材料结构及其性能英文

One-DimensionalNanomaterials

——CarbonNanotubesReporter:Teammates:Wan

jun

WuYuanhe

WangBinbin

YangYongzhu11423OutlineIntroductionStructureandPropertiesPreparationApplicationsIntroductionSumioIijimaCarbonnanotubes(CNTs)wasfirstdiscoveredbyIijimain1991CNTs:rollingupathingraphenesheet.CNTsSWCNTs

MWCNTsProductionMethods1.Arc-dischargemethod2.LaserVaporization

method3.ChemicalVaporDeposition(CVD)PreparationCVDmethodshavebeensuccessfullyappliedinmakingcarbonnanotubes.Thegrowthprocesswiththismethodinvolvesheatingacatalystmaterialtohightemperaturesinatubefurnaceandflowingahydrocarbongasthroughthetubereactorforaperiodoftime.Materialsgrownoverthecatalystarecollecteduponcoolingthesystemtoroomtemperature.parameters:

hydrocarbons,

catalysts:

suchas

transition-metalnanoparticles

growthtemperature.Leftdiagram:

basegrowthmode.

Rightdiagram:tipgrowth

modeCVDgrowthmechanismProcess

:

Dissociationofhydrocarbonmoleculescatalyzedbythetransitionmetal.Dissolutionandsaturationofcarbon

atomsinthemetalnanoparticle.

Precipitationofcarbonfromthesaturatedmetalparticleleadstotheformationoftubularcarbonsolidsinsp2structure.GrowthmechanismofacarbonnanotubeatanopenendbytheabsorptionofC2dimersandC3trimers(inblack),

respectivelyTheadsorptionofaC2dimeroraC3trimer

attheactivedanglingbondedgesitewilladdonehexagontotheopenend.

Tubuleformationisfavoredoverotherformsofcarbon,becauseatube

containsnodangling

bondsandthereforeisinalowenergy

form.Schematicexperimental

setupsforothertwonanotube

growthmethodsSingle-walled

nanotubesgrownbylaser

ablationStructureandProperties

Theuniquenessofthenanotubearisesfromitsstructureandtheinherentsubtletyinthestructure,whichisthehelicityinthearrangementofthecarbonatomsinhexagonalarraysontheirsurfacehoneycomblattices.

Thehelicity(localsymmetry),alongwiththediameter(whichdeterminesthesizeoftherepeatingstructuralunit)introducessignificantchangesintheelectronicdensityofstates,andhenceprovidesauniqueelectroniccharacterforthenanotubes.CNTssuperiormechanicalpropertieslowmassdensityhighelectronmobilitylargecurrent-carryingcapabilityhighthermalconductivitylargeaspectratioWetSpinningAn

aqueoussuspensionofcarbonnanotubes,

stabilizedbyasurfactant,isinjectedintoa

flowingsolutionofpolyvinylalcoholwhich

causesthefibertocoagulate.Itisthenremoved

fromthebathandwashedtoremove

excesspolymer.OrganizationintoFibersDrySpinningDryspinningfromcarbonnanotubeforests.(a)Atypical“forest”ofmultiwall

carbonnanotubesgrownfromasubstrate.(b)Photograph

ofthespinningofacarbonnanotubefiberfromaforestofmultiwallnanotubes.(a)PictureofaSWNTsforest.(b)SEMimageoftheSWNTsforestledge.(c)HRTEMimageofSWNTs.(d)Alarge

area

TEMimage.(e)SEMimageofSWNTcylindricalpillars.OrganizationonSurfacesVacuumMicroelectronics:

Electronfieldemissionmaterialshavebeeninvestigatedextensivelyfortechnologicalapplications,suchasflatpaneldisplays,electrongunsinelectronmicroscopes,microwaveamplifiers.EnergyStorage:rechargeablelithiumbatteries,HydrogenStorage.FilledComposites:reinforcementsinhighstrength,lightweight,highperformancecomposites,suchasspacecraftandaircraftbody.NanoprobesandSensors:suchashighresolutionimaging,nano-lithography,nanoelectrodes,drugdelivery,sensorsandfieldemitters.Templates:fabricateone-dimensionalnanowires.ApplicationsCathode-RayLightingElementsDemonstrationfieldemissionlightsourceusingcarbonnanotubesasthe

cathodesLeft:Schematicofaprototypefieldemissiondisplayusingcarbonnanotubes.Right:Aprototype4.5''fieldemissiondisplayfabricatedby

SamsungusingcarbonnanotubesFlatPanelDisplay(c)Stress-strainrelationship

observedduringthetension/compressiontestingofthenanotube-epoxy

composite(thecurvethatshowslargerslope,bothonthetension

andcompressionsidesofthestress-straincurve,belongstothenanotubeepoxy

composite).Itcanbeseenthattheloadtransfertothenanotubeishigherduring

thecompressioncycle(seenfromthedeviationofthecompositecurvefromthat

ofthepureepoxy),becauseintensiontheindividuallayersofthenanotubesslide

withrespecttoeachother.Resultsfromtheopticalresponseofnanotube-dopedpolymersandtheiruseinOrganicLightEmittingDiodes(OLED).TheconstructionoftheOLEDisshownintheschematicof(top).ThebottomfigureshowsemissionfromOLEDstructures.Nanotubedopingtunestheemissioncolor.WithSWNTsinthebufferlayer,holesareblockedandrecombinationtakesplaceinthetransportlayerandtheemissioncolorisred.Withoutnanotubespresentinthebufferlayer,theemissioncolorisgreen.Use洪of感a慨MWN宵Ta程sa记nA济FM唱tip咐.A荐tt况he砌cen喊ter鞭of班th膏eVap脖or搬Gro弓wn宣Car读bon看Fi键ber卡(V勉GCF停)i碗sa量MW老NT池whi忽ch轻for剂ms踩the许ti拣p.她TheVGC只Fp溜rov填ide热sa龟co映nve规nie禾nt损and炉ro截bus价tt溪ech见niq道ue庭for语mo美unt礼ing号th秋eM酿WNT以pr泻obefor指us衰ei垒na轮sc保ann请ing凑pr谣obe捏in线str声ume春ntMWC堡NTsast焰empl歪ates起.Th则ele馅ft-h锡and屈figu谁reisa桌sch沟emat寄ict蛛hat燃show躁sth泄efi边llin交gof尾the湾emp括tyo首ne-d船imen茶sion臂alh多ollo吼wco巩reo宜fnano升tube值swi型thf抽orei环gns针ubst躬ance党s.(伤a)S低hows俩aHRTEM液ima