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Line defects can be described by gauge theories. Dislocations are linear defects, around which the atoms of the crystal lattice are misaligned. [14] There are two basic types of dislocations, the edge dislocation and the screw dislocation. "Mixed" dislocations, combining aspects of both types, are also common. An edge dislocation is shown. The ...
In crystallography, a disclination is a line defect in which there is compensation of an angular gap. They were first discussed by Vito Volterra in 1907, [1] who provided an analysis of the elastic strains of a wedge disclination.
If the cut only goes part way through the crystal, and then slipped, the boundary of the cut is a screw dislocation. It comprises a structure in which a helical path is traced around the linear defect (dislocation line) by the atomic planes in the crystal lattice. In pure screw dislocations, the Burgers vector is parallel to the line direction ...
The existence of a topological defect can be demonstrated whenever the boundary conditions entail the existence of homotopically distinct solutions. Typically, this occurs because the boundary on which the conditions are specified has a non-trivial homotopy group which is preserved in differential equations; the solutions to the differential equations are then topologically distinct, and are ...
In crystallography, a vacancy is a type of point defect in a crystal where an atom is missing from one of the lattice sites. [2] Crystals inherently possess imperfections, sometimes referred to as crystallographic defects. Vacancies occur naturally in all crystalline materials.
Therefore, a perfect line dislocation in FCC has the burgers vector ½<110>, which is a translational vector. [4] Splitting into two partial dislocations is favorable because the energy of a line defect is proportional to the square of the burger’s vector magnitude.
This defect produces a characteristic absorption and luminescence line at 415 nm and thus does not induce color on its own. However, the N3 center is always accompanied by the N2 center, having an absorption line at 478 nm (and no luminescence). [29] As a result, diamonds rich in N3/N2 centers are yellow in color.
Slip bands form due to plastic deformation, and the analysis of the force on a dislocation considers the two-dimensional nature of the dislocation line defect. General definitions of the Peach– Koehler configurational force (𝑃 𝑘𝑗 ) [ 52 ] (or the elastic energy-momentum tensor [ 53 ] ) on a dislocation in the arbitrary 𝑥 1 , 𝑥 ...