(Rolled or  chiral  vector) of graphene layers in changing the electrical properties of nanotubes (Nano tube) PhD Nano _ Microelectronics 

Researcher  and author: Dr.   (   Afshin Rashid)


Note: Layers of  nanotubes   can behave like a metal and be electrically angled. Structure and structure changes in them can  display semiconductor properties. Or be non-conducting.  For example, a slight change in the helix can turn a pipe from a metal to a semiconductor with a large gap.

Carbon nanotubes are hollow cylinders composed of carbon atoms in a hexagonal structure. Two common zigzag and armature structures with various  geometric and behavioral characteristics are studied to evaluate the effect of structure type on changes in mechanical properties, the most important of which is the modulus of elasticity. These two widely used structures in the present study have been modeled by finite element method in Mark analyst software and the effect of changing the appearance of the carbon nanotube structure on its modulus of elasticity has been studied. The behavior of covalent bonds between carbon atoms is assumed by assuming bending elements with modulus of elasticity and a certain Poisson's ratio and applying a net tensile load to its upper surface to calculate the amount of modulus of elasticity of the structures under study. According to studies, the armature structure has a higher modulus of elasticity compared to zigzag specimens.

So that zigzag specimens always tend to increase their modulus of elasticity and reach the corresponding value corresponding to the ideal structure of the armature. The direction of rolling up (rolling or  chiral  vector) of graphene layers determines the change in electrical properties of nanotubes. Chirality describes the hexagonal lattice angle of a carbon nanotube. Nano seat tubes   - so-called because of the shape of the seat like their edges - have the same chiral indexes and are highly desirable for their complete guidance. They are not unlike  zigzag nanotubes   , which may be semiconductors. Converting a 30-degree graphene sheet changes the nanotube that changes from chair to chair or zigzag or vice versa.

While MWCNTs always reach and reach at least the same level of conductivity of metals, the conductivity of SWCNTs depends on their chiral vector. The properties of carbon nanotubes are not the same.At present, SWCNTs are prepared by various techniques such as arc discharge, hydrocarbon pyrolysis in the presence of catalyst, laser evaporation and chemical vapor deposition. , Spring-like and spiral. Existence of different structures expands the properties and applications of SWCNTs, but newly synthesized SWCNTs contain many different nanotubes, which is the main obstacle to their use in high-efficiency nano-equipment. It has been shown that the physical and electronic properties of a SWNT depend on the diameter of the tube and its structure (m, n). In most applications, we need nanotubes with the same properties. Example The performance of a CNT-based nanoelectronic device is significantly improved by using the same nanotubes. Field effect transistors with on / off ratios of 106, using carbon nanotubes enriched with (5,


Conclusion:
Modification of structure and evolution and change of chiral angle of monolayer and multilayer) CNT and CNTs carbon nanotubes are   widely used in energy storage, nanocomposite materials, nanoelectronics and nanosensors, which result in (layer change and chiral angle refraction) the creation of these properties. Due to their large surface area, hollow structure, high mechanical strength, excellent electrical properties and unique electronic bond structures. 

Researcher  and author: Dr.   (   Afshin Rashid)

PhD in Nano-Microelectronics