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The defect is named after Anthony Stone and David J. Wales at the University of Cambridge, who described it in a 1986 paper [5] on the isomerization of fullerenes.However, a similar defect was described much earlier by G. J. Dienes in 1952 in a paper on diffusion mechanisms in graphite [6] and later in 1969 in a paper on defects in graphite by Peter Thrower. [7]
An example is the Stone Wales defect in nanotubes, which consists of two adjacent 5-membered and two 7-membered atom rings. Schematic illustration of defects in a compound solid, using GaAs as an example. Amorphous solids may contain defects. These are naturally somewhat hard to define, but sometimes their nature can be quite easily understood.
Crystals inherently possess imperfections, sometimes referred to as crystallographic defects. Vacancies occur naturally in all crystalline materials. At any given temperature, up to the melting point of the material, there is an equilibrium concentration (ratio of vacant lattice sites to those containing atoms). [ 2 ]
Stone–Wales defect; T. T centre; V. Vacancy defect; W. Wigner effect This page was last edited on 7 December 2023, at 23:08 (UTC). Text is available under the ...
Defects can occur in the form of atomic vacancies. High levels of such defects can lower the tensile strength by up to 85%. An important example is the Stone–Wales defect, otherwise known as the 5-7-7-5 defect because it creates a pentagon and heptagon pair by rearrangement of the bonds. Because of the very small structure of CNTs, the ...
An important application of mosaic crystals is in monochromators for x-ray and neutron radiation. The mosaicity enhances the reflected flux, and allows for some phase-space transformation. Pyrolitic graphite (PG) can be produced in form of mosaic crystals (HOPG: highly ordered PG) with controlled mosaicity of up to a few degrees.
Stonehenge's Altar Stone, weighing roughly six tons, was brought to the site from Scotland and not Wales, as was previously thought, researchers said.
In addition, physical properties are often controlled by crystalline defects. The understanding of crystal structures is an important prerequisite for understanding crystallographic defects. Most materials do not occur as a single crystal, but are poly-crystalline in nature (they exist as an aggregate of small crystals with different orientations).