illustrate both types of defect, and have an accurate strain field around dislocation core (calculated from continuum mechanics). When printed with translucent filaments (recommended) they can be used to see into the core of the dislocation to aid visualization.