Download or read book Conductive Effect of Increased Crystallinity of Single Walled Carbon Nanotubes as Field Emitter written by Norihiro Shimoi and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes (CNTs) exhibit chemical stability, thermal conductivity, mechanical strength, and unique properties as a quasi-one-dimensional material with nanoscale needle shape. Field-emission (FE) electron sources appear to be the most promising industrial application for CNTs, and their deployment is approaching practical utilization. So far, efforts to construct an FE cathode with single-walled carbon nanotubes (SWCNTs) have only managed to average out the large FE current fluctuations in a nonhomogeneous electron emitter plane and the short emission lifetime because the crystal defects in the carbon network in CNTs prevent the realization of a stable emission current. The utilization of CNTs to obtain an effective electronic device, one with stable emission and low FE current fluctuations, relies on the high crystallization of CNTs, a task that can be fulfilled by using highly crystalline SWCNTs (hc-SWCNTs). The author could succeed in developing a model of the flow of electrons through the inside of the hc-SWCNTs and SWCNTs with crystal defects to the outside using the fluctuations of the tunneling current. Therefore, we expect that the hc-SWCNTs are used as field emitters with stable emission and low power consumption for saving energy.

Download or read book Perspective of Carbon Nanotubes written by Hosam El-Din Saleh and published by BoD – Books on Demand. This book was released on 2019-12-11 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes belong to new nanomaterials and have been known for almost 20 years, but their history is somewhat lengthier. They have been identified as promising candidates for various applications.High-temperature preparation techniques are conventional techniques for the synthesis of carbon nanotubes using arc discharge or laser ablation, but today these methods are being replaced by low-temperature vapor deposition techniques, since orientation, alignment, nanotube length, diameter, purity, and density of carbon nanotubes can be precisely controlled. The synthesis of carbon nanotubes by chemical vapor deposition on catalyst arrays leads to nanotube models grown from specific sites on surfaces. The controlled synthesis of nanotubes opens up interesting possibilities in nanoscience and nanotechnologies, including electrical, mechanical and electromechanical properties and devices, chemical functionalization, surface chemistry and photochemistry, molecular sensors, and interfacing with moderate biological systems.Carbon nanotubes are used in many applications due to their unique electrical, mechanical, optical, thermal, and other properties. Conductive and high-strength composite materials, energy saving and energy conversion devices, sensors, visualization of field emissions and sources of radiation, means for storing hydrogen, and nanoscale semiconductor devices, probes, and interconnections are some of the many applications of carbon nanotubes.

Download or read book Carbon Nanotubes written by Mohammed Rahman and published by BoD – Books on Demand. This book was released on 2018-04-26 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book Carbon Nanotubes - Recent Progress contains a number of recent researches on synthesis, growth, characterization, development, and potential applications on carbon materials especially CNTs in nanoscale. It is a promising novel research from top to bottom that has received a lot of interest in the last few decades. It covers the advanced topics on the physical, chemical, and potential applications of CNTs. Here, the interesting reports on cutting-edge science and technology related to synthesis, morphology, control, hybridization, and prospective applications of CNTs are concluded. This potentially unique work offers various approaches on the R

Download or read book Stability and Reliability of an Electrical Device Employing Highly Crystalline Single Walled Carbon Nanotubes as a Field Emitter written by Norihiro Shimoi and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanomaterial is drawing keen interest from researchers as well as materials scientists. Carbon nanotubes (CNTs)-and their nanoscale needle shape-offering chemical stability, thermal conductivity, and mechanical strength exhibit unique properties as a quasi-one-dimensional material. Among the expected applications, field emission electron sources appear the most promising industrially and are approaching practical utilization. However, efforts to construct a field emission (FE) cathode with single-walled carbon nanotubes (SWCNTs) have so far only helped average out a non-homogeneous electron emitter plane with large FE current fluctuations and a short emission life-time because they failed to realize a stable emission current owing to crystal defects of the carbon network in CNTs. The utilization of CNTs to obtain an effective cathode, one with a stable emission and low FE current fluctuation, relies on the ability to disperse CNTs uniformly in liquid media. In particular, highly crystalline SWCNTs hold promise to obtain good stability and reliability. The author successfully manufactured highly crystalline SWCNTs-based FE lighting elements that exhibit stable electron emission, a long emission life-time, and low power consumption for electron emitters. This FE device employing highly crystalline SWCNTs has the potential for conserving energy through low power consumption in our habitats.

Download or read book Nanotube Cathodes written by Paul Albert Miller and published by . This book was released on 2006 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes have shown promise for applications in many diverse areas of technology. In this report we describe our efforts to develop high-current cathodes from a variety of nanotubes deposited under a variety of conditions. Our goal was to develop a one-inch-diameter cathode capable of emitting 10 amperes of electron current for one second with an applied potential of 50 kV. This combination of current and pulse duration significantly exceeds previously reported nanotube-cathode performance. This project was planned for two years duration. In the first year, we tested the electron-emission characteristics of nanotube arrays fabricated under a variety of conditions. In the second year, we planned to select the best processing conditions, to fabricate larger cathode samples, and to test them on a high-power relativistic electron beam generator. In the first year, much effort was made to control nanotube arrays in terms of nanotube diameter and average spacing apart. When the project began, we believed that nanotubes approximately 10 nm in diameter would yield sufficient electron emission properties, based on the work of others in the field. Therefore, much of our focus was placed on measured field emission from such nanotubes grown on a variety of metallized surfaces and with varying average spacing between individual nanotubes. We easily reproduced the field emission properties typically measured by others from multi-wall carbon nanotube arrays. Interestingly, we did this without having the helpful vertical alignment to enhance emission; our nanotubes were randomly oriented. The good emission was most likely possible due to the improved crystallinity, and therefore, electrical conductivity, of our nanotubes compared to those in the literature. However, toward the end of the project, we learned that while these 10-nm-diameter CNTs had superior crystalline structure to the work of others studying field emission from multi-wall CNT arrays, these nanotubes still had a thin coating of glassy carbon surrounding them in a sheath-like manner. This glassy carbon, or nano-crystalline graphite, is likely to be a poor conductor due to phonon scattering, and should actually be deleterious for extracting electrons with electric fields. While we did not achieve the field emission reported for single-wall carbon nanotubes that spurred the idea for this project, at the year's very end, we had a breakthrough in materials growth and learned to control the growth of very-small diameter nanotubes ranging from 1.4 to 7 nm. The 1.4-nm nanotubes are single-walled and grow at only 530 C. This is the lowest temperature known to result in single-wall carbon nanotubes, and may be very important for many applications that where certain substrates could not be used due to the high temperatures commonly used for CNT growth. Critically important for field emission, these small diameter nanotubes, consisting of only a few concentric graphene cylindrical walls, do not show the presence of a poorly-conductive sheath material. Therefore, these nanotubes will almost definitely have superior field emission properties to those we already measured, and it is possible that they could provide the necessary field emission to make this project successful. Controlled spacing and lengths of these single-wall nanotubes have yet to be explored, along with correlating their structures to their improved field emission. Unfortunately, we did not discover the methods to grow these highly-crystalline and small diameter CNTs until late in the year. Since we did not achieve the necessary emission properties by mid-year, the project was ''prematurely'' terminated prior to the start of the second year. However, it should be noted that with the late developments, this work has not hit the proverbial ''brick wall''. Clearly the potential still exists to reproduce and even exceed the high emission results reported for randomly-oriented and curly single-wall carbon nanotubes, both in terms of total field emitting currents and perhaps more importantly, in reproducibility.

Download or read book Optical and Mechanical Properties of Single walled Carbon Nanotubes written by Matthew S. Marcus and published by . This book was released on 2004 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Harnessing the Properties of Carbon Nanotubes to Increase Applicability written by Christopher Rotella and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes have been an interest in the field of materials research since their identification in 1991. They boast robust mechanical, electrical, thermal, and chemical properties that make them desirable for a wide range of applications. A main feature that is studied heavily in this work is their acceptance of many different chemical dopants. Dopants such as B, N, Si, and S have been utilized in previous works, all showing unique changes to the physical properties of CNTs, allowing them to be tailored to different applications. This thesis seeks to further increase the applicability of CNTs through various methods, for both broad and specific applications.Nitrogen and silicon doping and their affect on both single- and multi-walled carbon nanotubes is studied in the effort of controlling their growth parameters. By introducing a growth aid in the form of ethanol, heights of vertically aligned N-doped multi-walled tubes were extended over 200% from heights with no growth aid. This is done through the extension of the catalytic activity time by etching amorphous carbon that deposits. Results suggest that the density and size of the catalyst particles plays a large factor in the concentration of growth aid required to effectively extend growth times. Silicon doping of single-walled tubes was achieved experimentally through the use of the precursor methoxytrimethylsilane inside the precursor solution of an aerosol-assisted chemical vapor deposition system. It is reported here that higher concentrations of the silicon precursor (>0.15wt% in solution) have an adverse effect of the growth of CNTs, effectively poisoning the catalyst. At lower concentrations, however, the silicon precursor contributes to a decrease in average tube diameter and an increase in overall lattice disorder, observed through the use of Raman spectroscopy. Fitting electrical resistance measurements as a function of temperature to Motts variable range hopping models allowed us to determine the mechanism behind electron conductance between nanotubes in bundles. The data suggests that electrons move in a 3-dimensional hopping pattern for bundles of pristine single-walled nanotubes, confirming theoretical previous research. For samples with small concentrations of silicon precursor present, the electron hopping changes to a mix between 2- and 3-dimensional. This indicates that the silicon adatoms act as a scattering point for electrons, directing them to neighboring tubes with a dimensionality factor of two. Further theoretical models were used to study the effect of single or multiple silicon adatoms on neighboring single-walled tubes and their effect on conductance between those tubes. This data suggests that the inclusion of any silicon dopants increases the conductance between the tubes, compared to pristine tubes.Interconnected networks of multi-walled tubes were formed through the use of welding and annealing. The networks were formed through first cross-aligning sheets of CNTs and ensuring physical contact between them. Following this, Ar was bubbled through ethanol and introduced to the sample inside a tube furnace. The ethanol deposited carbon on the nanotube networks, effectively welding them together. Subsequent tubes increased dramatically in diameter from the original tubes, though the outer walls lacked the crystallinity found in the original tubes. Through an anneal at 2200 the overall crystallinity was increased, measured through Raman spectroscopy, high-resolution transmission electron microscopy, and fast Fourier transform. Mechanical testing was performed on the original, welded, and annealed samples to compare tensile strength. The welding process improved the tensile strength by 38%, and the further annealing increased the tensile strength by 66% of the original value. By pre-patterning the iron catalyst used to grow CNTs onto the substrate through the use of photolithography, patterned arrays of vertically aligned CNTs can be formed. These arrays were then utilized as filters to trap viruses through the devices encapsulation in a polymer mold. The CNT-STEP (size tunable enrichment platform) devices were utilized in this work towards the trapping and understanding of the tomato-spotted wilt virus (TSWV). TSWV is a virus that infects upwards of 1000 different plants across the globe and is responsible for massive monetary losses in damages annually. The problems containing the virus stem from the fast nature at which it is able to be spread to neighboring plants, the long time in between inoculation and symptoms (2 weeks), and its inability to be detected prior to symptom onset. Our CNT-STEP devices were utilized to trap the TSWV viruses with the arrays of aligned tubes, allowing larger and smaller contaminants to be removed from the sample. This process effectively hyper-concentrates the viruses, allowing conventional detection methods to be able to detect the viruses. Experimental data shows that the devices were able to effectively trap the viruses, but further processing is required to optimize the system in order to achieve enhancement (where previously undetectable low concentrations are hyper-concentrated in devices in order to be effectively detected).Interconnected networks of single-walled tubes were used as a backbone to support an active battery material (LNMC) to create flexible lithium-ion battery cathodes. Carbon nanotubes are able to effectively replace the metal current collectors and the polymer binders commonly used in Li-ion battery electrodes. By replacing these components with CNTs, the surface area of functional material is increased, while decreasing the weight. Novel methods were utilized to aerosolize powdered LNMC while simultaneously growing and depositing single-walled tubes to create an even dispersion. The CNTs provide mechanical support to the structure, while also being the main contributor to electrical conductivity in the sample. The weight percentage of CNTs in the sample is able to be tuned, with more flexible and mechanically robust samples having >5 wt% CNTs. The ideal samples were grown with between 1-3 wt % CNTs, as higher CNT content made samples increasingly difficult to process, due to inherent adhesion to all surfaces. Simultaneous tensile and resistance measurements were performed to compare growth parameters. Samples were able to withstand 10% elongation at break, but lower stresses than the materials they look to replace. Samples showed overall decreases in resistivity after multiple cycles of elongation and relaxation, indicating small amounts of disorder in the network that are eliminated through stretching. Overall the samples showed excellent promise for use in flexible battery electrodes. Through the use of chemical doping, and strict growth parameter control, the applicability of CNTs can be widely increased.

Download or read book Fundamentals of Conjugated Polymer Blends Copolymers and Composites written by Parveen Saini and published by John Wiley & Sons. This book was released on 2015-04-30 with total page 684 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since their discovery in 1977, the evolution of conducting polymers has revolutionized modern science and technology. These polymers enjoy a special status in the area of materials science yet they are not as popular among young readers or common people when compared to other materials like metals, paper, plastics, rubber, textiles, ceramics and composites like concrete. Most importantly, much of the available literature in the form of papers, specific review articles and books is targeted either at advanced readers (scientists / technologists / engineers / senior academicians) or for those who are already familiar with the topic (doctoral / postdoctoral scholars). For a beginner or even school / college students, such compilations are bit difficult to access / digest. In fact, they need proper introduction to the topic of conducting polymers including their discovery, preparation, properties, applications and societal impact, using suitable examples and already known principles/knowledge/phenomenon. Further, active participation of readers in terms of "question & answers", "fill-in-the-blanks", "numerical" along with suitable answer key is necessary to maintain the interest and to initiate the "thought process". The readers also need to know about the drawbacks and any hazards of such materials. Therefore, I believe that a comprehensive source on the science / technology of conducting polymers which maintains a link between grass root fundamentals and state-of-the-art R&D is still missing from the open literature.

Download or read book Carbon Nanotube Polymer Composites written by Dimitrios Tasis and published by Royal Society of Chemistry. This book was released on 2015-11-09 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemically-modified carbon nanotubes (CNTs) exhibit a wide range of physical and chemical properties which makes them an attractive starting material for the preparation of super-strong and highly-conductive fibres and films. Much information is available across the primary literature, making it difficult to obtain an overall picture of the state-of-the-art. This volume brings together some of the leading researchers in the field from across the globe to present the potential these materials have, not only in developing and characterising novel materials but also the devices which can be fabricated from them. Topics featured in the book include Raman characterisation, industrial polymer materials, actuators and sensors and polymer reinforcement, with chapters prepared by highly-cited authors from across the globe. A valuable handbook for any academic or industrial laboratory, this book will appeal to newcomers to the field and established researchers alike.

Download or read book Multi Walled Carbon Nanotubes written by Simone Morais and published by . This book was released on 2019 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since their discovery, multi-walled carbon nanotubes (MWCNTs) have received tremendous attention due to their unique electrical, optical, physical, chemical, and mechanical properties. Remarkable advances have been made in the synthesis, purification, structural characterization, functionalization, and application of MWCNTs. Their particular characteristics make them well suited for a plethora of applications in a number of fields, namely nanoelectronics, nanofluids, energy management, (electro)catalysis, materials science, construction of (bio)sensors based on different detection schemes, multifunctional nanoprobes for biomedical imaging, and sorbents for sample preparation or removal of contaminants from wastewater. They are also useful as anti-bacterial agents, drug delivery nanocarriers, etc. The current relevant application areas are countless. This Special Issue presents original research and review articles that address advances, trends, challenges, and future perspectives regarding synthetic routes, structural features, properties, behaviors, and industrial or scientific applications of MWCNTs in established and emerging areas.

Download or read book Carbon Based Electronics written by Ashok Srivastava and published by CRC Press. This book was released on 2015-03-19 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: Discovery of one-dimensional material carbon nanotubes in 1991 by the Japanese physicist Dr. Sumio Iijima has resulted in voluminous research in the field of carbon nanotubes for numerous applications, including possible replacement of silicon used in the fabrication of CMOS chips. One interesting feature of carbon nanotubes is that these can be me

Download or read book Carbon Nanotubes written by Mohamed Berber and published by BoD – Books on Demand. This book was released on 2016-07-20 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book shows the recent advances of the applications of carbon nanotubes (CNTs), in particular, the polymer functionalized carbon nanotubes. It also includes a comprehensive description of carbon nanotubes' preparation, properties, and characterization. Therefore, we have attempted to provide detailed information about the polymer-carbon nanotube composites. With regard to the unique structure and properties of carbon nanotubes, a series of important findings have been reported. The unique properties of carbon nanotubes, including thermal, mechanical, and electrical properties, after polymer functionalization have been documented in detail. This book comprises 18 chapters. The chapters include different applications of polymer functionalization CNTs, e.g. photovoltaic, biomedical, drug delivery, gene delivery, stem cell therapy, thermal therapy, biological detection and imaging, electroanalytical, energy, supercapacitor, and gas sensor applications.

Download or read book Oxford Handbook of Nanoscience and Technology written by A.V. Narlikar and published by Oxford University Press. This book was released on 2010-02-11 with total page 957 pages. Available in PDF, EPUB and Kindle. Book excerpt: These three volumes are intended to shape the field of nanoscience and technology and will serve as an essential point of reference for cutting-edge research in the field.

Download or read book Carbon Nanotubes written by Stephanie Reich and published by John Wiley & Sons. This book was released on 2008-09-26 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes are exceptionally interesting from a fundamental research point of view. Many concepts of one-dimensional physics have been verified experimentally such as electron and phonon confinement or the one-dimensional singularities in the density of states; other 1D signatures are still under debate, such as Luttinger-liquid behavior. Carbon nanotubes are chemically stable, mechanically very strong, and conduct electricity. For this reason, they open up new perspectives for various applications, such as nano-transistors in circuits, field-emission displays, artificial muscles, or added reinforcements in alloys. This text is an introduction to the physical concepts needed for investigating carbon nanotubes and other one-dimensional solid-state systems. Written for a wide scientific readership, each chapter consists of an instructive approach to the topic and sustainable ideas for solutions. The former is generally comprehensible for physicists and chemists, while the latter enable the reader to work towards the state of the art in that area. The book gives for the first time a combined theoretical and experimental description of topics like luminescence of carbon nanotubes, Raman scattering, or transport measurements. The theoretical concepts discussed range from the tight-binding approximation, which can be followed by pencil and paper, to first-principles simulations. We emphasize a comprehensive theoretical and experimental understanding of carbon nanotubes including - general concepts for one-dimensional systems - an introduction to the symmetry of nanotubes - textbook models of nanotubes as narrow cylinders - a combination of ab-initio calculations and experiments - luminescence excitation spectroscopy linked to Raman spectroscopy - an introduction to the 1D-transport properties of nanotubes - effects of bundling on the electronic and vibrational properties and - resonance Raman scattering in nanotubes.

Download or read book Springer Handbook of Nanomaterials written by Robert Vajtai and published by Springer Science & Business Media. This book was released on 2013-08-20 with total page 1234 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Springer Handbook of Nanomaterials covers the description of materials which have dimension on the "nanoscale". The description of the nanomaterials in this Handbook follows the thorough but concise explanation of the synergy of structure, properties, processing and applications of the given material. The Handbook mainly describes materials in their solid phase; exceptions might be e.g. small sized liquid aerosols or gas bubbles in liquids. The materials are organized by their dimensionality. Zero dimensional structures collect clusters, nanoparticles and quantum dots, one dimensional are nanowires and nanotubes, while two dimensional are represented by thin films and surfaces. The chapters in these larger topics are written on a specific materials and dimensionality combination, e.g. ceramic nanowires. Chapters are authored by well-established and well-known scientists of the particular field. They have measurable part of publications and an important role in establishing new knowledge of the particular field.

Download or read book Single Walled Carbon Nanotubes written by Yan Li and published by Springer. This book was released on 2019-05-16 with total page 333 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series Topics in Current Chemistry Collections presents critical reviews from the journal Topics in Current Chemistry organized in topical volumes. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field.

Download or read book Temperature Effects on the Electronic Conductivity of Single walled Carbon Nanotubes written by Mark Daniel Mascaro and published by . This book was released on 2007 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: The room-temperature electronic conductivity and temperature dependence of conductivity were measured for samples of carbon nanotubes of three types: pristine; functionalized with a nitrobenzene covalent functionalization, which are expected to display poor electronic conductivity; and functionalized with a carbene covalent functionalization, which are expected to display pristine-like conductivity. Measurements were taken via four-point probe measurement across palladium contacts on a silicon surface coated with a distribution of nanotubes. Room-temperature measurements indicate that carbene-functionalized tubes do exhibit significantly greater conductivity than nitrobenzene-functionalized tubes, but also significantly less than pristine tubes. Statistically different distributions of resistances observed in similarly prepared samples indicate that this measurement technique is strongly affected by uncontrollable and so far uncharacterizable parameters of the employed sample preparation technique. Measurements at varying temperature indicate the expected linear relationship of resistance and temperature is dominated in pristine and carbene samples by a effect, possibly contamination-related, which significantly and permanently increases the resistance of samples after cycling to high temperatures, and which occurs repeatedly with additional cycling. Carbene-functionalized samples were observed to exhibit similar temperature behavior to pristine samples, while nitrobenzene-functionalized samples displayed erratic, unpredictable behavior.