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Stacking faults are two dimensional planar defects that can occur in crystalline materials. They can be formed during crystal growth, during plastic deformation as partial dislocations move as a result of dissociation of a perfect dislocation, or by condensation of point defects during high-rate plastic deformation. [3]
Electron microscopy of antisites (a, Mo substitutes for S) and vacancies (b, missing S atoms) in a monolayer of molybdenum disulfide.Scale bar: 1 nm. [1]A crystallographic defect is an interruption of the regular patterns of arrangement of atoms or molecules in crystalline solids.
These planar defects are similar to stacking faults in that they are often created through slip of atomic planes and dislocation motion, but the degree of translation varies. In stacking faults, the region of stacking mismatch is bounded by two partial dislocations, and an extended dislocation is formed.
A stacking fault is an irregularity in the planar stacking sequence of atoms in a crystal – in FCC metals the normal stacking sequence is ABCABC etc., but if a stacking fault is introduced it may introduce an irregularity such as ABCBCABC into the normal stacking sequence. These irregularities carry a certain energy which is called the ...
There are a wide variety of crystallographic defects. The hypothetical concept of a perfect crystal is important in the basic formulation of the third law of thermodynamics . In crystallography , the phrase 'perfect crystal' can be used to mean "no linear or planar imperfections", as it is difficult to measure small quantities of point ...
An edge dislocation is a defect where an extra half-plane of atoms is introduced midway through the crystal, distorting nearby planes of atoms. When enough force is applied from one side of the crystal structure, this extra plane passes through planes of atoms breaking and joining bonds with them until it reaches the grain boundary.
Some defects in the boundary, such as steps and ledges, may also offer alternative mechanisms for atomic transfer. Grain growth can be inhibited by second phase particles via Zener pinning . Since a high-angle boundary is imperfectly packed compared to the normal lattice it has some amount of free space or free volume where solute atoms may ...
The boundary between crystal segments is called a composition surface or, if it is planar, a composition plane. The composition plane is often, though not always, parallel to the twin law plane of a reflection law. If this is the case, the twin plane is always parallel to a possible crystal face. [2]