Stone Wales defect
Encyclopedia
A Stone–Wales defect is a crystallographic defect
that occurs on carbon nanotube
s and graphene
and is thought to have important implications for nanotube's mechanical properties. The defect is named after Anthony Stone
and David Wales of Cambridge University
, who described it in a 1986 paper on the isomerization of fullerenes. However, a rather similar defect was described much earlier by Peter Thrower
in a paper on defects in graphite
. For this reason the term Stone–Thrower–Wales defect is sometimes used. The defect is thought to be responsible for nanoscale plasticity
and the brittle-ductile transitions
in carbon nanotubes.
The Stone–Wales, or "pyracylene", transformation is the 90° rotation of two carbon
atom
s with respect to the midpoint of the bond. The Stone–Wales transformation is also used to describe the structural changes of sp²-bonded carbon nanosystems. For example, it has been proposed that the coalescence
process of fullerenes or carbon nanotubes may occur through a sequence of such a rearrangement. By the Stone–Wales transformation, four hexagons are changed into two pentagons and two heptagons.
Crystallographic defect
Crystalline solids exhibit a periodic crystal structure. The positions of atoms or molecules occur on repeating fixed distances, determined by the unit cell parameters. However, the arrangement of atom or molecules in most crystalline materials is not perfect...
that occurs on carbon nanotube
Carbon nanotube
Carbon nanotubes are allotropes of carbon with a cylindrical nanostructure. Nanotubes have been constructed with length-to-diameter ratio of up to 132,000,000:1, significantly larger than for any other material...
s and graphene
Graphene
Graphene is an allotrope of carbon, whose structure is one-atom-thick planar sheets of sp2-bonded carbon atoms that are densely packed in a honeycomb crystal lattice. The term graphene was coined as a combination of graphite and the suffix -ene by Hanns-Peter Boehm, who described single-layer...
and is thought to have important implications for nanotube's mechanical properties. The defect is named after Anthony Stone
Anthony Stone
Anthony Stone is a British theoretical chemist. He studied natural sciences at Emmanuel College, Cambridge and obtained a Ph.D. in theoretical chemistry under H. Christopher Longuet-Higgins. In 1964 he took up a position in the Department of Chemistry at the University of Cambridge, where he...
and David Wales of Cambridge University
University of Cambridge
The University of Cambridge is a public research university located in Cambridge, United Kingdom. It is the second-oldest university in both the United Kingdom and the English-speaking world , and the seventh-oldest globally...
, who described it in a 1986 paper on the isomerization of fullerenes. However, a rather similar defect was described much earlier by Peter Thrower
Peter Thrower
Peter Thrower is a professor emeritus of materials science and engineering at Pennsylvania State University, and is editor-in-chief of the journal Carbon, a post he has held since 1982. He also edited the review journal Chemistry and Physics of Carbon from 1973 to 1998...
in a paper on defects in graphite
Graphite
The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient Greek γράφω , "to draw/write", for its use in pencils, where it is commonly called lead . Unlike diamond , graphite is an electrical conductor, a semimetal...
. For this reason the term Stone–Thrower–Wales defect is sometimes used. The defect is thought to be responsible for nanoscale plasticity
Plasticity (physics)
In physics and materials science, plasticity describes the deformation of a material undergoing non-reversible changes of shape in response to applied forces. For example, a solid piece of metal being bent or pounded into a new shape displays plasticity as permanent changes occur within the...
and the brittle-ductile transitions
Ductility
In materials science, ductility is a solid material's ability to deform under tensile stress; this is often characterized by the material's ability to be stretched into a wire. Malleability, a similar property, is a material's ability to deform under compressive stress; this is often characterized...
in carbon nanotubes.
The Stone–Wales, or "pyracylene", transformation is the 90° rotation of two carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
atom
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
s with respect to the midpoint of the bond. The Stone–Wales transformation is also used to describe the structural changes of sp²-bonded carbon nanosystems. For example, it has been proposed that the coalescence
Coalescence (chemistry)
In chemistry, coalescence is a process in which two phase domains of the same composition come together and form a larger phase domain.-References:*...
process of fullerenes or carbon nanotubes may occur through a sequence of such a rearrangement. By the Stone–Wales transformation, four hexagons are changed into two pentagons and two heptagons.