Download or read book The Effect of Catalyst Properties on the Synthesis of Carbon Nanotubes by Plasma Enhanced Chemical Vapor Deposition written by Surya Venkata Sekhar Cheemalapati and published by . This book was released on 2012 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study of the effect of catalyst properties on the synthesis of carbon nanotubes (CNTs) is done in this thesis. Three different metal alloy catalysts, Fe/Ti, Ni/Ti, Co/Ti, have been studied. Various atomic concentrations and thicknesses were cosputter deposited on clean Si wafers using AJA Orion 4 RF Magnetron sputter deposition tool at 5mtorr and 17°C, and the films were characterized using a scanning electron microscope, Energy-dispersive X-ray spectroscopy. All the alloys have been annealed at 650°C and 3 torr in an argon atmosphere at 100 SCCM, followed by ammonia gas plasma etch at different powers at 3 torr and 50 SCCM NH3 flow in a modified parallel plate RF chemical vapor deposition tool for 1 minute. The influence of plasma power, thickness of catalyst and concentration of Ti the secondary metal in the alloy composition, on the surface morphology of the catalyst are investigated by characterizing them with atomic force microscopy. The study has shown that the surface roughness is affected by Ti concentration, thickness and plasma power. The 35 W power NH3 plasma produced rougher surfaces when compared to the 75 W NH3 plasma. The result is interpreted as follows: ion bombardment leads to greater etching of the catalyst surface. Thus, plasma power must be optimized for catalyst thin film and etch time. The study has provided an in depth analysis and understanding of the various factors that influence catalyst surface morphology which can be applied into further study for optimizing parameters for synthesis of single walled CNTs. Following this, a study on catalysts for CNT synthesis was performed using Plasma enhanced chemical vapor deposition and characterized by scanning electron microscope. CNTs were synthesized on Ni, Ni-Ti, Co, Co-Ti and Fe catalyst. Ni, Ni-Ti catalyst produced forest like vertically aligned CNTs whereas Co, Co-Ti produced vertically aligned free standing CNTs. The growth was dense and uniform across the substrate. Initial growth runs on Fe, Fe-Ti alloy did not produce any CNTs until catalyst was restructured with a thicker Ti under layer after an investigation using Secondary ion mass spectrometry of suspected Fe catalyst poisoning due to reaction with Si substrate. A room temperature run was carried out on annealed and plasma etched Ni catalyst and no CNTs were produced indicating the importance of substrate temperature of CNTs. A deeper understanding of factors of influence on CNTs such as catalyst types, structure/morphology, and substrate temperature has been achieved with this study.
Download or read book Synthesis and Characterization of Carbon Nanotubes Using Plasma enhanced Chemical Vapor Deposition written by Wing Kwong Wong and published by . This book was released on 2004 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analysis and Performance of Engineering Materials written by Gennady E. Zaikov and published by CRC Press. This book was released on 2015-08-28 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt: This new book facilitates the study of problematic chemicals in such applications as chemical fate modeling, chemical process design, and experimental design. It provides a valuable overview of current chemical processes, products, and practices and analyzes theories to formulate and prove physicochemical principles. It addresses the production and
Download or read book Handbook of Nanomaterials Properties written by Bharat Bhushan and published by Springer Science & Business Media. This book was released on 2014-03-13 with total page 1467 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanomaterials attract tremendous attention in recent researches. Although extensive research has been done in this field it still lacks a comprehensive reference work that presents data on properties of different Nanomaterials. This Handbook of Nanomaterials Properties will be the first single reference work that brings together the various properties with wide breadth and scope.
Download or read book Electronic Properties of Carbon Nanotubes written by Jose Mauricio Marulanda and published by BoD – Books on Demand. This book was released on 2011-07-27 with total page 700 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. These one-dimensional (1D) graphene sheets rolled into a tubular form have been the target of many researchers around the world. This book concentrates on the semiconductor physics of carbon nanotubes, it brings unique insight into the phenomena encountered in the electronic structure when operating with carbon nanotubes. This book also presents to reader useful information on the fabrication and applications of these outstanding materials. The main objective of this book is to give in-depth understanding of the physics and electronic structure of carbon nanotubes. Readers of this book should have a strong background on physical electronics and semiconductor device physics. This book first discusses fabrication techniques followed by an analysis on the physical properties of carbon nanotubes, including density of states and electronic structures. Ultimately, the book pursues a significant amount of work in the industry applications of carbon nanotubes.
Download or read book Synthesis Technology and Applications of Carbon Nanomaterials written by Suraya Abdul Rashid and published by Elsevier. This book was released on 2018-10-10 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: Synthesis, Technology and Applications of Carbon Nanomaterials explores the chemical properties of different classes of carbon nanomaterials and their major applications. As carbon nanomaterials are used for a variety of applications due to their versatile properties and characteristics, this book discusses recent advances in synthesis methods, characterization, and applications of 0D -3D dimensional carbon nanomaterials. It is an essential resource for readers focusing on carbon nanomaterials research. - Explores the chemical properties of different classes of carbon nanomaterials and their major applications - Discusses recent advances in synthesis methods, characterization, and applications of 0D -3D dimensional carbon nanomaterials
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 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 Handbook of Nanomaterials for Industrial Applications written by Chaudhery Mustansar Hussain and published by Elsevier. This book was released on 2018-07-19 with total page 1143 pages. Available in PDF, EPUB and Kindle. Book excerpt: Handbook of Nanomaterials for Industrial Applications explores the use of novel nanomaterials in the industrial arena. The book covers nanomaterials and the techniques that can play vital roles in many industrial procedures, such as increasing sensitivity, magnifying precision and improving production limits. In addition, the book stresses that these approaches tend to provide green, sustainable solutions for industrial developments. Finally, the legal, economical and toxicity aspects of nanomaterials are covered in detail, making this is a comprehensive, important resource for anyone wanting to learn more about how nanomaterials are changing the way we create products in modern industry. - Demonstrates how cutting-edge developments in nanomaterials translate into real-world innovations in a range of industry sectors - Explores how using nanomaterials can help engineers to create innovative consumer products - Discusses the legal, economical and toxicity issues arising from the industrial applications of nanomaterials
Download or read book Carbon Nanotubes written by Ajay Kumar Mishra and published by Nova Science Publishers. This book was released on 2012-12 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes possess unusual fascinating properties which have attracted the scientific world. This book covers a very wide domain of research and development where the synthesis and properties of carbon nanotubes are discussed. This book describes the carbon nanotube general introduction, various synthesis procedures and properties. This book is going to be beneficial to the researchers who are working for their postgraduate degree in nanomaterials and nanotechnology. This book also provides a platform for all the academics and researchers as it covers a vast background for the recent literature, abbreviations, and summaries. This book will be worth reading for the researchers who are more interested in the general overview of carbon nanotubes, fundamentals concepts and various synthetic procedures in the multidisciplinary areas. This book contains the fundamental knowledge with the recent advancements for the research and development in the field of nanomaterials and nanotechnology.
Download or read book Physical Properties of Ceramic and Carbon Nanoscale Structures written by Stefano Bellucci and published by Springer Science & Business Media. This book was released on 2011-02-28 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the second volume in a series of books on selected topics in Nanoscale Science and Technology based on lectures given at the well-known INFN schools of the same name. The aim of this collection is to provide a reference corpus of suitable, introductory material to relevant subfields, as they mature over time, by gathering the significantly expanded and edited versions of tutorial lectures, given over the years by internationally known experts. The present set of notes stems in particular from the participation and dedication of prestigious lecturers, such as Andrzej Huczko, Nicola Pugno, Alexander Malesevic, Pasquale Onorato and Stefano Bellucci. All lectures were subsequently carefully edited and reworked, taking into account the extensive follow-up discussions. A tutorial lecture by Huczko et al. shows how a variety of carbon and ceramic nanostructures (nanotubes, nanowires, nanofibres, nanorods, and nanoencapsulates) have in particular great potential for improving our understanding of the fundamental concepts of the roles of both dimensionality and size on physical material properties . Bellucci and Onorato provide an extensive and tutorial review of the (quantum) transport properties in carbon nanotubes, encompassing a description of the electronic structure from graphene to single-wall nanotubes, as well as a discussion of experimental evidence of superconductivity in carbon nanotubes and the corresponding theoretical interpretation. In the first contribution by Pugno, new ideas on how to design futuristic self-cleaning, super-adhesive and releasable hierarchical smart materials are presented. He also reviews the mechanical strength of such nanotubes and megacables, with an eye to the visionary project of a carbon nanotube-based ‘space elevator megacable’. In his second contribution, Pugno outlines in detail the role on the fracture strength of thermodynamically unavoidable atomistic defects with different size and shape, both numerically and theoretically, for nanotubes and nanotube bundles. Focusing on graphitic allotropes, the chapter by Bellucci and Malesevic aims to give a taste of the widespread implications carbon nanostructures have on research and applications, starting from an historical overview, followed by a discussion of the structure and physical properties of carbon nanotubes and graphene, in particular in the context of the several different synthesis techniques presently available.
Download or read book Patterning and Characterization of Carbon Nanotubes Grown in a Microwave Plasma Enhanced Chemical Vapor Deposition Chamber written by Mauricio Kossler and published by . This book was released on 2009 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Syntheses and Applications of Carbon Nanotubes and Their Composites written by Satoru Suzuki and published by BoD – Books on Demand. This book was released on 2013-05-09 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes are rolled up graphene sheets with a quasi-one-dimensional structure of nanometer-scale diameter. In these last twenty years, carbon nanotubes have attracted much attention from physicists, chemists, material scientists, and electronic device engineers, because of their excellent structural, electronic, optical, chemical and mechanical properties. More recently, demand for innovative industrial applications of carbon nanotubes is increasing. This book covers recent research topics regarding syntheses techniques of carbon nanotubes and nanotube-based composites, and their applications. The chapters in this book will be helpful to many students, engineers and researchers working in the field of carbon nanotubes.
Download or read book Substrate and Catalyst Design for Chemical Vapor Deposition Synthesis of Carbon Nanotubes on Si Cu and SiC written by Ge Li and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis discussed the design of substrate and catalyst for chemical vapor deposition synthesis of carbon nanotubes (CNT). It was focused on synthesis CNTs on the various substrates, such as Si, Cu and SiC. The research was structured as following: (1) characterization of the Al2O3 buffer layer produced by plasma oxidation in order to find out the its effect on CNT growth; (2) study of the position parameters in CVD system to optimize process condition for manufacturing CNTs; (3) exploring novel composite catalyst alloys; (4) design new substrate for synthesis of vertically aligned CNTs on Cu and SiC for thermal application. Advanced surface analysis techniques were used to explore the role of AI2O3 supporting layer and of the composite catalyst. Although the data is insufficient for coming to a conclusion on the mechanism behind CNT super-growth, the preliminary studies provide guidance for selecting catalyst composite which will allow scaling up CNT production. A series of experiments using two CVD system (ET 1000 & ET 3000) were conducted which allowed for optimize the growth parameter and produce CNT arrays with uniform length. Vertically aligned CNTs arrays were successfully synthesized on copper and SiC substrates by adding supporting layers and adjusting the CVD growth conditions. This achievement engenders a wide range of future application in the field of thermal management.
Download or read book Synthesis of Carbon Nanotubes by Microwave Plasma Enhanced CVD on Silicon Using Iron as Catalyst written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nanocomposite Based Electronic Tongue written by Amin TermehYousefi and published by Springer. This book was released on 2017-10-24 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the fabrication of a frequency-based electronic tongue using a modified glassy carbon electrode (GCE), opening a new field of applying organic precursors to achieve nanostructure growth. It also presents a new approach to optimizing nanostructures by means of statistical analysis. The chemical vapor deposition (CVD) method was utilized to grow vertically aligned carbon nanotubes (CNTs) with various aspect ratios. To increase the graphitic ratio of synthesized CNTs, sequential experimental strategies based on response surface methodology were employed to investigate the crystallinity of CNTs. In the next step, glucose oxidase (GOx) was immobilized on the optimized multiwall carbon nanotubes/gelatin (MWCNTs/Gl) composite using the entrapment technique to achieve enzyme-catalyzed oxidation of glucose at anodic potentials, which was drop-casted onto the GCE. The modified GCE’s performance indicates that a GOx/MWCNTs/Gl/GC electrode can be utilized as a glucose biosensor with a high direct electron transfer rate between GOx and MWCNTs/Gl. It was possible to use the fabricated biosensor as an electronic tongue thanks to a frequency-based circuit attached to the electrochemical cell. The results indicate that the modified GCE (with GOx/MWCNTs/Gl) holds promising potential for application in voltammetric electronic tongues.
Download or read book Plasma Catalysis written by Annemie Bogaerts and published by MDPI. This book was released on 2019-04-02 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasma catalysis is gaining increasing interest for various gas conversion applications, such as CO2 conversion into value-added chemicals and fuels, N2 fixation for the synthesis of NH3 or NOx, methane conversion into higher hydrocarbons or oxygenates. It is also widely used for air pollution control (e.g., VOC remediation). Plasma catalysis allows thermodynamically difficult reactions to proceed at ambient pressure and temperature, due to activation of the gas molecules by energetic electrons created in the plasma. However, plasma is very reactive but not selective, and thus a catalyst is needed to improve the selectivity. In spite of the growing interest in plasma catalysis, the underlying mechanisms of the (possible) synergy between plasma and catalyst are not yet fully understood. Indeed, plasma catalysis is quite complicated, as the plasma will affect the catalyst and vice versa. Moreover, due to the reactive plasma environment, the most suitable catalysts will probably be different from thermal catalysts. More research is needed to better understand the plasma–catalyst interactions, in order to further improve the applications.
