Search results
Results from the WOW.Com Content Network
Comparison of fcc and hcp lattices, explaining the formation of stacking faults in close-packed crystals. In crystallography, a stacking fault is a planar defect that can occur in crystalline materials. [1] [2] Crystalline materials form repeating patterns of layers of atoms. Errors can occur in the sequence of these layers and are known as ...
They are formed by a local deviation of the stacking sequence of layers in a crystal. An example would be the ABABCABAB stacking sequence. A twin boundary is a defect that introduces a plane of mirror symmetry in the ordering of a crystal. For example, in cubic close-packed crystals, the stacking sequence of a twin boundary would be ABCABCBACBA.
The intuitive meaning of a stack is that it is a fibred category such that "all possible gluings work". The specification of gluings requires a definition of coverings with regard to which the gluings can be considered. It turns out that the general language for describing these coverings is that of a Grothendieck topology.
The stacking-fault energy (SFE) is a materials property on a very small scale. It is noted as γ SFE in units of energy per area. A stacking fault is an interruption of the normal stacking sequence of atomic planes in a close-packed crystal structure. These interruptions carry a certain stacking-fault energy.
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.
The Scherrer equation, in X-ray diffraction and crystallography, is a formula that relates the size of sub-micrometre crystallites in a solid to the broadening of a peak in a diffraction pattern.
Extrinsic and intrinsic defects can interact producing new defect complexes. Such interaction usually occurs if a diamond containing extrinsic defects (impurities) is either plastically deformed or is irradiated and annealed. Schematic of the H3 and H2 centers. Most important is the interaction of vacancies and interstitials with nitrogen.
The block-stacking problem is the following puzzle: Place identical rigid rectangular blocks in a stable stack on a table edge in such a way as to maximize the overhang. Paterson et al. (2007) provide a long list of references on this problem going back to mechanics texts from the middle of the 19th century.