Introduction-to-Nanomaterials纳米介绍

[e-mail]dIntroduction2DefinitionandCharacteristics2Preparationmethodsofnanoparticles4Nanofilmandnanofilter4Nanostructuredmaterial4Nanocomposite4Carbonnanotube(supplement)2Keptinreserve2OutlineObjectiveStudyofthedefinition﹑Characteristics﹑SystemsandPreparationmethodsofthenanomaterials.Masterthekeywordsofthenanomaterialandnanotechnology.TeachingmethodTwolanguagesareusedinthiscourse:ChineseandEnglish.AllthePPTwillbeshowninEnglish.AssessmentWrittenorOralexaminationIt’suptoyou!!OutlineSometipsPreparethecoursecarefully.PayattentiontotheKeywords.5minutesinparticipationAtthebeginningofeachlesson,youwillhaveachancetogiveusatalkwithEnglishin5minutes.Thetopicisfree,aboutthecourse,study,socialissues,livingandsoon.Thevolunteercanhavethebonusinthefinalmark.IntroductionNanotechnologyandnanomaterialXeatomsonNisurfaceIntroductionFeatomsonCusurfaceDefinitionofNanomaterialsKeywords:Nano,Macro,Micro.Nano:anewmetrology,1n=10-9.Macro:hasminimumlimit(threshold),notoplimit,suchasthenormalvisiblematter.Micro:hasupperlimit,nominimumlimit,suchasatom,molecule,nucleusIntroductionIntroductionHasthebuildingblockswhichhasatleastonedimensioninthenanometerscale(1-100nm);HasthedifferentcharacteristiccomparingwiththebulkmaterialsNanomaterialsIntroductionBasedonthespatialdimension,thenanomaterialscanbeclassifiedas:Zerodimension:threedimensionsareallinnanometerscale-----quantumdot;Onedimension:twodimensionsareinnanometerscale-----quantumline;Twodimension:onlyonedimensionisinnanometerscale-----quantumwell.IntroductionClassifythenanomaterialsbasedonthenarrowsensedefinitionofthenanomaterials:1.Atomiccluster:smallparticlescomposedbymanyatoms,size:1nm,thefifthstate.Uniqueproperties:a.surfaceorinterfacialeffect;b.Magicnumbereffect;c.Coulombexplosion;d.Oscillationoftheworkfunction.IntroductionNanoparticles:Theparticlewhichonlycanbeseenbytheelectronicmicroscope.Size:normalvisibleparticlesnanoparticlesatomicclusterUniqueproperties:quantumeffect,surfaceeffect,fractalaggregation.IntroductionCarbonnano-sphereRepresentative:C60,60carbonatoms,32faces,20hexagons,12pentagons,likethefootball.IntroductionTheheatedCarbonnanotubeinthemicroscope.IntroductionCarbonnanotube(CNT)Diameter:1-20nmLength:nm-umIntroductionNanofilmandnanofilterTwokinds:1.Containingthenanoparticlesoratomclusters:MatrixFilm;2.Thethicknessofthefilmisinthenanameterscale,thevalueofthethicknessisneartothefreepathofelectronsandDebyelength.IntroductionNanostructuredmaterials:Thesolidhasnanostructurescanbecallednanostructuredmaterial.ThesynthesisoftheNanostructures:top-downandbottom-up.IntroductionNanocomposite:Reinforcingphasemustbeinthenanometerscale,thematrixhasnorestriction.0-0,0-3,0-2.KeywordsinnextlectureQuantumsizeeffect;Smallsizeeffect;Surfaceeffect;Tunnelingeffect;Superparamagnetism;CoerciveforceBlueshift.Chapter11.BasicpropertiesofnanoparticlesQuantumsizeeffect,smallsizeeffect,Surfaceeffect,tunnelingeffect.2.Physicalpropertiesofnanoparticlesmagneticproperties,opticalproperties.Chapter11.2.2QuantumsizeeffectAsthematerialisminiaturizedinnano-scale,theenergyspectrumbecomesdiscrete.Asaresult,thebandgapbecomessizedependent.Thereisasmallandfiniteseparationbetweenenergylevels.Chapter1ConductorSemiconductorInsulatorChapter11.2.3SmallsizeeffectThesizeofthesuperfineparticlesisclosetosomecharacteristiclength,thepropertieswillbechangedsignificantly.Chapter1Opticalproperties:allthesuperfinemetalparticlesshowBLACK.Thermodynamicproperties:themeltingpointofthesuperfineparticlesdecreases.Magneticproperties:superparamagnetismMechanicalproperties:Ceramiccanshowgoodtenacity.Chapter11.2.4SurfaceeffectLargespecificsurfacearealeadtothehighsurfaceenergy.Chapter11.2.5TunnelingeffectTunnelingreferstophenomenaofaparticle'sabilitytopenetrateenergybarrierswithinelectronicstructures.Chapter11.3Physicalproperties1.3.1structureandmodalityCd4Se:cadmiumselenideD=50nmChapter11.3.2ThermodynamicpropertiesPlentyofatomsattheinterfaceorsurfacehavehigherenergywhichcanmakethemeltingpointofthesolidreduce.Chapter11.3.3MagneticpropertiesFerromagnetism,Paramagnetism,Diamagnetism,SuperparamagnetismChapter1HysteresisloopofferromagneticmaterialM:magnetization(intensity)H:magneticfieldintensityB:magneticinduction(intensity)Mr:RemanenceHCM:CoerciveforceChapter1HystersisloopofthemagnetitenanoparticleswithsuperparamagnetismChapter1CurietemperatureTcthetransformationtemperature(criticaltemperature)offerromagnetandparamagneticsubstanceChapter11.3.4OpticalpropertiesBlueshift:hypsochromicshift.Thepeakoftheabsorptionshiftstotheshortwavelength.Redshift:thepeakoftheabsorptionshiftstothelongwavelength.Chapter1QuantumconfinementeffectThequantumconfinementeffectcanbeobservedoncethediameteroftheparticleisofthesamemagnitudeasthewavelengthoftheelectronwavefunction.Exciton:aboundstateofanelectronandahole.Electricallyneutral.Chapter1IlluminationofnanoparticlesTheincidentlightwithcertainwavelengthcanmakethenanoparticleswhichhaveth