Partial dislocation

Then, mark the center of the opposite faces for each point as α, β, γ, and δ, respectively.

Any combination of Roman letters describes a member of the {111} slip planes in an FCC crystal.

[2] It is necessary that the interior letters of a given operation match, but many can be added in sequence to describe more complex mechanisms.

This means that higher stacking fault energy materials, i.e. those with high shear modulus and large Burgers vectors, will have smaller distance between partial dislocations.

Conversely, low stacking fault energy materials will have large distances between partial dislocations.

[3][4] Conversely, high stacking fault energy materials will be easier to cross slip.

Thompson tetrahedron drawn inside an FCC crystal and then rotated to more easily see faces and vertices.
An unfolded Thompson Tetrahedron
Unfolded Thompson tetrahedrons contain information to quickly view Burgers vectors relative directions in an FCC structure.
Partial dislocations move freely, but in order to cross slip onto a different plane, they must first constrict to before slipping on a different plane.