Download or read book Field Emission Properties of Carbon Nanotube Fibers and Sheets for a High Current Electron Source written by Larry A. Christy and published by . This book was released on 2014 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt: Field emission (FE) properties of carbon nanotube (CNT) fibers from Rice University and the University of Cambridge have been studied for use within a high current electron source for a directed energy weapon. Upon reviewing the performance of these two prevalent CNT fibers, cathodes were designed with CNT fibers from the University of Cincinnati Nanoworld Laboratory. Cathodes composed of a single CNT fiber, an array of three CNT fibers, and a nonwoven CNT sheet were investigated for FE properties; the goal was to design a cathode with emission current in excess of 10 mA. Once the design phase was complete, the cathode samples were fabricated, characterized, and then analyzed to determine FE properties. Electrical conductivity of the CNT fibers was characterized with a 4-probe technique. FE characteristics were measured in an ultra-high vacuum chamber at Wright-Patterson Air Force Base. The arrayed CNT fiber and the enhanced nonwoven CNT sheet emitter design demonstrated the most promising FE properties. Future work will include further analysis and cathode design using this nonwoven CNT sheet material to increase peak current performance during electron emission.

Download or read book Carbon Nanotube and Related Field Emitters written by Yahachi Saito and published by John Wiley & Sons. This book was released on 2010-10-01 with total page 551 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes (CNTs) have novel properties that make them potentially useful in many applications in nanotechnology, electronics, optics and other fields of materials science. These characteristics include extraordinary strength, unique electrical properties, and the fact that they are efficient heat conductors. Field emission is the emission of electrons from the surface of a condensed phase into another phase due to the presence of high electric fields. CNT field emitters are expected to make a breakthrough in the development of field emission display technology and enable miniature X-ray sources that will find a wide variety of applications in electronic devices, industry, and medical and security examinations. This first monograph on the topic covers all aspects in a concise yet comprehensive manner - from the fundamentals to applications. Divided into four sections, the first part discusses the preparation and characterization of carbon nanotubes, while part two is devoted to the field emission properties of carbon nanotubes, including the electron emission mechanism, characteristics of CNT electron sources, and dynamic behavior of CNTs during operation. Part three highlights field emission from other nanomaterials, such as carbon nanowalls, diamond, and silicon and zinc oxide nanowires, before concluding with frontier R&D applications of CNT emitters, from vacuum electronic devices such as field emission displays, to electron sources in electron microscopes, X-ray sources, and microwave amplifiers. Edited by a pioneer in the field, each chapter is written by recognized experts in the respective fields.

Download or read book Nanostructured Carbon Electron Emitters and Their Applications written by Yahachi Saito and published by CRC Press. This book was released on 2022-01-27 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon forms a variety of allotropes due to the diverse hybridization of s- and p-electron orbitals, including the time-honored graphite and diamond as well as new forms such as C60 fullerene, nanotubes, graphene, and carbyne. The new family of carbon isotopes—fullerene, nanotubes, graphene, and carbyne—is called “nanostructured carbon” or “nanocarbon.” These isotopes exhibit extreme properties such as ultrahigh mechanical strength, ultrahigh charge–carrier mobility, and high thermal conductivity, attracting considerable attention for their electronic and mechanical applications as well as for exploring new physics and chemistry in the field of basic materials science. Electron sources are important in a wide range of areas, from basic physics and scientific instruments to medical and industrial applications. Carbon nanotubes (CNTs) and graphene behave as excellent electron-field emitters owing to their exceptional properties and offer several benefits compared to traditional cathodes. Field emission (FE) produces very intense electron currents from a small surface area with a narrow energy spread, providing a highly coherent electron beam—a combination that not only provides us with the brightest electron sources but also explores a new field of electron beam–related research. This book presents the enthusiastic research and development of CNT-based FE devices and focuses on the fundamental aspects of FE from nanocarbon materials, including CNTs and graphene, and the latest research findings related to it. It discusses applications of FE to X-ray and UV generation and reviews electron sources in vacuum electronic devices and space thrusters. Finally, it reports on the new forms of carbon produced via FE from CNT.

Download or read book Carbon Nanotubes written by Michael J. O’Connell and published by CRC Press. This book was released on 2018-10-03 with total page 339 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since their discovery more than a decade ago, carbon nanotubes (CNTs) have held scientists and engineers in captive fascination, seated on the verge of enormous breakthroughs in areas such as medicine, electronics, and materials science, to name but a few. Taking a broad look at CNTs and the tools used to study them, Carbon Nanotubes: Properties and Applications comprises the efforts of leading nanotube researchers led by Michael O’Connell, protégé of the late father of nanotechnology, Richard Smalley. Each chapter is a self-contained treatise on various aspects of CNT synthesis, characterization, modification, and applications. The book opens with a general introduction to the basic characteristics and the history of CNTs, followed by discussions on synthesis methods and the growth of “peapod” structures. Coverage then moves to electronic properties and band structures of single-wall nanotubes (SWNTs), magnetic properties, Raman spectroscopy of electronic and chemical behavior, and electromechanical properties and applications in NEMS (nanoelectromechanical systems). Turning to applications, the final sections of the book explore mechanical properties of SWNTs spun into fibers, sidewall functionalization in composites, and using SWNTs as tips for scanning probe microscopes. Taking a fresh look at this burgeoning field, Carbon Nanotubes: Properties and Applications points the way toward making CNTs commercially viable.

Download or read book Convergence of Terahertz Sciences in Biomedical Systems written by Gun-Sik Park and published by Springer Science & Business Media. This book was released on 2012-10-19 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent technological breakthrough in the field of Terahertz radiation has triggered new applications in biology and biomedicine. Particularly, biological applications are based on the specific spectroscopic fingerprints of biological matter in this spectral region. Historically with the discovery of new electromagnetic wave spectrum, we have always discovered new medical diagnostic imaging systems. The use of terahertz wave was not realized due to the absence of useful terahertz sources. Now after successful generation of THz waves, it is reported that a great potential for THz wave exists for its resonance with bio-molecules. There are many challenging issues such as development of THz passive and active instrumentations, understanding of THz-Bio interaction for THz spectroscopy, THz-Bio nonlinear phenomena and safety guideline, and THz imaging systems. Eventually the deeper understanding of THz-Bio interaction and novel THz systems enable us to develop powerful THz biomedical imaging systems which can contribute to biomedical industry. This is a truly interdisciplinary field and convergence technology where the communication between different disciplines is the most challenging issue for the success of the great works. One of the first steps to promote the communications in this convergence technology would be teaching the basics of these different fields to the researchers in a plain language with the help of Convergence of Terahertz Science in Biomedical Systems which is considered to be 3-4th year college students or beginning level of graduate students. Therefore, this type of book can be used by many people who want to enter or understand this field. Even more it can be used for teaching in universities or research institutions.

Download or read book Nanotube Superfiber Materials written by Mark Schulz and published by William Andrew. This book was released on 2013-09-16 with total page 861 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanotube Superfiber Materials refers to different forms of macroscale materials with unique properties constructed from carbon nanotubes. These materials include nanotube arrays, ribbons, scrolls, yarn, braid, and sheets. Nanotube materials are in the early stage of development and this is the first dedicated book on the subject. Transitioning from molecules to materials is a breakthrough that will positively impact almost all industries and areas of society. Key properties of superfiber materials are high flexibility and fatigue resistance, high energy absorption, high strength, good electrical conductivity, high maximum current density, reduced skin and proximity effects, high thermal conductivity, lightweight, good field emission, piezoresistive, magnetoresistive, thermoelectric, and other properties. These properties will open up the door to dozens of applications including replacing copper wire for power conduction, EMI shielding, coax cable, carbon biofiber, bullet-proof vests, impact resistant glass, wearable antennas, biomedical microdevices, biosensors, self-sensing composites, supercapacitors, superinductors, hybrid superconductor, reinforced elastomers, nerve scaffolding, energy storage, and many others. The scope of the book covers three main areas: Part I: Processing; Part II: Properties; and Part III: Applications. Processing involves nanotube synthesis and macro scale material formation methods. Properties covers the mechanical, electrical, chemical and other properties of nanotubes and macroscale materials. Different approaches to growing high quality long nanotubes and spinning the nanotubes into yarn are explained in detail. The best ideas are collected from all around the world including commercial approaches. Applications of nanotube superfiber cover a huge field and provides a broad survey of uses. The book gives a broad overview starting from bioelectronics to carbon industrial machines. - First book to explore the production and applications of macro-scale materials made from nano-scale particles - Sets out the processes for producing macro-scale materials from carbon nanotubes, and describes the unique properties of these materials - Potential applications for CNT fiber/yarn include replacing copper wire for power conduction, EMI shielding, coax cable, carbon biofiber, bullet-proof vests, impact resistant glass, wearable antennas, biomedical microdevices, biosensors, self-sensing composites, supercapacitors, superinductors, hybrid superconductor, reinforced elastomers, nerve scaffolding, energy storage, and many others

Download or read book Commission de Londres 27 28 f vr 1911 written by and published by . This book was released on 1911 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Physics of Carbon Nanotube Devices written by Francois Leonard and published by William Andrew. This book was released on 2008-11-18 with total page 411 pages. Available in PDF, EPUB and Kindle. Book excerpt: Possibly the most impactful material in the nanotechnology arena, carbon nanotubes have spurred a tremendous amount of scientific research and development. Their superior mechanical and chemical robustness makes them easily manipulable and allows for the assembly of various types of devices, including electronic, electromechanical, opto-electronic and sensing devices.In the field of nanotube devices, however, concepts that describe the properties of conventional devices do not apply. Carbon nanotube devices behave much differently from those using traditional materials, and offer entirely new functionality. This book – designed for researchers, engineers and graduate students alike – bridges the experimental and theoretical aspects of carbon nanotube devices. It emphasizes and explains the underlying physics that govern their working principles, including applications in electronics, nanoelectromechanical systems, field emission, optoelectronics and sensing. Other topics include: electrical contacts, p-n junctions, transistors, ballistic transport, field emission, oscillators, rotational actuators, electron-phonon scattering, photoconductivity, and light emission. Many of the aspects discussed here differ significantly from those learned in books or traditional materials, and are essential for the future development of carbon nanotube technology.• Bridges experimental and theoretical aspects of carbon nanotube devices, focusing on the underlying physics that govern their working principles • Explains applications in electronics, nanoelectromechanical systems, field emission, optoelectronics and sensing. • Other topics include: electrical contacts, p-n junctions, transistors, ballistic transport, field emission, oscillators, rotational actuators, electron-phonon scattering, photoconductivity, and light emission. • Covers aspects that significantly differ from those learned in traditional materials, yet are essential for future advancement of carbon nanotube technology.* Bridges experimental and theoretical aspects of carbon nanotube devices, focusing on the underlying physics that govern their working principles * Explains applications in electronics, nanoelectromechanical systems, field emission, optoelectronics and sensing.* Other topics include: electrical contacts, p-n junctions, transistors, ballistic transport, field emission, oscillators, rotational actuators, electron-phonon scattering, photoconductivity, and light emission* Covers aspects that significantly differ from those learned in traditional materials, yet are essential for future advancement of carbon nanotube technology.

Download or read book Fabrication Field Emission Properties and Theoretical Simulation of Triode type Carbon Nanotube Emitter Arrays written by Jianfeng Wu and published by . This book was released on 2010 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes exhibit excellent field emission properties and will likely be prime candidates as electron sources in future vacuum electronic applications. Recent research has focused on enhancing field emission from traditional diode-type emitters by adding a gate electrode between the anode and the cathode. Since the gate to cathode (emitter) distance in this triode-type structure is small relative to the anode to cathode distance, this structure allows relatively small gate voltages to significantly enhance or dampen field emission. The key challenge for this research is: synthesizing vertically aligned carbon nanotube field emitters inside arrays of triode-type devices. The most common "top-down", etch-deposit-synthesis method of synthesizing carbon nanotubes inside gated cavities is discussed here, and a novel "bottom-up" method is presented. This new approach bypasses the lithography and wet chemistry essential to the etch-deposit-synthesis method, instead using a dual-beam focused ion beam (FIB) system to mill cavities into a multi-layered substrate. Here the substrate is designed such that the act of milling a hole simultaneously creates the gate structure and exposes the catalyst from which carbon nanotubes can then be grown. Carbon nanotubes are synthesized using plasma enhanced chemical vapor deposition (PECVD) rather than thermal chemical vapor deposition, due to the superior alignment of the PECVD growth. As dual-beam FIB and PECVD can both be largely computerized, this synthesis method is highly reproducible. The dual-beam FIB also permits a high degree of controllability in gate radius, cavity depth and emitter spacing. The effects of a host of PECVD growth parameters (initial catalyst thickness, gas concentration, growth temperature, temperature ramping rate, chamber pressure, and plasma voltage) were characterized so that the morphology of the carbon nanotube emitters could be controlled as well. This "bottom-up" method is employed to construct functional, large area carbon nanotube field emitter arrays (CNT FEAs). The role of the gate layer in field emission is examined experimentally as well as through theoretical models. Field emission testing revealed that increasing gate voltage by as little as 0.3 V had significant impact on the local electric fields, lowering the turn-on and threshold fields by 3.6 and 3.0 V/um, respectively, and increasing the field enhancement factor from 149 to 222. A quantum mechanical model of such triode-type field emission indicates that the local electric field generated by a negatively or positively biased gate directly impacts the tunneling barrier thickness and thus the achievable emission current. However, the geometry of triode-type devices (gate height, gate radius, emitter density) can influence the degree to which the gate voltage influences field emission. I demonstrate here an effective method of analytically calculating the effect of various such geometric parameters on the field emission. Results show that gate type (the height of the gate relative the emitter tip) can significantly impact the local electric field and hence the type of applications a device is suitable for. Side gates (gate height emitter height) induced the highest local electric field, while top gates (gate height emitter height) provided the greatest controllability. For all gate types, increasing the size of the gate opening increased the local electric field by diminishing the gate-emitter screening effect. However, gate voltages were able to enhance or inhibit the local electric field much more readily with smaller gate radii. Due to the strength of gate-emitter field screening in the triode-type structure, the spacing between emitters had virtually no impact on the local electric field, allowing relatively high emitter densities. These theoretical results, combined with a highly controllable synthesis method, provide valuable information and methodology for those designing and optimizing triode-type devices targeted at specific applications.

Download or read book Kirk Othmer Concise Encyclopedia of Chemical Technology 2 Volume Set written by Kirk-Othmer and published by John Wiley & Sons. This book was released on 2007-07-16 with total page 2762 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is an easily-accessible two-volume encyclopedia summarizing all the articles in the main volumes Kirk-Othmer Encyclopedia of Chemical Technology, Fifth Edition organized alphabetically. Written by prominent scholars from industry, academia, and research institutions, the Encyclopedia presents a wide scope of articles on chemical substances, properties, manufacturing, and uses; on industrial processes, unit operations in chemical engineering; and on fundamentals and scientific subjects related to the field.

Download or read book Carbon Nanotubes written by Michael J. O’Connell and published by CRC Press. This book was released on 2018-10-03 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since their discovery more than a decade ago, carbon nanotubes (CNTs) have held scientists and engineers in captive fascination, seated on the verge of enormous breakthroughs in areas such as medicine, electronics, and materials science, to name but a few. Taking a broad look at CNTs and the tools used to study them, Carbon Nanotubes: Properties and Applications comprises the efforts of leading nanotube researchers led by Michael O’Connell, protégé of the late father of nanotechnology, Richard Smalley. Each chapter is a self-contained treatise on various aspects of CNT synthesis, characterization, modification, and applications. The book opens with a general introduction to the basic characteristics and the history of CNTs, followed by discussions on synthesis methods and the growth of “peapod” structures. Coverage then moves to electronic properties and band structures of single-wall nanotubes (SWNTs), magnetic properties, Raman spectroscopy of electronic and chemical behavior, and electromechanical properties and applications in NEMS (nanoelectromechanical systems). Turning to applications, the final sections of the book explore mechanical properties of SWNTs spun into fibers, sidewall functionalization in composites, and using SWNTs as tips for scanning probe microscopes. Taking a fresh look at this burgeoning field, Carbon Nanotubes: Properties and Applications points the way toward making CNTs commercially viable.

Download or read book Carbon Nanotubes written by Jose Mauricio Marulanda and published by BoD – Books on Demand. This book was released on 2011-08-01 with total page 574 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes (CNTs), discovered in 1991, have been a subject of intensive research for a wide range of applications. In the past decades, although carbon nanotubes have undergone massive research, considering the success of silicon, it has, nonetheless, been difficult to appreciate the potential influence of carbon nanotubes in current technology. The main objective of this book is therefore to give a wide variety of possible applications of carbon nanotubes in many industries related to electron device technology. This should allow the user to better appreciate the potential of these innovating nanometer sized materials. Readers of this book should have a good background on electron devices and semiconductor device physics as this book presents excellent results on possible device applications of carbon nanotubes. This book begins with an analysis on fabrication techniques, followed by a study on current models, and it presents a significant amount of work on different devices and applications available to current technology.

Download or read book Industrial Applications of Carbon Nanotubes written by Huisheng Peng and published by William Andrew. This book was released on 2016-10-08 with total page 510 pages. Available in PDF, EPUB and Kindle. Book excerpt: Industrial Applications of Carbon Nanotubes covers the current applications of carbon nanotubes in various industry sectors, from the military to visual display products, and energy harvesting and storage. It also assesses the opportunities and challenges for increased commercialization and manufacturing of carbon nanotubes in the years ahead. Real-life case studies illustrate how carbon nanotubes are used in each industry sector covered, providing a valuable resource for scientists and engineers who are involved and/or interested in carbon nanotubes in both academia and industry. The book serves as a comprehensive guide to the varied uses of carbon nanotubes for specialists in many related fields, including chemistry, physics, biology, and textiles. - Explains how carbon nanotubes can be used to improve the efficiency and performance of industrial products - Includes real-life case studies to illustrate how carbon nanotubes have been successfully employed - Explores how carbon nanotubes could be mass-manufactured in the future, and outlines the challenges that need to be overcome

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 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 Carbon Nanotubes as a Pulsed Electron Sources written by Xianqi Wei and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the most promising applications of carbon nanotubes (CNTs) is the emission electronics, in which CNTs are used as a field emission electron source. Lots of electronic devices are based on electron sources, which are the most important components served as state-of-art nanoelectronics devices in nowadays, such as field emission displays, miniature mass spectrometers, scanning ultrafast electron microscopes, X-ray generators, free electron lasers, THz sources, and so on. Field electron emission is based on the physical phenomenon of quantum tunneling, in which electrons are emitted from the surface of materials into vacuum on the condition of applied voltage. CNTs have many advantages as field emitters comparing with conventional metallic emitters like familiar examples of tungsten, gold, copper, and molybdenum. Electron emission from cold cathodes of CNTs has attracted attentions of numerous scientists, and substantial researches have been conducted on their properties and applications. In this chapter, we will focus on the field emission of CNT cold cathodes as an electron source, including of how to synthesize it by chemical vapor deposition (CVD) method and how to realize its electron emission. In addition, we will report pulsed electron emission of CNT cathodes. The combination of the laser pulse and the cold cathode will offer the possibility of pulsed field emission. Our approach demonstrates the growth mechanism and the emission mechanism of CNTs, which is beneficial for controlling the performance of its fascinating application on emerging fields.