Editing Crystallographic defect (section)

==Planar defects==<!-- This section is linked from [[Semiconductor]] -->

[[File:Schema fcc hcp.png|thumbnail|Origin of stacking faults: Different stacking sequences of close-packed crystals]]

*[[Grain boundary|Grain boundaries]] occur where the crystallographic direction of the lattice abruptly changes. This usually occurs when two crystals begin growing separately and then meet.
*[[Anti-phase domain|Antiphase boundaries]] occur in ordered alloys: in this case, the crystallographic direction remains the same, but each side of the boundary has an opposite phase: For example, if the ordering is usually ABABABAB ([[hexagonal close-packed]] crystal), an antiphase boundary takes the form of ABABBABA.
*[[Stacking fault]]s occur in a number of crystal structures, but the common example is in [[Close-packing|close-packed]] structures. 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.
*On planes of  [[single crystal]]s, steps between atomically flat terraces can also be regarded as planar defects. It has been shown that such defects and their geometry have significant influence on the adsorption of organic molecules<ref>{{cite journal|doi=10.1039/C2CP40800G |pmid=22751288 |title=The role of surface defects in large organic molecule adsorption: substrate configuration effects |year=2012|last1=Waldmann|first1=T.|journal=Physical Chemistry Chemical Physics|volume=14|issue=30 |pages=10726–31|bibcode = 2012PCCP...1410726W }}
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