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1、One-Dimensional NanomaterialsCarbon NanotubesReporter : Teammates: Wan jun Wu Yuanhe Wang Binbin Yang Yongzhu11423OutlineIntroductionStructure and PropertiesPreparationApplications22021/11/18 IntroductionSumio IijimaCarbon nanotubes (CNTs) was first discovered by Iijima in 199132021/11/18CNTs: rolli
2、ng up a thin graphene sheet. CNTsSWCNTs MWCNTs42021/11/18Production Methods1.Arc-discharge method 2.Laser Vaporization method3.Chemical Vapor Deposition (CVD)Preparation52021/11/18CVD methods have been successfully applied in making carbon nanotubes. The growth process with this method involves heat
3、ing a catalyst material to high temperatures in a tube furnace and flowing a hydrocarbon gas through the tube reactor for a period of time. Materials grown over the catalyst are collected upon cooling the system to room temperature. parameters: hydrocarbons, catalysts: such as transition-metal nanop
4、articles growth temperature. 62021/11/18Left diagram: base growth mode. Right diagram: tip growth modeCVD growth mechanism Process : Dissociation of hydrocarbon molecules catalyzed by the transition metal. Dissolution and saturation of carbon atoms in the metal nanoparticle. Precipitation of carbon
5、from the saturated metal particle leads to the formation of tubular carbon solids in sp2 structure. 72021/11/18Growth mechanism of a carbon nanotube at an open end by the absorption of C2 dimers and C3 trimers (in black), respectively The adsorption of a C2 dimer or a C3 trimer at the active danglin
6、g bond edge site will add one hexagon to the open end. Tubule formation is favored over other forms of carbon, because a tube contains no dangling bonds and therefore is in a low energy form.82021/11/18 Schematic experimental setups for other two nanotube growth methods92021/11/18Single-walled nanot
7、ubes grown by laser ablation102021/11/18Structure and Properties The uniqueness of the nanotube arises from its structure and the inherent subtlety in the structure, which is the helicity in the arrangement of the carbon atoms in hexagonal arrays on their surface honeycomb lattices. The helicity (lo
8、cal symmetry), along with the diameter (which determines the size of the repeating structural unit) introduces significant changes in the electronic density of states, and hence provides a unique electronic character for the nanotubes.112021/11/18CNTssuperior mechanical propertieslowmassdensityhighe
9、lectronmobilitylarge current-carrying capabilityhigh thermal conductivitylarge aspect ratio122021/11/18Wet SpinningAn aqueous suspension of carbon nanotubes, stabilized by a surfactant, is injected into a flowing solution of polyvinyl alcohol which causes the fiber to coagulate. It is then removed f
10、rom the bath and washed to remove excess polymer. Organization into Fibers132021/11/18Dry SpinningDry spinning from carbon nanotube forests. (a) A typical “forest” of multiwall carbon nanotubes grown from a substrate. (b) Photograph of the spinning of a carbon nanotube fiber from a forest of multiwa
11、ll nanotubes.142021/11/18(a) Picture of a SWNTs forest. (b) SEM image of the SWNTs forest ledge. (c) HRTEM image of SWNTs. (d) A large area TEM image. (e) SEM image of SWNT cylindrical pillars.Organization on Surfaces152021/11/18Vacuum Microelectronics: Electron field emission materials have been in
12、vestigated extensively for technological applications, such as flat panel displays, electron guns in electron microscopes, microwave amplifiers.Energy Storage: rechargeable lithium batteries, Hydrogen Storage.Filled Composites: reinforcements in high strength, light weight, high performance composit
13、es, such as spacecraft and aircraft body.Nanoprobes and Sensors: such as high resolution imaging, nano-lithography, nanoelectrodes, drug delivery, sensors and field emitters.Templates: fabricate one-dimensional nanowires.Applications162021/11/18Cathode-Ray Lighting ElementsDemonstration field emissi
14、on light source using carbon nanotubes as the cathodes172021/11/18Left: Schematic of a prototype field emission display using carbon nanotubes. field emission display fabricated by Samsung using carbon nanotubesFlat Panel Display182021/11/18 (c) Stress-strain relationship observed during the tension
15、/compression testing of the nanotube-epoxy composite (the curve that shows larger slope, both on the tension and compression sides of the stress-strain curve, belongs to the nanotube epoxy composite). It can be seen that the load transfer to the nanotube is higher during the compression cycle (seen
16、from the deviation of the composite curve from that of the pure epoxy), because in tension the individual layers of the nanotubes slide with respect to each other. 192021/11/18Results from the optical response of nanotube-doped polymers and theiruse in Organic Light Emitting Diodes (OLED) . The construction of the OLEDis shown in the schematic of (top). The bottom figure shows emission from OLEDstructures. Nanotube doping tunes the emission color. With SWNTs in the bufferlayer, holes are blocked
