Crystallographic Shear

Surface defects are categorized in step edges, oxygen vacancies, line defects (closely related to the 1x2 reconstruction), common impurities, and the manifestation of crystallographic shear planes CSPs at surfaces.



...detailed experimental evidence about the microstructure of crystallographic shear structures (CS phases) becoming available. The relation between the concept of crystallographic shear and existing views of defects and non-stoicheiometry in inorganic compounds was studied. Most CS phases do not appear to contain point defects in significant concentrations- i.e. in sufficient number to contribute materially to the apparent composition ranges of CS compounds. In a heuristic sense, at least, the collapse of the parent crystal structure which produces a CS plane eliminates point defects; it is not implied that the presence of point defects in high concentration is a necessary precursor stage in the formation of a CS plane. The mechanism of this transformation process is still not clear, and the role of point defects in certain structural types, notably the ' block' structure oxides, has continued to excite interest.

http://www.rsc.org/ebooks/archive/free/BK9780851862705/BK9780851862705-00001.pdf

Wadsley defects and crystallographic shear in hexagonally close-packed structures
Authors; Andersson, Sten; Galy, Jean; Journal of Solid State Chemistry, Volume 1, Issue 3-4, p. 576-582.