Nanomaterials-lecture

NanoparticleSizeEffect-onFormationofFilamentandCNTTypeBCDMostpopulateddiameterinnm19.10.510.60.56.80.5RatioMWnTs/Filaments±10%00.00228.6SEM-SamplesBandCat900K,âc=20,O/H=0.1and1atmwith50%heliumAsthesizeofNinanoparticlesdecreasesthedensityofMWnTincreaseswhilethedensityoffilamentsdecreasesC,50%He,900K5µm500nmD,50%He,900KAbetterorderedstructure(lesskinks/unitlength).AuniformtubularstructureInertGasEffect-onStructureofFilaments20nm0%He20nm50%HeTEM-Moreorderedstructureoffilaments(right)synthesizedat900K,âc=20,O/H=0.1,1atmwithhelium(SampleB)InertGasEffect-onInternalStructureofCNT(SampleC)Additionofinertgasintoreactantsinstigatestransformofmultiwallstructurefromfilament.ThismaybebecausethediameteroftheNiparticle/nanotubedecreased.TEM-CNTinternalstructureevolutionat900K,âc=20,O/H=0.1and1atm,withhelium10nm50%He10nm50%He500nm50%He00.511.522.53101520GasphaseâcRateofweightgain(g/min)Figure7:Linearincreaseofrateofweightgainwithâcat900Kand1atmontypeC(10.6nm).CarbonActivityEffect-onCNT(SampleC)WeightgainwithâcLengthofcarbonnanotubesincreasewithâc.500nm500nm500nm1minofreaction5minofreaction10minofreactionSEM-CNTevolutionat900K,âc=20,O/H=0.1and1atm115145120Nucleationdensity(#/m210%)1051Reactiontime(minutes)TemperatureEffect-onFilaments/CNT(SampleC)MWnTswereformedat925Kand950K.Filamentswereformedat975Kand1000K.Attemperature950K,Niparticlessinteredduringreaction.SinteringofNiparticlesatT=950Kandhigher,decreasingMWnTsnucleation950K200nm975K200nm9009259509751000Temperature(K)021816141210468DensityofMWnT/cm2x10-90.E+002.E+074.E+076.E+078.E+071.E+081.E+081.E+082.E+082.E+089009259509751000Temperature(K)1010.51111.51212.513MostpopulateddiameterofNiparticles021816141210468DensityofMWnT/cm2x10-9O/HEffect-onFilamentsandCNT(SampleB)1µmO/H=0.1O/H=0.21µmSEM-SamplesBafterexposureat900K,âc=20and1atmwithincreasingO/HratioNucleationdensityofMWnTsincreasewithO/Hratioat900K,âc=20and1atm.NoMWnTswereformedwhenonlyCOandCO2wereused(O/H=)at900K.O/H=0.51µmSummaryInanH2,CO,CH4,CO2andH2Osystem,900Kand1atm:Multiwallcarbonnanotubesweresynthesizedwith–AreactantmixturewithO/H0.2,–Nickelnano-particlessmallerthan12nm.ProductiveformationofcarbonfilamentsonNiparticlesgreaterthan20nmindiameter.ThegrowthofcarbonfilamentsandMWnTstronglyrelatedtothepartialpressuresofCO,H2andCH4,temperatureandcarbonactivity.FabricationofCNTDevicesGrowthofpatterned,alignedMWNTarraysforfieldemission,flatpaneldisplay,andmicromanufacturingPatternedStructures100nm100nmDevelopmentinFuture→MiniaturizationandNovelDevicesRoadmapofNanoResearchDevelopmentApplicationsCommercializationR/DandApplicationStrategyMechanicalEngineeringBiologicalBiomedicinePhysicsChemistryStress,strain,displacement,elasticity,ductility…Mass,electronic,thermal,waves,vibration,magnetic,optic,nuclear,bonding,functionalgroups…DNA,RNA,NucleicAcid,Amino,Enzymes,spores…EnvironmentEngineeringEnergyEngineeringFuelcell,solarcell,battery,catalysis…NanoWorldChemicalEngineeringInorganic,organic,polymeric,catalytic,analytic…Hot,wet,dry,cold,soil,marine,air,pressure,stress,space…MetallurgyMaterialsFerrous,Non-ferrous,ceramics,composites,treating,processing…