# Dislocation

In materials science, a dislocation is a crystallographic defect, or irregularity, within a crystal structure. The presence of dislocations strongly influences many of the properties of materials. The theory was originally developed by Vito Volterra in 1905 but the term 'dislocation' was not coined until later by the late Professor Sir Frederick Charles Frank of the Physics Department at the University of Bristol. Some types of dislocations can be visualized as being caused by the termination of a plane of atoms in the middle of a crystal. In such a case, the surrounding planes are not straight, but instead bend around the edge of the terminating plane so that the crystal structure is perfectly ordered on either side. The analogy with a stack of paper is apt: if a half a piece of paper is inserted in a stack of paper, the defect in the stack is only noticeable at the edge of the half sheet.

There are two primary types: edge dislocations and screw dislocations. Mixed dislocations are intermediate between these.

Mathematically, dislocations are a type of topological defect, sometimes called a soliton. The mathematical theory explains why dislocations behave as stable particles: they can be moved about, but maintain their identity as they move. Two dislocations of opposite orientation, when brought together, can cancel each other (this is the process of annihilation), but a single dislocation typically cannot "disappear" on its own.

Read more about Dislocation:  Dislocation Geometry, Observation of Dislocations, Sources of Dislocations, Dislocations, Slip and Plasticity, Dislocation Climb

### Other articles related to "dislocations, dislocation":

Lomer-Cottrell Junction
... junction is a particular configuration of dislocations ... When two perfect dislocations along a slip plane, each perfect dislocation can split into two Shockley partial dislocations a leading dislocation and a trailing dislocation ... When the two leading Shockley partials combine, they form a separate dislocation with a burgers vector that is not in the slip plane ...
Dislocation Climb
... Dislocations can slip in planes containing both the dislocation and the Burgers Vector ... For a screw dislocation, the dislocation and the Burgers vector are parallel, so the dislocation may slip in any plane containing the dislocation ... For an edge dislocation, the dislocation and the Burgers vector are perpendicular, so there is only one plane in which the dislocation can slip ...