Structure and electronic properties of carbon nanotubes the. Wondrous world of carbon nanotubes internet reference, m. Introduction to carbon nanotubes carbon nanotubes were discovered in 1991 by sumio iijima of nec and are effectively long, thin cylinders of graphite, which you will be familiar with as the material in a pencil or as the basis of some lubricants. Review article carbon nanotubes and its applications.
The high temperature routes, such as the electricarc discharge technique. Structureassigned optical spectra of singlewalled carbon. Pdf geometric and electronic structure of carbon nanotube. Jan 18, 2018 carbon nanotubes, first discovered in download pdf opens in a new we present an overview of atomic and geometric structures of carbon nanotubes and their carbon nanotubes for data processing reza m. Each carbon atom z6 is covalently bonded to three neighbor carbons via sp2 molecular orbitals.
It is possible nowadays to study the structural and electronic properties of nanostructures in general, and carbon nanotubes in particular as well as the energetics of manyelectron systems by performing fully ab initio computations the first theoretical calculation of swcnts electronic structure was carried out using zone folding scheme 18,19. First, the unique relationship between swnt atomic structure and electronic properties, and the richness of structures observed in both purified and chemically etched nanotube samples are discussed. Carbon nanotubes can behave as thick lattice shells, when their atomic structure is characterized by the relatively large thickness, h nt, as compared to their radius, r nt. These cylindrical carbon molecules have novel properties that make them potentially useful in many applications in nanotechnology. Jan 01, 2012 cylindrical fullerenes are called carbon nanotubes or buckytubes. Electricalpropertiesandapplications ofcarbonnanotubestructures. Pdf ab initio study of the electronic structure of. Normally, carbon nanotubes consist of hollow carbon hexagonal networks concentrically arranged around one another, and terminated by end caps in which the surface meet under speci. The structure of an ideal infinitely long singlewalled carbon nanotube is that of a regular hexagonal lattice drawn on an infinite cylindrical surface, whose vertices are the positions of the carbon atoms. We discuss the oxidation of carbon nanotubes and how it is affected by structure and geometry. Pdf structure and dispersion of carbon nanotubes dale. Graphite is made up of layers of carbon atoms arranged in a hexagonal lattice, like chicken wire see. Electronic structure the electronic band structure of a nanotube can be described by considering the bonding of the carbon atoms arranged in a hexagonal lattice. The structure of carbon nanotubes can be examined in terms of three primary variables.
The topological structure of swnt is quite like modified single sheet graphene, thus the tubes are usually labeled in terms of the graphene lattice vectors. Determination of the chiral indices n,m of carbon nanotubes. Generally, synthesis methods of carbon nanotubes can be classified into two main categories corresponding to different temperatures. Since then, carbon nanotubes with various structures have been discovered. Oct 20, 2016 electrical properties the structure of a carbon nanotube determines how conductive the nanotube is. Electronic structure of carbon nanotubes zallowed states condense into lines there are qy3 lines on either side of the center of the brillouin zone zin case of 3,3 tube and all other armchair tubes, the allowed states lines include the k points of brillouin zone of graphene, hence all armchair tubes show a metallic behavior. Carbon nanotubes cnts are allotropes of carbon with a nanostructure that can have a lengthtodiameter ratio greater than 1,000,000. Pdf effect of electron irradiation on structure of carbon. Examples of swcnts whose structure includes various heterocycle. Although it is not physically accurate, these cylinders can best be visualized by imagining a sheet of graphite that has been rolled into a tube.
In addition, we present results on the electron field emission properties of macroscopic cnt cathodes. Effect of thermal treatment on the structure of multi. While graphite is known to oxidize primarily at defects to create etch pits, nanotubes have. Single walled carbon nanotubes can be formed by folding the sheet along lattice vectors. The cylindrical carbon molecules feature high aspect ratios lengthtodiameter values typically above 10 3, with diameters from about 1 nanometer up to tens of nanometers and lengths up to millimeters. The carbon nanotubes reported by iijima were mwnts synthesized by arc discharge methods. They can be singlewalled swcnt or multiwalled mwcnt, consisting of several concentrically interlinked nanotubes. Carbon is one of the most abundant and most fascinating elements on earth. Pdf atomic structure and electronic properties of single. The length scales of the atomic structure of such thick swcnt shells and thick mwcnt shells have to satisfy the criterion 4. Carbon nanotubes, science and technology part i structure. Based on highresolution transmission electron microscopy hrtem. Saito et al, imperial college press 1998 isbn 1860940935. The atomic structure of the cnt sidewalls resembles a foldedup.
Within the layers the atoms are arranged at the corners of hexagons which fill the whole plane. The atomic structure of a singlewalled carbon nanotube is well described by its chiral indices n,m that. Single layer of carbon atoms with each atom bound to three neighbours in a honeycomb structure note. Controlling the structure and properties of carbon nanotubes.
There are two different types of carbon nanotubes that exist by depending on the graphene sheet of the tubes that whether it is made by using many graphene sheets or a single graphene sheet. Growing zigzag 16,0 carbon nanotubes with structure. Carbon nanotubes and related structures the term nanotube is normally used to refer to the carbon nanotube, which has received enormous attention from researchers over the last few years and promises, along with close relatives such as the nanohorn, a host of interesting applications. Pdf the carbon nanotube cnt represents one of the most unique structure and the related mechanical, electronic and chemical properties. Growing zigzag 16,0 carbon nanotubes with structuredefined. The growth of zigzag singlewalled carbon nanotubes swnts is most challenging among all types of swnts, with the highest reported selectivity of. Carbon nanotubes cnts are nanostructures derived from rolled graphene planes and possess various interesting chemical and physical properties.
This unique onedimensional structure and concomitant properties endow carbon nanotubes with special. They can be thought of as a sheet of graphite a hexagonal lattice of carbon. Carbon nanotubes cnts are cylindrical molecules that consist of rolledup sheets of singlelayer carbon atoms graphene. Structure and electronic properties of carbon nanotubes. Pdf modifying the electronic structure of semiconducting. In order to visualize how nanotubes are built up, we start with graphite, which is the most stable form of crystalline carbon. For example, the quantized electron wavestates in a nanostructure are reflected in measurements of electron transport through the structure. In nanoscale sensor applications, particular atomic lattice structures of carbon nanotubes are selected in order to ensure desired electrical conductivity. A detailed raman spectroscopic study of asproduced nanotubes has also been conducted. The fourth valence electron, in thepz pz orbitals to form a.
Carbon nanotubes play a fundamental role in the rapidly developing field of nanoscience and nanotechnology because of their unique properties and high potential for applications. The individual nanoscale tubules of carbon have exceptional mechanical strength, high youngs modulus, 3 and. Another approach for the production of sts would be to grow swnts inside templates with the supernanotube structure, similar to the growth of 0. The strong bonds between carbon atoms also allow carbon nanotubes to withstand higher. This video describes carbon allotropes and carbon nanotubes. Morphological and structural types of carbon nanotubes. We then performed spectroscopic measurements using a commercial spectrofluorometer a jy. Complex structure of carbon nanotubes and their implications. To understand the structure of a carbon nanotube it can be first imagined as a rolled up sheet of graphene see figure 1.
The features of the carbon nanotubes are synthesized by cvd method based on the conditions of the work like temperature, pressure of operation, concentration and volume of hydrocarbon, also. Scanning tunneling microscopy, spectroscopy, and tightbinding calculations have been used to elucidate the unique structural and electronic properties of singlewalled carbon nanotubes swnts. Carbon nanotube, also called buckytube, nanoscale hollow tubes composed of carbon atoms. Therefore, the controlled preparation of chemically and structurally pristine swnts is a crucial issue for their advanced applications e. This oneatom thick layer of carbon is called graphene, and it is wrapped. It features research at the university of western australia into the use of carbon nanotubes in. The morphology of a carbon nanotube describes its general structure, including the number of walls swnt or mwnt, as well as its shape linearity, radius of curvature, etc. Its atomic lattice is composed of carbon atoms in the periodic hexagonal arrangement in the armchair configuration, which ensures. Nanotubes are the members of the fullerene structural family. The arc discharge evaporation method initially used to synthesize nanotubes has given way to large scale production by chemical vapor deposition 2. These are large macromolecules that are unique for their size, shape, and remarkable physical properties. However carbon nanotubes have been constructed with length to diameter ratio of up to 2,000,000.
The electronic band pstructure of graphene and carbon nanotubes. Harris, cambridge university press 1999 isbn 0521554462 physical properties of carbon nanotubes, r. This chapter deals with carbon nanotubes cns, which are not the only one structure of that geometry. Carbon nanotubes carbon nanotubes, long, thin cylinders of carbon, were discovered in 1991 by sumio iijima. Carbon nanotubes with different structure and morphology can now be produced in laboratory corresponding author. It presents a brief perspective of simple carbon structures. Multiwall nanotubes are found in the negative electrode deposit formed in the process of arc evaporation of graphite. Carbon nanotubes have two types of bonds due to 2sp hybridization. Pdf electronic band structure of isolated and bundled. The structures of helical carbon nanotubes have been studied by selected area electron diffraction saed methods in parallel with high resolution transmission electron microscopy.
You may have heard a lot about carbon nanotubes and their promising potentials by mean of these nanscale hollow atomic tubes. Another characteristic signature of a 1d system is the divergent van hove singular. Dec 20, 2002 the values ofe 11 and e 22 will vary with tube structure. Effect of thermal treatment on the structure of multiwalled. Carbon nanotubes transparent conductive materials wiley. At that time, the idea of testing such predictions seemed fanciful imaging these wires required the highest resolution. In this paper the hipco single wall carbon nanotubes swnt dispersed in a polyacrylonitrile matrix are used to demonstrate the validity of the scf concept. Rad umbc based on pages 473497 of nanoelectronics and electronic structure of carbon nanotubes. They can be singlewalled swcnt with a diameter of less than 1 nanometer nm or multiwalled mwcnt, consisting of several concentrically interlinked nanotubes, with diameters reaching more than 100 nm.
The production of irradiation induced defects and their migration in cnts are. The carbon atoms in nanotubes are arranged in long, hollow cylinders. Metallic catalysts for structurecontrolled growth of. Fullerenes are similar in structure to graphite, which is composed of a sheet of linked hexagonal rings, but they contain pentagonal or sometimes heptagonal rings that prevent the sheet from being planar. Manufacturing and applications of carbon nanotube sheet. With unique structures, excellent electrical, mechanical, optical and thermal properties and high specific surface area, carbon nanotubes cnts have great application in various fields 8 9. Carbon nanotubes are arousing considerable interest in both. Pdf carbon nanotubes are remarkable objects that look set to. Carbon nanotubes cnts have come a long way since their discovery in 1991 1. Here we realized the dominant growth of 16,0 tubes at the abundance near. Pdf structure and oxidation patterns of carbon nanotubes. Extreme carbon nanotubesthe longest carbon nanotube was reported in 2009 measuring 18.
Carbon nanotubes what they are, how they are made, what. This is an important building block of many carbon nano objects iso 2010b graphite allotropic form of elemental carbon comprised of graphene layers stacked in parallel to each other in a three dimensional, crystalline, longrange order. Apr 23, 2018 carbon nanotubes and related structures. The term nanotube is normally used to refer to the carbon nanotube, which. In a recent paper 18 by ko et al, the concept of formation of super carbon nanotube fibril scf by the electrospinning process was introduced. Pdf imaging electronic structure of carbon nanotubes by. Conspectussinglewalled carbon nanotubes swnts have shown great potential in various applications attributed to their unique structure dependent properties. An example of the armchair 10,10 carbon nanotube with metallic conductive properties is shown in fig. Electronic structure of n,0 zigzag carbon nanotubes. Resonance structures and aromaticity in capped carbon. To study these transitions, we first processed swnts grown in highpressure carbon monoxide hipco to obtain samples rich in individual nanotubes suspended by sds surfactant in deuterium oxide. It forms also a great variety of novel structures that are being discovered day after day these last years. The formation and growth mechanism of carbon nanotubes prepared by an arc discharge has been the subject of some controversy, particularly with regard to their micro structures. The semiconducting behaviour of these structures is due to the presence of stacking microstructure of graphene layers.
Templated synthesis of singlewalled carbon nanotubes with. Scanning tunneling microscopy stm has been used to investigate the structure and electronic properties of carbon nanotubes produced from a discharge between graphite electrodes. Oct 12, 2016 structures of carbon nanotubes the structure of a singlewall carbon nanotube is specified by the vector called chiral vector depending on the chiral indices 1,2 and chiral angle. Jul 28, 2006 the effects of vacuum annealing and oxidation in air on the structure of multiwalled carbon nanotubes mwcnts produced by a largescale catalytic chemical vapor deposition ccvd process are studied using raman spectroscopy and transmission electron microscopy tem. According to the number of graphic shells, they are mainly categorized as singlewalled swnts and multiwalled carbon nanotubes mwnts. The name is derived from the long, hollow structure with the walls formed by oneatomthick sheets of carbon, called graphene. It appears in several different forms or allotropes with widely different properties. Their unique surface area, stiffness, strength and resilience have. Jan 20, 2015 carbon nanotube seminar ppt with pdf report. In simple words the carbon nanotubes have the hexagonal cells lattice rolled onto itself with the diameters in the order of nanometers and length in the order of several micrometers. We describe experiments on synthesis of swnts with controlled molecular structures and assembly of functional macroscopic structures. Carbon is one of the elements in the nature that is present in numerous compounds and at the same time is capable of forming various crystalline structures. The structure of a carbon nanotube is formed by a layer of carbon atoms that are bonded together in a hexagonal honeycomb mesh. When the structure of atoms in a carbon nanotube minimizes the collisions between conduction electrons and atoms, a carbon nanotube is highly conductive.
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