Download or read book Synthesis of One dimensional Boron Related Nanostructures by Chemical Vapor Deposition written by Li Guo and published by . This book was released on 2008 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt: Motivated by the extensive research on carbon nanotubes (CNTs), boron and its related nano-structures have attracted increasing interest for potential applications in nanodevices and nanotechnologies, due to their extraordinary properties. In this work, different types of B-related nanostructures were successfully grown on oxidized Si substrates with or without transition metal catalysts in CVD processes. The gas chemistry was monitored by in-situ mass-spectroscopy and optical emission spectroscopy. These helped to identify the gas reactive species during the deposition, creating thereby a controllable, optimum synthesis process and helping in identifying the growth mechanism. The boron nitride nanotubes (BNNTs) were successfully synthesized at the low substrate temperatures of 600-800oC by a microwave plasma CVD process, using diborane and ammonia as the gas precursors. The optimum growth conditions of BNNTs were investigated by varying the experimental parameters, such as catalyst film thickness, substrate temperature, diborane flow rate, and growth time. The dense and crystalline BNNT deposits were obtained on 1nm nickel (Ni) or cobalt (Co) thin film coated oxidized Si (111) at a temperature of 800oC, a pressure of 15 torr, microwave power of 800 W, diborane flow rate (5 vol.% in hydrogen) of 5 sccm, ammonia flow rate of 27.5 sccm, hydrogen flow rate of 10sccm, and a deposition time of 1 hour. These nanotubes were either self-assembled in bundles or as a single tube with a diameter less than 10 nm. Raman spectra together with electron diffraction pattern indicated a hexagonal crystalline structure for these BN nanostructures. A growth mechanism of BNNTs involving dissolution-supersaturation- precipitation of BN in the metal catalysts was proposed. It was shown that the growth of BN nanostructures strongly depended on the catalyst and its film thickness, which resulted in the selective growth of BNNTs on the patterned catalyst islands. Ni dots with the diameters in the submicron range were used to synthesize aligned BNNTs. Fine BN nanostructures with a diameter around 10-20 nm and length up to 10 microns were grown and dispersed in the Ni dots. Nanosized Ni dots were suggested for the growth of the vertically aligned BNNTs. Boron nanowires (BNWs) were also grown by the decomposition of diborane using a thermal CVD process at a temperature of 900oC, a pressure of 20 torr, diborane flow rate (5 vol.% in hydrogen) of 5 sccm, and nitrogen flow rate of 55 sccm. These BNWs had diameters in a range of 20-200 nanometers and lengths up to several tens of micrometers. Repeatable Raman spectra indicated icosahedra B12 to be the basic building units forming the B nanowires. Amorphous BNWs with rough surface were obtained without any catalysts on different substrates, such as Si wafer or ZrB2 powders. A vapor-solid (VS) growth was proposed for the amorphous BNWs, in which the solid phase precipitated directly from the vapor phase reactions. The amorphous BNWs were modified for size and composition using a plasma CVD process containing argon, ammonia and hydrogen. The diameters of these BNWs were reduced from 200 nm to several tens of nanometers, and a small amount of N was incorporated into BNWs after the plasma treatment. On the other hand, the metal catalyst proved to be effective for the growth of crystalline BNWs. Tetragonal BNWs with smooth surface were grown on thin Ni film (1 nm) coated Si substrates. Ni attachment was observed at the tip of the BNW for the first time, which indicated that the vapor-liquid-solid (VLS) growth mechanism can be used for synthesis of the BNW. The diameters of these BNWs were strongly dependent on the size of the metal particles encapsulated in the BNWs. In summary, two boron-related nanostructures were synthesized by chemical vapor deposition (CVD) in this work. A new method was successfully developed to decrease the substrate temperature more than 400oC to fabricate boron nitride nanotubes in a microwave plasma enhanced chemical vapor deposition process using gas reactions of diborane and ammonia. The catalytic growth of BNNTs done in this work provided a novel way to selectively grow BNNTs in thin film form on Ni or Co coated Si substrates. For boron nanowires, the co-existence of two growth mechanisms was discovered having completely different morphology and crystallinity using the thermal CVD process. The metal catalyst assisted the growth of the crystalline BNWs by vapor-liquid-solid mechanism, which amorphous BNWs were produced without the use of the catalyst. These results are expected to open up more pathways to scale up the fabrication of vertically aligned BNNTs and BNWs for studies of their properties and applications.

Download or read book Chemical Vapor Deposition Growth and Characterization of Two Dimensional Hexagonal Boron Nitride written by Roland Yingjie Tay and published by Springer. This book was released on 2018-06-30 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis focuses on the growth of a new type of two-dimensional (2D) material known as hexagonal boron nitride (h-BN) using chemical vapor deposition (CVD). It also presents several significant breakthroughs in the authors’ understanding of the growth mechanism and development of new growth techniques, which are now well known in the field. Of particular importance is the pioneering work showing experimental proof that 2D crystals of h-BN can indeed be hexagonal in shape. This came as a major surprise to many working in the 2D field, as it had been generally assumed that hexagonal-shaped h-BN was impossible due to energy dynamics. Beyond growth, the thesis also reports on synthesis techniques that are geared toward commercial applications. Large-area aligned growth and up to an eightfold reduction in the cost of h-BN production are demonstrated. At present, all other 2D materials generally use h-BN as their dielectric layer and for encapsulation. As such, this thesis lays the cornerstone for using CVD 2D h-BN for this purpose.

Download or read book Single Layer Nanomaterials written by Ashley L Gibb and published by . This book was released on 2015 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: The design of novel nanomaterials with tunable geometries and properties has transformed chemistry and physics in recent years. In particular, recent advances in the isolation of two-dimensional films have inspired the exploration and development of stable, self-supporting single layer systems. Most notably graphene, a single layer of hexagonal sp2 carbon, has attracted interest due to intriguing electronic, optical, and mechanical properties. Hexagonal boron nitride (h-BN) is a closely related two- dimensional material, isoelectronic with graphene but often exhibiting very different electronic characteristics. The production of these monolayer materials has revealed exciting new properties that arise due to constrained geometry at the nanoscale. This dissertation explores the atomic scale properties of low-dimensional hexagonal nanomaterials, with a particular focus on hexagonal boron nitride (h-BN), graphene, and related materials. The synthesis processes for hexagonal boron nitride, graphene, nanotubes and nanoribbons will be discussed, with a particular emphasis on chemical vapor deposition. By controlling the number of layers in two-dimensional materials, we can tune their properties for new applications. The fabrication, characterization, and functionalization of additional low-dimensional nanomaterials including nanoribbons, nanotubes, and the composite materials that contain them will also be introduced. In nanoscale systems, material properties are heavily influenced by atomic structure and defects. This dissertation will discuss the investigation of h-BN and graphene at the atomic scale, with a particular emphasis on defects studied by atomic resolution transmission electron microscopy. Further probing the dynamics of these atomic defects includes in situ imaging and heating from room temperature up to 1000°C. Under these extreme conditions, novel defect structures and dynamics have been observed. In the coming years, these materials will continue to revolutionize the way we think about nanoscale materials, and are likely to be implemented into a variety of new and emerging technologies.

Download or read book Synthesis and Characterization of Boron Nitride Nanostructures Produced by Laser Chemical Vapor Deposition written by Arturo Hidalgo Córdova and published by . This book was released on 2012 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis Characterization and Fabrication of Boron Nitride and Carbon Nanomaterials Their Applications and the Extended Pressure Inductively Coupled Plasma Synthesis of Boron Nitride Nanotubes written by Aidin Fathalizadeh and published by . This book was released on 2016 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoscale materials made of carbon, boron, and nitrogen, namely BCN nanostructures, exhibit many remarkable properties making them uniquely suitable for a host of applications. Boron nitride (BN) and carbon (C) nanomaterials are structurally similar. The forms studied here originate from a two-dimensional hexagonally arranged structure of sp2 bonded atoms. These nanomaterials exhibit extraordinary mechanical and thermal properties. However, the unique chemical compositions of carbon and boron nitride result in differing electrical, chemical, biological, and optical properties. In this work, we explore the single layer sheets of sp2 bonded carbon (graphene), and their cylindrical forms (nanotubes) of carbon and boron nitride. In the first part of this work, we look at carbon based nanomaterials. In Chapter 2, the electron field emission properties of carbon nanotubes (CNTs) and their implementation as nanoelectromechanical oscillators in an integrated device will be discussed. We show a technique hereby a single CNT is attached to a probe tip and its electron field emission characterized. We then delve into the fabrication of a field emitting CNT oscillator based integrated device using a silicon nitride membrane support. We then present the electron field emission capabilities of these devices and discuss their potential use for detection of nuclear magnetic resonance (NMR) signals. Graphene is the subject of study in Chapter 3. We begin by extensively examining the synthesis of graphene using a chemical vapor deposition (CVD) process, ultimately establishing techniques to control graphene domain size, shape, and number of layers. We then discuss the application of the single-atom thick, but ultra-mechanically strong graphene as a capping layer to trap solutions in a custom fabricated silicon nitride membrane to enable transmission electron microscopy (TEM) of liquid environments. In this manner, the volume and position of liquid cells for electron microscopy can be precisely controlled and enable atomic resolution of encapsulated particles. In the second portion of this work, we investigate boron nitride nanostructures and in particular nanotubes. In Chapter 4, we present the successful development and operation of a high-throughput, scalable BN nanostructures synthesis process whereby precursor materials are directly and continuously injected into a novel high-temperature, Extended-Pressure Inductively-Coupled plasma system (EPIC). The system can be operated in a near-continuous fashion and has a record output of over 35 g/hour for pure, highly crystalline boron nitride nanotubes (BNNTs). We also report the results of numerous runs exploring the wide range of operating parameters capable with the EPIC system. In Chapter 5, we examine the impurities present in as-synthesized BNNT materials. Several methods of sample purification are then investigated. These include chemical oxidation, using both gas and liquid phase based methods, as well as physical separation techniques. The large scale synthesis of BNNTs has opened the door for further studies and applications. In Chapter 6, we report a novel wet-chemistry based route to fill in the inner cores of BNNTs with metals. For the first time, various metals are loaded inside of BNNTs, forming a plethora of structures (such as rods, short nanocrystals, and nanowires), using a solution-based method. We are also able to initiate and observe dynamics of the metallic nanoparticles, including their movement, splitting, and fusing, within a BNNT.

Download or read book Two dimensional Materials written by Pramoda Kumar Nayak and published by BoD – Books on Demand. This book was released on 2016-08-31 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: There are only a few discoveries and new technologies in materials science that have the potential to dramatically alter and revolutionize our material world. Discovery of two-dimensional (2D) materials, the thinnest form of materials to ever occur in nature, is one of them. After isolation of graphene from graphite in 2004, a whole other class of atomically thin materials, dominated by surface effects and showing completely unexpected and extraordinary properties, has been created. This book provides a comprehensive view and state-of-the-art knowledge about 2D materials such as graphene, hexagonal boron nitride (h-BN), transition metal dichalcogenides (TMD) and so on. It consists of 11 chapters contributed by a team of experts in this exciting field and provides latest synthesis techniques of 2D materials, characterization and their potential applications in energy conservation, electronics, optoelectronics and biotechnology.

Download or read book Synthesis and Characterization of Boron Based One dimensional Nanostructures written by Yan Li and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Boric acid (H3BO3) nanotubes, nanotips, nanorods, microtubes, and microtips were synthesized by exposing a thin film containing boron, carbon, and oxygen to a controllable humid atmosphere. X-ray photoelectron spectroscopy (XPS) and Secondary ion mass spectrometry (SIMS) were used to characterize the thin films. The boric acid structures were studied by X-ray diffraction (XRD), Scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAD), and electron energy-loss spectrometry (EELS). The growth process of the boric acid structures was investigated. The dehydration kinetics of boric acid nanostructures in a vacuum was explored.

Download or read book Quantum Dots for Quantum Information Technologies written by Peter Michler and published by Springer. This book was released on 2017-06-01 with total page 457 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights the most recent developments in quantum dot spin physics and the generation of deterministic superior non-classical light states with quantum dots. In particular, it addresses single quantum dot spin manipulation, spin-photon entanglement and the generation of single-photon and entangled photon pair states with nearly ideal properties. The role of semiconductor microcavities, nanophotonic interfaces as well as quantum photonic integrated circuits is emphasized. The latest theoretical and experimental studies of phonon-dressed light matter interaction, single-dot lasing and resonance fluorescence in QD cavity systems are also provided. The book is written by the leading experts in the field.

Download or read book Micro Chemical Vapor Deposition for the Synthesis of Nanomaterials written by Qin Zhou and published by . This book was released on 2011 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: MEMS (Microelectromechanical Systems) technologies have enabled the construction of a micro chemical vapor deposition (μCVD) system for the synthesis of nanomaterials. By means of localized resistive heating via micro-heaters, unique capabilities of the μCVD systems have been utilized to synthesize carbon nanotubes and graphene in this work, including fast stabilization of temperature; rapid exchange of gas species; laminar gas flow due to small Reynolds number; small diffusion length; and enhanced mass transport. In the prototype designs, the μCVD system is composed of a suspended microheater and two contact pads constructed from the device layer of a SOI (silicon-on-insulator) substrate. Both heat transfer and fluidic analyses have been conducted to validate and optimize the key features of the system. Experimental results in the synthesis of single-walled carbon nanotubes (SWNTs) have shown that amorphous carbon formation can be deterred and ultra-long SWNTs can be grown using ethylene as the source gas using μCVD system while similar experimental conditions failed to produce SWNTs in a conventional CVD system. Further applications of the μCVD system have been successfully demonstrated, including direct placement of high-quality, well-aligned SWNTs on temperature sensitive substrates such as thin paper or polymer sheets, and the synthesis of two-dimensional crystalline graphene structure with good uniformity. Specifically, the construction of high-performance CNT-based devices requires high-quality CNTs while conventional transfer and assembly processes often alter and degrade their properties. The localized heating of μCVD allows the direct synthesis of self-aligned SWNTs onto flexible substrates without causing thermal damages. Both Raman spectral and transmission electron microscopy have been used to validate the quality of these SWNTs. This methodology of direct synthesis of nanomaterials could be applicable to other one-dimensional nanostructures for various applications including flexible electronics. In the application to graphene growth, large area graphene with consistent number of layers has been realized on top of a nickel-coated micro platform using the μCVD system. The capability of ultra-fast heating and cooling provided by the MEMS platform is crucial for the successful growth of graphene. In the prototype graphene synthesis experiments, methane is flowed at 1.5% volume ratio with hydrogen to the platform heated to 1000oC and the heating power is cut off after a 5-min growth process. It has been demonstrated that 12̃ layers of graphene structures can be consistently grown throughout the whole 300×300 m2 platform.

Download or read book Synthesis and Characterization of Boron based One dimensional Nanostructures written by Carolyn Jones Otten and published by . This book was released on 2004 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Applications of One and Two Dimensional Boron Nitride Based Nanomaterials written by and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : One and two-dimensional hexagonal boron nitride (h-BN) nanomaterials are wide bandgap semiconductors (~6 eV). This large bandgap is in contrast with their corresponding carbon counterparts, for instance, graphene is metallic while carbon nanotubes are semiconducting or metallic depending upon their tube diameter and chirality. The insulating nature of boron nitride nanotubes (BNNTs) has hindered their application in the electronic field despite the superior physical and chemical properties. Our results have shown that BNNTs functionalized with metallic quantum dots have shown their potential as a tunneling field effect transistors (TFETs) devices. Moreover, BNNTs functionalized with carbon nanotubes (CNTs), and molecular carbon has shown potential as digital switches. In this dissertation, methods of functionalizing BNNTs by metallic quantum dots and carbon nanomaterials are discussed. Furthermore, synthesis of other h-BN nanomaterials has been explored. Using the well-established chemical vapor deposition technique, boron nitride nanosheets (BNNSs) and boron nitride nanoribbons (BNNRs) have been synthesized. Towards the end, an outlook on the synthesis of boron nanomaterial is provided.

Download or read book One Dimensional Nanostructures written by Tianyou Zhai and published by John Wiley & Sons. This book was released on 2012-10-19 with total page 857 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reviews the latest research breakthroughs and applications Since the discovery of carbon nanotubes in 1991, one-dimensional nanostructures have been at the forefront of nanotechnology research, promising to provide the building blocks for a new generation of nanoscale electronic and optoelectronic devices. With contributions from 68 leading international experts, this book reviews both the underlying principles as well as the latest discoveries and applications in the field, presenting the state of the technology. Readers will find expert coverage of all major classes of one-dimensional nanostructures, including carbon nanotubes, semiconductor nanowires, organic molecule nanostructures, polymer nanofibers, peptide nanostructures, and supramolecular nanostructures. Moreover, the book offers unique insights into the future of one-dimensional nanostructures, with expert forecasts of new research breakthroughs and applications. One-Dimensional Nanostructures collects and analyzes a wealth of key research findings and applications, with detailed coverage of: Synthesis Properties Energy applications Photonics and optoelectronics applications Sensing, plasmonics, electronics, and biosciences applications Practical case studies demonstrate how the latest applications work. Tables throughout the book summarize key information, and diagrams enable readers to grasp complex concepts and designs. References at the end of each chapter serve as a gateway to the literature in the field. With its clear explanations of the underlying principles of one-dimensional nanostructures, this book is ideal for students, researchers, and academics in chemistry, physics, materials science, and engineering. Moreover, One-Dimensional Nanostructures will help readers advance their own investigations in order to develop the next generation of applications.

Download or read book Synthesis and Properties of Boron Nitride written by J.J. Pouch and published by Trans Tech Publications Ltd. This book was released on 1991-01-01 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt: Boron nitride thin films can be deposited on different substrates using techniques such as plasma deposition, ion beam deposition and reactive sputter deposition.

Download or read book Handbook of Boron Nanostructures written by Sumit Saxena and published by CRC Press. This book was released on 2016-04-27 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: The phenomenal success of nanostructures in various applications has led to the exploration of a plethora of novel nanomaterials. Nanoboron is no exception. Boron as material has the ability to form covalently bonded stable networks and finds use in a large variety of applications. This book provides a complete overview of the latest developments i

Download or read book Boron Nitride written by Eugene Moran and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A hexagonal boron nitride nanosheet (BNNS) is an atomic-thick 2D material that exhibits many interesting properties such as high chemical stability and excellent mechanical and thermal properties. In Chapter One, the authors introduce two methods for the exfoliation of BNNS from hexagonal boron nitride (hBN). Then, methodologies for the surface functionalisation and nanocomposite construction are demonstrated by two BNNS based nanocomposites. The catalytic performance of the BNNS based nanocomposites is also evaluated and discussed in detail. Chapter two evaluates the formation of rolled hexagonal boron nitride nano-sheets (h-BN nanoscrolls) on their unique morphology, magnetic properties and applications. Due to the high chemical and thermal stabilities, as well as atomically smooth surfaces with free of dangling bonds, hBN has been used as barriers, passivation and support layers in 2D electronic devices, to maximise the electrical and optical characterisation of 2D materials. However, there still remains a challenge in obtaining large-area and high-quality hBN film for real 2D electronic devices. Chapter Three focuses on chemical vapor deposition (CVD), a promising method to overcome these limitations. Chapter Four discusses how a boron doped armchair graphene ribbon has been shown by cyclic voltammetry to be a potential catalyst to replace platinum, however the reaction catalysed was not identified. The authors use density functional calculations to show the reaction catalysed is likely dissociation of HO2. Chapter Five reveals a novel and industrially feasible route to incorporate boron nitride nanoparticles (BNNPs) in radiation-shielding aerospace structural materials. Chapter Six deals with the preparation and characterisation of boron nitride nanotube (BNNT)-reinforced biopolyester matrices. The morphology, hydrophilicity, biodegradability, cytotoxicity, thermal, mechanical, tribological and antibacterial properties of the resulting nanocomposites are discussed in detail. Chapter Seven presents theoretical estimations regarding the compressive buckling response of single walled boron nitride nanotubes (SWBNNTs), which have a similar crystal structure as single walled carbon nanotubes (SWCNTs). Moreover, SWBNNTs have excellent mechanical, insulating and dielectric properties. Finally, Chapter Eight shows how the different exchange mechanisms can be distinguished and measured by studying solid films where part of the 3He is replaced by immobile Ne atoms. The authors also show how the formation energy of vacancies and vacancy tunneling frequency can be obtained from NMR studies at high temperature.

Download or read book Chemical Vapor Deposition of One Dimensional Tin Oxide Nanostructures written by Jun Pan and published by . This book was released on 2010 with total page 211 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Layered 2D Materials and Their Allied Applications written by Inamuddin and published by John Wiley & Sons. This book was released on 2020-04-27 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ever since the discovery of graphene, two-dimensional layered materials (2DLMs) have been the central tool of the materials research community. The reason behind their importance is their superlative and unique electronic, optical, physical, chemical and mechanical properties in layered form rather than in bulk form. The 2DLMs have been applied to electronics, catalysis, energy, environment, and biomedical applications. The following topics are discussed in the book’s fifteen chapters: • The research status of the 2D metal-organic frameworks and the different techniques used to synthesize them. • 2D black phosphorus (BP) and its practical application in various fields. • Reviews the synthesis methods of MXenes and provides a detailed discussion of their structural characterization and physical, electrochemical and optical properties, as well as applications in catalysis, energy storage, environmental management, biomedicine, and gas sensing. • The carbon-based materials and their potential applications via the photocatalytic process using visible light irradiation. • 2D materials like graphene, TMDCs, few-layer phosphorene, MXene in layered form and their heterostructures. • The structure and applications of 2D perovskites. • The physical parameters of pristine layered materials, ZnO, transition metal dichalcogenides, and heterostructures of layered materials are discussed. • The coupling of graphitic carbon nitride with various metal sulfides and oxides to form efficient heterojunction for water purification. • The structural features, synthetic methods, properties, and different applications and properties of 2D zeolites. • The methods for synthesizing 2D hollow nanostructures are featured and their structural aspects and potential in medical and non-medical applications. • The characteristics and structural aspects of 2D layered double hydroxides (LDHs) and the various synthesis methods and role of LDH in non-medical applications as adsorbent, sensor, catalyst, etc. • The synthesis of graphene-based 2D layered materials synthesized by using top-down and bottom-up approaches where the main emphasis is on the hot-filament thermal chemical vapor deposition (HFTCVD) method. • The different properties of 2D h-BN and borophene and the various methods being used for the synthesis of 2D h-BN, along with their growth mechanism and transfer techniques. • The physical properties and current progress of various transition metal dichalcogenides (TMDC) based on photoactive materials for photoelectrochemical (PEC) hydrogen evolution reaction. • The state-of-the-art of 2D layered materials and associated devices, such as electronic, biosensing, optoelectronic, and energy storage applications.