中原工学院材料与化工学院专业英语翻译作业

CarbonnanotubeCarbonnanotubes(CNTs)areHYPERLINK"http://en.wikipedia.org/wiki/Allotropes_of_carbon"allotropesofcarbonwithaHYPERLINK"http://en.wikipedia.org/wiki/Cylindrical"cylindricalHYPERLINK"http://en.wikipedia.org/wiki/Nanostructure"nanostructure.Nanotubeshavebeenconstructedwithlength-to-diameterratioofupto132,000,000:1,HYPERLINK\l"cite_note-Longest-1"[1]significantlylargerthanforanyothermaterial.ThesecylindricalHYPERLINK"http://en.wikipedia.org/wiki/Carbon"carbonHYPERLINK"http://en.wikipedia.org/wiki/Molecule"moleculeshaveunusualproperties,whicharevaluableforHYPERLINK"http://en.wikipedia.org/wiki/Nanotechnology"nanotechnology,HYPERLINK"http://en.wikipedia.org/wiki/Electronics"electronics,HYPERLINK"http://en.wikipedia.org/wiki/Optics"opticsandotherfieldsofHYPERLINK"http://en.wikipedia.org/wiki/Materials_science"materialsscienceandtechnology.Inparticular,owingtotheirextraordinaryHYPERLINK"http://en.wikipedia.org/wiki/Thermal_conductivity"thermalconductivityandmechanicalandHYPERLINK"http://en.wikipedia.org/wiki/Electricity"electricalproperties,carbonnanotubesfindapplicationsasadditivestovariousstructuralmaterials.Forinstance,nanotubesformatinyportionofthematerial(s)insome(primarilyHYPERLINK"http://en.wikipedia.org/wiki/Carbon_fiber"carbonfiber)baseballbats,golfclubs,orcarparts.HYPERLINK\l"cite_note-2"[2]NanotubesaremembersoftheHYPERLINK"http://en.wikipedia.org/wiki/Fullerene"fullerenestructuralfamily.Theirnameisderivedfromtheirlong,hollowstructurewiththewallsformedbyone-atom-thicksheetsofcarbon,calledHYPERLINK"http://en.wikipedia.org/wiki/Graphene"graphene.Thesesheetsarerolledatspecificanddiscrete("HYPERLINK"http://en.wikipedia.org/wiki/Chirality"chiral")angles,andthecombinationoftherollingangleandradiusdecidesthenanotubeproperties;forexample,whethertheindividualnanotubeshellisaHYPERLINK"http://en.wikipedia.org/wiki/Metal"metalorHYPERLINK"http://en.wikipedia.org/wiki/Semiconductor"semiconductor.NanotubesarecategorizedasHYPERLINK\l"Single-walled"single-wallednanotubes(SWNTs)andHYPERLINK\l"Multi-walled"multi-wallednanotubes(MWNTs).Individualnanotubesnaturallyalignthemselvesinto"ropes"heldtogetherbyHYPERLINK"http://en.wikipedia.org/wiki/Van_der_Waals_force"vanderWaalsforces,morespecifically,pi-stacking.AppliedHYPERLINK"http://en.wikipedia.org/wiki/Quantum_chemistry"quantumchemistry,specifically,HYPERLINK"http://en.wikipedia.org/wiki/Orbital_hybridization"orbitalhybridizationbestdescribeschemicalbondinginnanotubes.TheHYPERLINK"http://en.wikipedia.org/wiki/Chemical_bonding"chemicalbondingofnanotubesiscomposedentirelyofHYPERLINK"http://en.wikipedia.org/wiki/Sp2_bond"sp2bonds,similartothoseofHYPERLINK"http://en.wikipedia.org/wiki/Graphite"graphite.Thesebonds,whicharestrongerthantheHYPERLINK"http://en.wikipedia.org/wiki/Sp3_bond"sp3bondsfoundinHYPERLINK"http://en.wikipedia.org/wiki/Alkane"alkanesandHYPERLINK"http://en.wikipedia.org/wiki/Diamond"diamond,providenanotubeswiththeiruniquestrength.TerminologyThereisnoconsensusonsometermsdescribingcarbonnanotubesinscientificliterature:both"-wall"and"-walled"arebeingusedincombinationwith"single","double","triple"or"multi",andtheletterCisoftenomittedintheabbreviation;forexample,multi-walledcarbonnanotube(MWNT).Single-walledMostsingle-wallednanotubes(SWNT)haveadiameterofcloseto1nanometer,withatubelengththatcanbemanymillionsoftimeslonger.ThestructureofaSWNTcanbeconceptualizedbywrappingaone-atom-thicklayerofgraphitecalledgrapheneintoaseamlesscylinder.Thewaythegraphenesheetiswrappedisrepresentedbyapairofindices(n,m).TheintegersnandmdenotethenumberofunitHYPERLINK"http://en.wikipedia.org/wiki/Vector_(geometric)"vectorsalongtwodirectionsinthehoneycombHYPERLINK"http://en.wikipedia.org/wiki/Crystal_lattice"crystallatticeofgraphene.Ifm=0,thenanotubesarecalledzigzagnanotubes,andifn=m,thenanotubesarecalledarmchairnanotubes.Otherwise,theyarecalledchiral.Thediameterofanidealnanotubecanbecalculatedfromits(n,m)indicesasfollowswherea=0.246nm.SWNTsareanimportantvarietyofcarbonnanotubebecausemostoftheirpropertieschangesignificantlywiththe(n,m)values,andthisdependenceisnon-monotonic(seeHYPERLINK"http://en.wikipedia.org/wiki/Optical_properties_of_carbon_nanotubes#Kataura_plot"Katauraplot).Inparticular,theirHYPERLINK"http://en.wikipedia.org/wiki/Band_gap"bandgapcanvaryfromzerotoabout2eVandtheirelectricalconductivitycanshowmetallicorsemiconductingbehavior.Single-wallednanotubesarelikelycandidatesforminiaturizingelectronics.Themostbasicbuildingblockofthesesystemsistheelectricwire,andSWNTswithdiametersofanorderofananometercanbeexcellentconductors.HYPERLINK\l"cite_note-3"[3]HYPERLINK\l"cite_note-4"[4]OneusefulapplicationofSWNTsisinthedevelopmentofthefirstintermolecularHYPERLINK"http://en.wikipedia.org/wiki/Field-effect_transistors"field-effecttransistors(FET).ThefirstintermolecularHYPERLINK"http://en.wikipedia.org/wiki/Logic_gate"logicgateusingSWCNTFETswasmadein2001.HYPERLINK\l"cite_note-5"[5]Alogicgaterequiresbothap-FETandann-FET.BecauseSWNTsarep-FETswhenexposedtooxygenandn-FETsotherwise,itispossibletoprotecthalfofanSWNTfromoxygenexposure,whileexposingtheotherhalftooxygen.ThisresultsinasingleSWNTthatactsasaNOTlogicgatewithbothpandn-typeFETswithinthesamemolecule.Single-wallednanotubesaredroppingprecipitouslyinprice,fromaround$1500pergramasof2000toretailpricesofaround$50pergramofas-produced40–60%byweightSWNTsasofMarch2010Multi-walledMulti-wallednanotubes(MWNT)consistofmultiplerolledlayers(concentrictubes)ofgraphene.Therearetwomodelsthatcanbeusedtodescribethestructuresofmulti-wallednanotubes.IntheHYPERLINK"http://en.wikipedia.org/wiki/Matryoshka_doll"RussianDollmodel,sheetsofgraphitearearrangedinconcentriccylinders,e.g.,a(0,8)single-wallednanotube(SWNT)withinalarger(0,17)single-wallednanotube.IntheHYPERLINK"http://en.wikipedia.org/wiki/Scroll_(parchment)"Parchmentmodel,asinglesheetofgraphiteisrolledinarounditself,resemblingascrollofparchmentorarollednewspaper.Theinterlayerdistanceinmulti-wallednanotubesisclosetothedistancebetweengraphenelayersingraphite,approximately3.4Å.TheRussianDollstructureisobservedmorecommonly.ItsindividualshellscanbedescribedasSWNTs,whichcanbemetallicorsemiconducting.Becauseofstatisticalprobabilityandrestrictionsontherelativediametersoftheindividualtubes,oneoftheshells,andthusthewholeMWNT,isusuallyazero-gapmetal.Double-walledcarbonnanotubes(DWNT)formaspecialclassofnanotubesbecausetheirmorphologyandpropertiesaresimilartothoseofSWNTbuttheirresistancetochemicalsissignificantlyimproved.ThisisespeciallyimportantwhenHYPERLINK"http://en.wikipedia.org/wiki/Surface_functionalization"functionalizationisrequired(thismeansgraftingofchemicalfunctionsatthesurfaceofthenanotubes)toaddnewpropertiestotheCNT.InthecaseofSWNT,covalentfunctionalizationwillbreaksomeC=CHYPERLINK"http://en.wikipedia.org/wiki/Double_bond"doublebonds,leaving"holes"inthestructureonthenanotubeand,thus,modifyingbothitsmechanicalandelectricalproperties.InthecaseofDWNT,onlytheouterwallismodified.DWNTsynthesisonthegram-scalewasfirstproposedin2003HYPERLINK\l"cite_note-6"[6]bytheCCVDtechnique,fromtheselectivereductionofoxidesolutionsinmethaneandhydrogen.ThetelescopicmotionabilityofinnershellsHYPERLINK\l"cite_note-7"[7]andtheiruniquemechanicalpropertiesHYPERLINK\l"cite_note-8"[8]permittousemulti-wallednanotubesasmainmovablearmsincomingnanomechanicaldevices.RetractionforcethatoccurstotelescopicmotioncausedbytheHYPERLINK"http://en.wikipedia.org/wiki/Lennard-Jones_interaction"Lennard-Jonesinteractionbetweenshellsanditsvalueisabout1.5nN.HYPERLINK\l"cite_note-9"[9]TorusIntheory,ananotorusisacarbonnanotubebentintoaHYPERLINK"http://en.wikipedia.org/wiki/Torus"torus(doughnutshape).Nanotoriarepredictedtohavemanyuniqueproperties,suchasmagneticmoments1000timeslargerthanpreviouslyexpectedforcertainspecificradii.HYPERLINK\l"cite_note-nanotori-10"[10]PropertiessuchasHYPERLINK"http://en.wikipedia.org/wiki/Magnetic_moment"magneticmoment,thermalstability,etc.varywidelydependingonradiusofthetorusandradiusofthetube.NanobudHYPERLINK"http://en.wikipedia.org/wiki/Carbon_nanobud"Carbonnanobudsareanewlycreatedmaterialcombiningtwopreviouslydiscoveredallotropesofcarbon:carbonnanotubesandHYPERLINK"http://en.wikipedia.org/wiki/Fullerene"fullerenes.Inthisnewmaterial,fullerene-like"buds"arecovalentlybondedtotheoutersidewallsoftheunderlyingcarbonnanotube.Thishybridmaterialhasusefulpropertiesofbothfullerenesandcarbonnanotubes.Inparticular,theyhavebeenfoundtobeexceptionallygoodfieldemitters.Incompositematerials,theattachedfullerenemoleculesmayfunctionasmolecularanchorspreventingslippingofthenanotubes,thusimprovingthecomposite’smechanicalproperties.GraphenatedcarbonnanotubesGraphenatedCNTsarearelativelynewhybridthatcombinesHYPERLINK"http://en.wikipedia.org/wiki/Graphite"graphiticfoliatesgrownalongthesidewallsofmultiwalledorbamboostyleCNTs.Yuetal.HYPERLINK\l"cite_note-12"[12]reportedon"chemicallybondedgrapheneleaves"growingalongthesidewallsofCNTs.Stoneretal.HYPERLINK\l"cite_note-13"[13]describedthesestructuresas"graphenatedCNTs"andreportedintheiruseforenhancedHYPERLINK"http://en.wikipedia.org/wiki/Supercapacitor"supercapacitorperformance.Hsuetal.furtherreportedonsimilarstructuresformedoncarbonfiberpaper,alsoforuseinHYPERLINK"http://en.wikipedia.org/wiki/Supercapacitor"supercapacitorapplications.HYPERLINK\l"cite_note-14"[14]Thefoliatedensitycanvaryasafunctionofdepositionconditions(e.g.temperatureandtime)withtheirstructurerangingfromfewlayersofHYPERLINK"http://en.wikipedia.org/wiki/Graphene"graphene(<10)tothicker,moreHYPERLINK"http://en.wikipedia.org/wiki/Graphite"graphite-like.HYPERLINK\l"cite_note-15"[15]ThefundamentaladvantageofanintegratedHYPERLINK"http://en.wikipedia.org/wiki/Graphene"graphene-CNTstructureisthehighsurfaceareathree-dimensionalframeworkoftheCNTscoupledwiththehighedgedensityofgraphene.HYPERLINK"http://en.wikipedia.org/wiki/Graphene"Grapheneedgesprovidesignificantlyhigherchargedensityandreactivitythanthebasalplane,buttheyaredifficulttoarrangeinathree-dimensional,highvolume-densitygeometry.CNTsarereadilyalignedinahighdensitygeometry(i.e.,averticallyalignedforest)HYPERLINK\l"cite_note-16"[16]butlackhighchargedensitysurfaces—thesidewallsoftheCNTsaresimilartothebasalplaneofgrapheneandexhibitlowchargedensityexceptwhereedgedefectsexist.DepositingahighdensityofgraphenefoliatesalongthelengthofalignedCNTscansignificantlyincreasethetotalHYPERLINK"http://en.wikipedia.org/wiki/Capacitance"chargecapacityperunitofnominalareaascomparedtoothercarbonnanostructures.HYPERLINK\l"cite_note-17"[NitrogenDopedCarbonNanotubesNitrogendopedcarbonnanotubes(N-CNT's),canbeproducedthrough5mainmethods,HYPERLINK"http://en.wikipedia.org/wiki/Chemical_Vapor_Deposition"ChemicalVaporDeposition,HYPERLINK\l"cite_note-18"[18]HYPERLINK\l"cite_note-19"[19]high-temperatureandhighpressurereactions,gas-solidreactionofamorphouscarbonwithNH3athightemeprature,HYPERLINK\l"cite_note-20"[20]solidreaction,HYPERLINK\l"cite_note-21"[21]andsolvothermalsynthesis.HYPERLINK\l"cite_note-22"[22]N-CNTscanalsobepreparedbyaCVDmethodofpyrolysizingHYPERLINK"http://en.wikipedia.org/wiki/Melamine"melamineunderAratelevatedtemperaturesof800oC-980oC.HoweversynthesisviaCVDandmelamineresultsintheformationofbamboostructuredCNTs.XPSspectraofgrownN-CNT'srevealsnitrogeninfivemaincomponents,pyridinicnitrogen,pyrrolicnitrogen,quaternanrynitrogen,andnitrogenoxides.Furthermoresynthesistemperatureaffectsthetypeofnitrogenconfiguration.HYPERLINK\l"cite_note-23"[23]HYPERLINK"http://en.wikipedia.org/wiki/Nitrogen"NitrogendopingplaysapivotalroleinHYPERLINK"http://en.wikipedia.org/wiki/Lithium"Lithiumstorage.N-dopingprovidesdefectsinthewallsofCNT'sallowingforLiionstodiffuseintointerwallspace.ItalsoincreasescapacitybyprovidingmorefavorablebindofN-dopedsites.N-CNT'sarealsomuchmorereactivetoHYPERLINK"http://en.wikipedia.org/wiki/Metal_oxide"metaloxidenanoparticledepositionwhichcanfurtherenhancestoragecapacity,especiallyinanodematerialsforHYPERLINK"http://en.wikipedia.org/wiki/Lithium-ion_battery"Li-ionbatteries.HYPERLINK\l"cite_note-24"PeapodAHYPERLINK"http://en.wikipedia.org/w/index.php?title=Carbon_peapod&action=edit&redlink=1"CarbonpeapodHYPERLINK\l"cite_note-25"isanovelhybridcarbonmaterialwhichtrapsfullereneinsideacarbonnanotube.Itcanpossessinterestingmagneticpropertieswithheatingandirradiating.Itcanalsobeappliedasanoscillatorduringtheoreticalinvestigationsandpredictions.HYPERLINK\l"cite_note-27"Cup-stackedcarbonnanotubesCup-stackedcarbonnanotubes(CSCNTs)differfromotherquasi-1Dcarbonstructures,whichnormallybehaveasquasi-metallicconductorsofelectrons.CSCNTsexhibitsemiconductingbehaviorsduetothestackingmicrostructureofgraphenelayers.HYPERLINK\l"cite_note-29"[ExtremecarbonnanotubesTheobservationofthelongestcarbonnanotubes(18.5cmlong)wasreportedin2009.ThesenanotubesweregrownonSisubstratesusinganimprovedHYPERLINK"http://en.wikipedia.org/wiki/Chemical_vapor_deposition"chemicalvapordeposition(CVD)methodandrepresentelectricallyuniformarraysofsingle-walledcarbonnanotubes.HYPERLINK\l"cite_note-Longest-1"[1]Theshortestcarbonnanotubeistheorganiccompoundcycloparaphenylene,whichwassynthesizedinearly2009.HYPERLINK\l"cite_note-30"[30]HYPERLINK\l"cite_note-31"[31]HYPERLINK\l"cite_note-32"[32]Thethinnestcarbonnanotubeisarmchair(2,2)CNTwithadiameterof3Å.Thisnanotubewasgrowninsideamulti-walledcarbonnanotube.AssigningofcarbonnanotubetypewasdonebycombinationofHYPERLINK"http://en.wikipedia.org/wiki/High-resolution_transmission_electron_microscopy"high-resolutiontransmissionelectronmicroscopy(HRTEM),HYPERLINK"http://en.wikipedia.org/wiki/Raman_spectroscopy"RamanspectroscopyandHYPERLINK"http://en.wikipedia.org/wiki/Density_functional_theory"densityfunctionaltheory(DFT)calculations.HYPERLINK\l"cite_note-Smallest_at_MWCNT-33"[33]Thethinnestfreestandingsingle-walledcarbonnanotubeisabout4.3Åindiameter.Researcherssuggestedthatitcanbeeither(5,1)or(4,2)SWCNT,butexacttypeofcarbonnanotuberemainsquestionable.HYPERLINK\l"cite_note-Smallest-34"[34](3,3),(4,3)and(5,1)carbonnanotubes(allabout4Åindiameter)wereunambiguouslyidentifiedusingmorepreciseaberration-correctedHYPERLINK"http://en.wikipedia.org/wiki/High-resolution_transmission_electron_microscopy"high-resolutiontransmissionelectronmicroscopy.However,theywerefoundinsideofdouble-walledcarbonnanotubes.HYPERLINK\l"cite_note-Smallest_at_DWCNT-35"[