Geometric structure (SWCNT) in the preparation of a carbon nanotube by twisting part of a graphene plate (square-rectangle representing a single non-tubular cell) and the vector Ch (nano-microelectronics)
Researcher and author: Dr. ( Afshin Rashid)
Note: Geometric structure (SWCNT) in the preparation of a carbon nanotube by twisting part of the graphene plate. (Square_rectangle represents a single non-tubular cell) denoted by the vector Ch.
SWCNTs nanotubes with the same properties can be obtained in two ways:
1_ Controlled synthesis. 2_ Chemical separation
After the type of synthesis that has been done in the two methods. Although efforts have been made to control the properties and quality of CNTs in the CVD process, none of these methods can produce a large number of identical SWCNTS and no single species can be created. At present, it seems that post-synthesis separation methods can be better commercialized than control methods during synthesis. Of course, it would be cheaper if isolation methods resulted in a large amount of single species production during synthesis. Isolation methods have used alternating current dielectrophoresis and electric current oxidation to enrich advanced or semiconductor metal nanotubes.
Structure and structure of nanotubes (SWCNTs) and CNTs
The structural differences between CNTs and CNTs can be thought of as graphite plates with a layered hexagonal lattice that are tubularly cylindrical. Nanotubes are characterized by the number of layers that their cylindrical walls form; Single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) and SWCNT are obtained from a graphene plate of a specified size. According to the cylindrical symmetry, based on the cylindrical shape (we can only pipe it in one direction so that 2 atoms are in line. To describe the structure of SWCNT, two parameters are used. One is Ch, which starts from the main atom The chiral vector is oriented toward the next atom, also called the tube vector, and its length is equivalent to the circumference of the nanotube circle. Chiral SWCNTs are optically active and can have two non-equivalent helical orientations. The piping process can be done both from above and below the graphene plate. The two tubes will be mirror images of each other, in which case the graphene plate is the mirror plate. These two states produce left-handed (M) and right-handed (P) isomers. In the case of chiral nanotubes, these plates are called reflection plates, and the two nanotubes are equivalent.
Conclusion :
It can be concluded that when (3 / mn) is an integer, SWCNT is a metal type and in other cases a semiconductor. This is entirely geometrical, with one-third of metal SWCNTs and two-thirds semiconductors. Single-walled nanotubes are exceptional compounds because they can be metallic or semiconductor, while there is no difference between them and the chemical bond between the carbon atoms inside the tubes, and no impurities or the presence of added foreign matter is observed.
Researcher and author: Dr. ( Afshin Rashid)
PhD in Nano-Microelectronics