Cubic packing, faults

Stacking faults. If, for example, we have a crystal structure based on cubic close packing, the sequence ABCABCABC... of layers may contain... 

Figure 6. TEM images of STAC-1 viewed down the a axis of a hexagonal unit cell (indicated by [M/]h) or the [110] direction of a cubic unit cell (indicated by [M/]c). The crystal is dominated by ABCABC close packing (indicated on (a)) with one stacking fault (marked by a horizontal line). A Fourier transform optical diffraction pattern with both Miller-Bravais indices to the hexagonal unit cell and Miller indices (in parentheses) to the cubic unit cell is inserted in (b). Simulated images based on a proposed model (right) are also inserted with specimen thickness of 30 nm, and lens focuses of—30 nm (a) and —10 nm (b).

Thus, the stacking fault patterns noted are a function of the t5q>e of lattice involved, not on the chemical composition of the material. For the most part, these stacking faults are found only in the high symmetry lattices such as hexagonal close-packed and cubic close-packed structures. 

An antiphase boundary (APB) is a type of stacking fault. Stacking faults also occur in materials that do not order, the simplest example being a fault in the normal close-packed layering in face-centered cubic metals, like copper, represented by CABCAB ABCABC. Stacking faults, formed during crystal growth or as a result of deformation (shp), are bounded by partial dislocations. 

Colloidal crystals can have a large variety of structures that depend on the nature of the colloids (hard sphere, charged, mixed sizes, and charges) [23]. The equilibrium crystalline phase of single-sized hard spheres has the face-centered cubic structure. Its energy is only about 10 k T lower than that of the hexagonal close-packed crystal [24]. Equivalently, the stacking faults on the close-packed planes in both... 

Fig. 3. Reconstructed confocal images of colloidal close-packed crystals. (A) Face-centered cubic crystal grown by sedimentation onto a (100) template. (B) Single crystal with stacking faults (between the gray spheres). (C) Just the gray spheres from part B the stacking faults extend through the volume (from Schall et al. [27]). (D) Three consecutive, somewhat defective hexagonal close-packed layers in a small crystal nucleated from the liquid (from...

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