The Geometric Characterization of Dislocations

This circuit closes perfectly on itself (see Fig. 3.30a). In a chosen region of the crystal, a loop is made by a stepwise procedure, moving from one atomic position to the next, starting at some point, S. The conventional direction is clockwise and, while performing this procedure, the number of lattice steps in each direction is 

A dislocation can change from an edge orientation to a screw one. In real crystals, a dislocation is seldom pure edge or pure screw. Furthermore, dislocations are rarely found only in one plane. In general, dislocations are curved or form a loop. 

for three dislocations, or rather for a dislocation that branches into two other dislocations (not all dislocation lines leave the node), one may write  

one can sum up this section by stating that the most important feature of a dislocation is its Burgers vector. 

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