电子显微分析

电子显微分析授课教师：章晓中教授办公室：东主楼(11区）一楼电镜实验室Tel：62773999e-mail:[e-mail]清华大学精品课教学手段•双语教学：–讲课：英文–作业、实验、考试用中文•使用多媒体和板书•教学内容课后会放在清华大学“网络学堂”上•无英文教材，有英文ppt课件和自编中文教材•推荐参考书Whylearnthiscourse?Question?Ifwehaveamaterialswithheterogeneouscompositionandwewanttoknowitsstructure,phaseandcomposition,whatmicrostructuralanalysistechniqueshallweuse?ABMethodsofmicrostructureanalysisThemostcommonlyusedmicrostructureanalysismethodsinmaterialsscienceandengineering•opticalmicroscopy•X-raydiffraction•electronmicroscopymicrostructuralanalysis•OpticalMicroscopyAdvantage:–observesurfacemorphology–Easytooperate–ResultinterpretationisstraightforwardDisadvantage:–Lowresolution(0.2m)–Cannotdocompositionanalysisandphaseanalysismicrostructuralanalysis•X-raydiffractionAdvantage:–phaseanalysis–Highaccuracy–GiveaveragecompositionDisadvantage:–Cannot“see”image–Cannotdo“localized”analysismicrostructuralanalysis•ElectronmicroscopyAdvantage:–Highresolution:TEM(1Å)，SEM(4Å）–Doimageobservation(BF,DF,HREM),structureanalysis(SAD,CBED),compositionanalysis(EDS)andelectronicstructureanalysis(EELS)ononeinstrument(TEM)–Candoanalysisinverysmallvolume(~nm3)microstructuralanalysis•ElectronmicroscopyDisadvantage:–onlygivelocalizedinformation–veryexpensive(US$:0.1-1million)–interpretationisnotstraightforward–operationiscomplex–SpecimenpreparationisdifficultWhylearnelectronmicroscopy•Thepropertiesofmaterialsaremainlydeterminedbyitsmicrostructure.Bycontrollingthemicrostructureofthematerials,onecanmakeamaterialwiththerequiredproperties.•Toachievesuchgoal,oneshouldfirst“know”themicrostructureofthematerials.•Electronmicroscopyisamethodtoanalysesthemicrostructureofthematerials，especiallyfornanomaterialsandnanotechnologyTopicsofthislecture•Comparisonofelectronmicroscopywithothermicrostructureanalysistechniques•Brieflyintroducevariouselectronmicroscopesandtheirapplication•Historyofdevelopmentofelectronmicroscopeandelectronmicroscopy•coursecontents,teachingtarget,teachingarrangementandreferencebooksDifferenttypeofelectronmicroscopes•TransmissionElectronMicroscope(TEM)•ScanningElectronMicroscope(SEM)•ElectronProbeMicroanalyzer(EPMA)•ScanningTransmissionElectronMicroscope(STEM)TransmissionElectronMicroscope(TEM)•Electronbeamgothroughthethinspecimen.Duetotheinteractionbetweentheincidentelectronbeamwiththespecimen,thetransmittedbeamwillgiveoutthestructuralandcompositionalinformationofmaterials.•Cando–Structuredetermination(BF,DF,HREM)–Phaseanalysis(SAD,NED,CBED)–Compositionanalysis(EDS,EELS)–Electronstructureanalysis(EELS)•resolution：1Å•specimen：thinspecimen(10-100nm)ThinspecimenScreen/detectorIncidentbeamJEM-2010FFEGTEMvariousTEMsFEITitanCharacterizationofnanomaterialsSumioIijima(饭岛澄男）discoveredcarbonnanotubesusingTEMin1991Nature，354(1991)56.TEMimagesStructuremodelofcarbonnanotubesHighresolutionTEM(HREM)ElectronDiffractionPatternSinglecrystalpolycrystalamorphousPhaseanalysisX-rayenergydispersivespectrometer（EDS）•compositionanalysis(fromelementofZ=4toZ=92)•elementdistributionConvergentBeamElectronDiffraction（CBED）•symmetryofcrystalstructure•thicknessofthespecimen•strainElectronEnergyLossSpectrometry(EELS)•AnalysisofchemicalcompositionfromH(Z=1)toU(Z=92).Energy(eV)05000100001500020000250003000035000EvaporatedCarbon2802852902953003053103153200200040006000800010000280285290295300305310315320DLCEnergy(eV)01000020000300004000050000600007000080000280285290295300305310315320Energy(eV)determinationofnatureofchemicalbondingDiamondGraphiteVirusstructureInfluenzavirusSARSvirusScanningElectronMicroscope(SEM)•Interactionofincidentelectronbeamwithmaterialsatsurfaceofspecimenresultsinmanyusefulsignals.•Usingthesesignalsonecandosurfacemorphologyobservationandcompositionanalysis•resolution：4Å•specimen：thickspecimenIncidentbeamdetectorThickspecimenJSM-6301FFEGSEMVariousSEMsQuanta400FEGESEMHitachiS5500SEMimage(IC)Cross-sectionofICshowinglayersBondingwireApplicationinMaterialsScienceApplicationinBio-science30umpseudo-KikuchipatternsGrainorientationdistributionElectronBackscatteredDiffraction(EBSD)ElectronbeamlithographysysteminSEMScanningProbeMicroscope（SPM)•ScanningTunnelingMicroscope(STM)•AtomicForceMicroscope(AFM)STMSPMScanningTunnelingMicroscope(STM)•resolution–Horizontal(x-ydirection):0.1nm–Vertical(zdirection):0.01nm•detectiondepth:1-2atomiclayer(nodamageonthespecimen)•Canworkinair,solution,vacuum•canonlybeusedforconductorandsemiconductorAtomicResolutiononSi(111)AtomicForceMicroscope(AFM)•resolution–Horizontal(x-ydirection):0.15nm–Vertical(zdirection):0.05nm•Canworkinair,solution,vacuum•canbeusedforbothconductorandinsulatorAtomicresolutiononcarbonnanotubes•measureforcebetweensurfaceatoms(smallestforce10-14-10-15N,smallestdisplacement10-2-10-4Å),•measuresurfaceelasticity,surfaceplasticity,frictionforce,adhesiveforce.•measuremagneticproperty•donano-manipulationAFMMagneticdomainwallsonaBaFe12O19singlecrystalIrononcopper(111)Lengthscaleofresearchobjectsofelectronmicroscopyandscanningprobemicroscopyopticalmicroscopy10-12m10-10m10-8m10-6mnanometerElectronmicroscopyNearfieldopticalmicr