Glide plane, diamond

Figure 4.2 Quasi-hexagonal dislocation loop lying on the (111) glide plane of the diamond crystal structure. The <110> Burgers vector is indicated. A segment, displaced by one atomic plane, with a pair of kinks, is shown a the right-hand screw orientation of the loop. As the kinks move apart along the screw dislocation, more of it moves to the right.

The glide planes on which dislocations move in the diamond and zincblende crystals are the octahedral (111) planes. The covalent bonds lie perpendicular to these planes. Therefore, the elastic shear stiffnesses of the covalent bonds... 

Figure 5.8 Projection of the diamond structure so the (111) glide planes (AB) are perpendicular to the plane of the figure. Then the covalent bonds connecting the atoms in planes (AB) and (A ) are perpendicular to the (111) planes.The glide plane spacing, a of the figure corresponds to the bond length AA. The Burgers displacement, b corresponds to the atomic spacing along A or A. ...

Finally, there is a rare type of glide called a diamond glide (plane or operation).-This can occur only for 1 or F lattices where a translation of, for example, a/4 + b/4 can move a corner lattice point to a face centering lattice point (or vice versa). The symbol for a diamond glide is d. 

Diamond glide plane (pair of planes in centred cells only) — 1/4 along line parallel to projection plane, combined with 1/4 normal to projection plane (arrow indicates direction parallel to the projection plane for which the normal component is positive) d... 

The d notation indicates a diamond glide plane, found in diamond or zinc blende extended crystal structures. Whereas ghde planes are found in many inorganic-based crystals, screw axes are found predominantly in protein structures. 

Glide Operation that is a product of a mirror and a translation that is a fraction of the lattice vector in the plane of the mirror. There are axial glides, double glides, diagonal glides, and diamond glides. 

Glide planes combine a reflection in a mirror plane with a shift parallel to this plane. They are called a, b, and c planes when the shift equals 1/2 of a cell edge (i.e. a/2, b/2, and c/2, respectively), n planes when it equals 1/2 of (any) face-diagonal or body-diagonal of the unit cell, and d (so-called diamond ) planes when it equals 1/4 of such diagonal. 

The diamond glide plane d has been left out for clarity. 

Fig. 2. The diamond structure viewed in projection along [11 0], The (111) glide plane is horizontal, and the two possible shear locations I (shuffle set) and II (ghde set) are indicated.

Sphalerite or zinc blende is the chief ore of ZnS. ZnS as well as many of the III-V and II-VI compound semiconductors such as GaAs form a diamond-like stmeture with one type of atom on the fee lattice sites and the other type of atom on every other tetrahedral site. The space group is F43wx (the d-glide plane symmetry in diamond is lost by the fact that different atoms occupy the interstitial sites). Since there are four atoms on the lattice points of the fee unit cell, the stoichiometry is maintained if half of the eight tetrahedral sites are occupied by the second atom. For these systems, the double stacking described above would have different atoms in doubled layers, i.e., A(Zn) A (S) B(Zn) B (S) C(Zn) C (S), etc. This type of structure is the same as shown in Figure 5.9 if the black spots are... 

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