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1、1ELECTRONICANDMECHANICALPROPERTIESOFCARBONNANOTUBES111111L.Forr—,J.-P.Salvetat,J.-M.Bonard,R.Bacsa,N.H.Thomson,S.Garaj,111223L.Thien-Nga,R.Ga‡l,A.Kulik,B.Ruzicka,L.Degiorgi,A.Bachtold,345C.Schšnenberger,S.Pekker,K.Hernadi1DŽpartementdePhysique,EPF-Lausanne,CH-1015Laus
2、anne,Switzerland2LaboratoriumfŸrFestkšrperphysik,ETH-ZŸrich,CH-8093ZŸrich,Switzerland3InstitutfŸrPhysik,UniversitŠtBasel,Klingelbergstr.82,CH-4056Basel,Switzerland4ResearchInstituteforSolidStatePhysicsandOptics,H-1525Budapest,Hungary5AppliedandEnvironmentalChemistryDe
3、partment,JATE,H-6720Szeged,HungaryINTRODUCTIONInterestincarbonnanotubeshasgrownataveryrapidratebecauseoftheirmanyexceptionalproperties,whichspanthespectrumfrommechanicalandchemicalrobustnesstonovelelectronictransportproperties.Theirphysics,chemistryandperspectivesfora
4、pplicationsareverychallenging.BelowwehighlightthemainresultsoftheLausannegroupandtheircollaboratorsontransport,electronspinresonance,elasticandfieldemissionpropertiesofsinglewall(SWNT)andmulti-wall(MWNT)carbonnanotubes.SAMPLESWeuseMWNTsproducedbyarcdischargeorbytherma
5、ldecompositionofhydrocarbons,andSWNTseitherpreparedbythearcdischargemethodinthepresenceofcatalystsorcommerciallyavailable(Carbolex,RiceUniversity,MER,DEL).ThefirststepinthestudyofCNTsistechnological:theirpurification.ThisisespeciallytrueforSWNTs,whichareseverelycontam
6、inatedwithmagneticcatalystparticles.Thepurityofthearc-dischargefabricatedMWNTsismuchbetter,sincemagneticmaterialsarenotusedintheir2production.Neverthelesstheyhavetobeseparatedfromgraphiticflakes,polyhedralparticlesandamorphouscarbonpresentintherawsoot.ForMWNTs,wehaved
7、evelopedasoft1purificationmethod,whichusesthepropertiesofcolloidalsuspensions.Westartedthepurificationwithasuspensionpreparedfrom500mlofdistilledwater,2.5gofSDS(sodiumdodecylsulfate;acommonsurfactant)and50mgofMWNTarcpowdersonicatedfor15minutes.Sedimentationandcentrifu
8、gation(at5000rpmfor10minutes)removedallgraphiticparticleslargerthan500nmfromthesolution,asconfirmedbylowmagnificationSEMobse