24-03-2010, 06:38 PM
dear sir,
i am in need to present a paper on carbon nanotubes. i need imformations about thier applications, advantages and disadvantages.
24-03-2010, 06:38 PM
dear sir, i am in need to present a paper on carbon nanotubes. i need imformations about thier applications, advantages and disadvantages.
27-09-2010, 05:18 PM
please go through the following thread for more details on 'carbon nanotubes'
https://seminarproject.net/Thread-carbon...ull-report
20-02-2011, 11:39 PM
please send me a seminar on carbon nano tubes
19-04-2011, 11:38 PM
hi
you can refer these pages to get the details on nanotubes https://seminarproject.net/Thread-carbon...ull-report https://seminarproject.net/Thread-carbon...ort?page=2 https://seminarproject.net/Thread-carbon...ort?page=3
27-06-2012, 06:08 PM
CARBON NANOTUBES
CARBON NANOTUBES.ppt (Size: 640 KB / Downloads: 173) Introduction: As the process technology scales into the nanoscale regime, the impact of onchip communication on performance and reliability continues to increase. As the interconnect performance depends on both wire and driver transistor characteristics, alternative interconnect and device technologies must be investigated for onchip communication in future integrated circuits. Increasing resistivity, rising demands on current density and problems due to electromigration of copper interconnects at nanoscale regime, are driving the need for CNT’s as interconnects. IC Interconnects Interconnects in Integrated Circuit distribute Clock and other signals and provide power/ground to the various integrated circuits. The interconnect in an integrated circuit becoming the dominant factor in determining system performance and power dissipation. Interconnects are three types: Local Interconnects Connecting gates and transistors with in a functional block. Intermediate Interconnects are provides clock and signal distribution with in a functional block. Global interconnects provides clock and signal distribution between the functional blocks and deliver power/ground to all functions. Disadvantages of Using Cu Interconnects: The traditional copper interconnects will suffer from significant increase in resistivity and from electromigration problems due to lower current densities supported by the copper conductor. The increase in resistivity leads to increase in propagation delay of the signal. The standard copper (Cu) interconnect will become a major hurdle for onchip communication due to high resistivity and electromigration. Researches have proved that in copper, burn out occurred at current densities 80 MA/cm2. Properties of CNTs Carbon nanotubes are the strongest and stiffest materials yet discovered in terms of tensile strength and elastic modulus respectively. Tensile strength of 63 gigapascals (GPa). Nanotubes are very good thermal conductors, Low resistivity (~1 μΩ-cm), High current carrying capacity. The temperature stability of carbon nanotubes is estimated to be up to 2800 °C in vacuum and about 750 °C in air. Due to nanoscale dimensions, electrons propagate only along the tube's axis. Hence, carbon nanotubes are One-Dimensional. CNT’s have large current density(10^10A/cm2). which is 1000 times more than copper.
25-07-2012, 03:24 PM
Carbon nanotube
Carbon nanotube.doc (Size: 43 KB / Downloads: 85) INTRODUCTION Nanotechnology is one of the most important technologies in this century and it is evoking a new industrial revolution. Nanotechnology is changing basic research in the fields of information technology, biological science, environmental science, energy sources, material science, and others. The trend of industrial elements toward small features, high density, fast transmission, low energy cost and high production rate, has generated a greater requirement of miniaturization for elemental materials. Nanomaterial containing nanostructures are the best material to fulfill these needs. Carbon nanotubes are among the most broadly discussed, researched and applied. Since their discovery in 1991, carbon nanotubes have attracted much attention and research funding, due to the strength of their cylindrical structure, which is constructed of a hexagonal array of carbon atoms. Their structure, as well as the unique electrical, magnetic, and optic characteristics have generated a huge potential of industrial and scientific applications. The fields of carbon nanotube applications include: photo-electric elements, electric elements, biomedical science, energy materials, and artificial diamonds. International technology and industry are focused on this technology, without regard to countries, or research fields. International industrial giants with interest in this technology include IBM, Intel, and NASA in the United States, NEC, Samsung and Showa Denko Companies in Japan, and Max-Planck Institute in Germany. International technology companies are keenly interested in the application of the carbon nanotube to current and future technologies. There can be as many as 40 billion carbon nanotubes contained in a square millimeter. Carbon nanotubes are microscopic, tube-shaped structures, which essentially have a composition of a graphite sheet rolled into a tube. Carbon nanotubes have unique, interesting and potentially useful electrical and mechanical properties, and offer potential for various uses in electronic devices. Carbon nanotubes also feature extremely high electrical conductivity, very small diameters (much less than 100 nanometers), large aspect ratios (i.e. length/diameter ratios greater than 1000), and a tip-surface area near the theoretical limit (the smaller the tip-surface area, the more concentrated the electric field, and the greater the field enhancement factor). These features make carbon nanotubes ideal for electron field emitters, white light sources, lithium secondary batteries, hydrogen storage cells, transistors, and cathode ray tubes (CRTs). STUDY GOAL AND OBJECTIVES The goal of the study was to perform an exhaustive look at the field of nanocarbon materials, with a focus on single wall carbon nanotubes (SWNT), multiwall carbon nanotubes (MWNT) and fullerenes, while also investigating carbon nanofiber production and technology. More than 180 companies were found to be manufacturing nanocarbon materials that measured 100 nanometers, or less. Those companies are profiled in the report, which includes contact information. Companies that have gone out of business, or merged with other companies in the past two years, are also noted. Further, an exhaustive search was made of companies, which are incorporating carbon nanotubes and other nanocarbon materials into products that are now being sold. In addition, the study looked at products, which are under development, and are likely to enter the market in the next five to ten years. The activities of more than 900 companies and institutions in the past two years are noted. SCOPE AND FORMAT The primary focus of the report is the production of multi-wall carbon nanotubes and single wall carbon nanotubes (SWNT). However, attention is paid to producers of nano-carbon fibers that range above and below the threshold for nanotechnologies, having a measurement smaller than 100 nanometers. The report examines production of carbon nanomaterial in Europe, Asia and North America Attention is also paid to producers and consumer of graphene, which is basically an unrolled carbon nanotube, consisting of a single atom layer of carbon molecules. The report provides a brief, but thorough, update on activities in the field of carbon nanomaterials for the past two years and projects their growth through 2015. Both the International Standards Organization (ISO) and Organization for Economic Co-operation and Development (OECD) subdivide nanomaterials into “nano-objects” and “nano-structured materials.” According to ISO TS 27687, nano-objects include nanoplates, nanofibers and nanoparticles, and are nano-scale at least in their exterior measurements. In other words, they measure between one and 100 nanometers in length, width or height. Another ISO working group is currently working on the hierarchy and definitions of nanostructured materials, which include materials with a nanoscale structure within the material or on its surface. Prominent examples are nanocomposites, agglomerates and larger aggregates. REPORT SUMMARY Nanocarbon products include single-walled carbon nanotubes (SWNT) and multi-walled carbon nanotubes (MWNT), fullerenes, graphene, carbon nanofiber and nanodiamonds. Production capacity for all products increased from 996 metric tons in 2008 to more than 2190 tons in 2009 and 4065 tons of capacity in 2010, and is expected to exceed 12,300 tons in 2015, a compound annual growth rate of 24.8% a year. Total production value is expected to reach about $435 million in 2010 and reach a value of $1.3 billion in 2015.
08-11-2012, 05:25 PM
Carbon nanotubes
C-Nanotubes.ppt (Size: 535 KB / Downloads: 203) Who found first nanotube? 1970: Morinobu Endo-- First carbon filaments of nanometer dimensions, as part of his PhD studies at the University of Orleans in France. He grew carbon fibers about 7 nm in diameter using a vapor-growth technique. Filaments were not recognized as nanotubes and were not studied. 1991:Sumio Iijima-- NEC Laboratory in Tsukuba-- used high-resolution transmission electron microscopy to observe carbon nanotubes. Graphite Hexagonal graphite: Graphite has a structure containing layers of atoms arranged at the corners of contiguous hexagons. (not to be confused with hexagonal close packed). The ease with which layers slide against each other is consistent with the much larger distance between carbon atoms in different layers (335 pm) than between carbon atoms in the same layer (142 pm). The lattice constant a = 246.6 pm C=669 pm Interesting thought from paper. Quote: “Since each unit cell of a nanotube contains a number of hexagons, each of which contains two carbon atoms, the unit cell of a nanotube contains many carbon atoms. If the unit cell of a nanotube is N times larger than that of a hexagon, the unit cell of the nanotube in reciprocal space is 1/N times smaller than that of a single hexagon. “ Let us break this down! How to make nanotubes? Rice University group (1996)-- produce bundles of ordered single-wall nanotubes : Prepared by the laser vaporization of a carbon target in a furnace at 1200 °C. Cobalt-nickel catalyst helps the growth of the nanotubes, presumably because it prevents the ends from being "capped" during synthesis. By using two laser pulses 50 ns apart, growth conditions can be maintained over a larger volume and for a longer time. This scheme provides more uniform vaporization and better control of the growth conditions. Flowing argon gas sweeps the nanotubes from the furnace to a water-cooled copper collector just outside of the furnace. Catherine Journet, Patrick Bernier and colleagues at the University of Montpellier in France: carbon-arc method to grow arrays of single-wall nanotubes.
23-12-2013, 09:10 PM
u can try in world of teaching website for ppts..
ALL THE BEST
05-01-2014, 09:40 AM
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18-03-2014, 10:06 AM
Abstract Carbon nanotubes (CNTs) are a recently discovered allotrope of carbon. They take the form of cylindrical carbon molecules and have novel properties that make them potentially useful in a wide variety of applications in nanotechnology, electronics, optics, and other fields of materials science. They exhibit extraordinary strength and unique electrical properties, and are efficient conductors of heat. Inorganic nanotubes have also been synthesized. A nanotube is a member of the fullerene structural family, which also includes buckyballs. Whereas buckyballs are spherical in shape, a nanotube is cylindrical, with at least one end typically capped with a hemisphere of the buckyball structure. Their name is derived from their size, since the diameter of a nanotube is on the order of a few nanometers (approximately 50,000 times smaller than the width of a human hair), while they can be up to several millimeters in length. There are two main types of nanotubes: single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs). Manufacturing a nanotube is dependent on applied quantum chemistry, specifically, orbital hybridization. Nanotubes are composed entirely of sp2 bonds, similar to those of graphite. This bonding structure, stronger than the sp3 bonds found in diamond, provides the molecules with their unique strength. Nanotubes naturally align themselves into "ropes" held together by Van der Waals forces. Under high pressure, nanotubes can merge together, trading some sp2 bonds for sp3 bonds, giving great possibility for producing strong, unlimited-length wires through high-pressure nanotube linking |
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