1、InternationalStandardISO25498Thirdedition2025-05MicrobeamanalysisAnalyticalelectronmicroscopySelectedareaelectrondiffractionanalysisusingatransmissionelectronmicroscopeAnalyseparmicrofaisceauxMicroscopieelectroniqueanalytiqueAnalysepardiffractionparselectiond,aireaumoyend,unmicroscopeelectroniqueent
2、ransmissionReferencenumberISO25498:2025(en)COPYRIGHTPROTECTEDDOCUMENTISO2025Allrightsreserved.Unlessotherwisespecified,orrequiredinthecontextofitsimplementation,nopartofthispublicationmaybereproducedorutilizedotherwiseinanyformorbyanymeans,electronicormechanical,includingphotocopying,orpostingonthei
3、nternetoranintranet,withoutpriorwrittenpermission.PermissioncanberequestedfromeitherISOattheaddressbeloworISO,smemberbodyinthecountryoftherequester.ISOcopyrightofficeCP401Ch.deBlandonnet8CH-1214Vernier,GenevaPhone:+4122749Ol11Email:copyrightiso.orgWebsite:www.iso.orgPublishedinSwitzerlandContentsPag
4、eForewordivIntroductionv1 Scope12 Normativereferences13 Terms,definitionsandabbreviations13.1 Termsanddefinitions13.2 Abbreviatedtermsandsymbols34 Principle34.1 General34.2 Spotdiffractionpattern44.3 Kikuchipattern64.4 Diffractionpatternofpolycrystallinespecimen75 Referencematerials86 Apparatus86.1
5、Transmissionelectronmicroscope(TEM)86.2 RecordingofSAEDpatternsandimages87 Preparationofspecimens98 Procedure98.1 Instrumentpreparation98.2 ProcedureforacquiringSAEDpatternsfromasinglecrystal108.3 Determinationofdiffractionconstant,L129 MeasurementandsolutionoftheSAEDpatterns149.1 Selectionofthebasi
6、cparallelogram149.2 Indexingdiffractionspots1510 180oambiguity1611 Uncertaintyestimation1611.1 General1611.2 Uncertaintyincameraconstant1711.3 Calibrationwithareferencematerial1711.4 Uncertaintyind-spacingvalues18Annex A (informative)Interplanarspacingsofreferences20Annex B (informative)Spotdiffract
7、ionpatternsofsinglecrystalsforBCC1FCCandHCPstructure21Bibliography42ForewordISO(theInternationalOrganizationforStandardization)isaworldwidefederationofnationalstandardsbodies(ISOmemberbodies).TheworkofpreparingInternationalStandardsisnormallycarriedoutthroughISOtechnicalcommittees.Eachmemberbodyinte
8、restedinasubjectforwhichatechnicalcommitteehasbeenestablishedhastherighttoberepresentedonthatcommittee.Internationalorganizations,governmentalandnon-governmental,inliaisonwithISO,alsotakepartinthework.ISOcollaboratescloselywiththeInternationalElectrotechnicalCommission(IEC)onallmattersofelectrotechn
9、icalstandardization.TheproceduresusedtodevelopthisdocumentandthoseintendedforitsfurthermaintenancearedescribedintheISO/IECDirectives,Part1.Inparticular,thedifferentapprovalcriterianeededforthedifferenttypesofISOdocumentshouldbenoted.ThisdocumentwasdraftedinaccordancewiththeeditorialrulesoftheISO/IEC
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11、vednoticeof（八）patent(三)whichmayberequiredtoimplementthisdocument.However,implementersarecautionedthatthismaynotrepresentthelatestinformation,whichmaybeobtainedfromthepatentdatabaseavailableatwww.iso.org/patents.ISOshallnotbeheldresponsibleforidentifyinganyorallsuchpatentrights.Anytradenameusedinthis
12、documentisinformationgivenfortheconvenienceofusersanddoesnotconstituteanendorsement.Foranexplanationofthevoluntarynatureofstandards,themeaningofISOspecifictermsandexpressionsrelatedtoconformityassessment,aswellasinformationaboutISOsadherencetotheWorldTradeOrganization(WTO)principlesintheTechnicalBar
13、rierstoTrade(TBT),SeeWWW.isoQrgisoforeword.htmLThisdocumentwaspreparedbyTechnicalCommitteeISO/TC202,Microbeamanalysis,SubcommitteeSC3,Analyticalelectronmicroscopy.Thisthirdeditioncancelsandreplacesthesecondedition(ISO25498:2018),whichhasbeentechnicallyrevised.Themainchangesareasfollows:一Scopehasbeen
14、revised;一ISO/IEC17025hasbeenmovedfromnormativereferencestobibliography;一FigUre1hasbeenreplaced;一Subclause6.3hasbeendeleted;一Subclause8.3.6hasbeendeleted,thecontentof8.3.6hasbeenmovedto8.3.2;一SUbClaUSe925hasbeenaddedandthefollowingsubclausehasbeenrenumbered;一CIaUSeIlhasbeenrevised,11.1,11.2,11.3andIl
15、4havebeenadded;一SUbClaUSeSB41andB42havebeenadded;一BibliographyhasbeenupdatedandISO/IECGuide98-3(GUM:1995)hasbeenadded.Anyfeedbackorquestionsonthisdocumentshouldbedirectedtotheusersnationalstandardsbody.Acompletelistingofthesebodiescanbefoundatwww.iso.org/membnrs.htmLIntroductionElectrondiffractiont
16、echniquesarewidelyusedintransmissionelectronmicroscopy(TEM)studies.Applicationsincludephaseidentification,determinationofthecrystallographiclatticetypeandlatticeparameters,crystalorientationandtheorientationrelationshipbetweentwophases,phasetransformations,habitplanesanddefects,twinsandinterfaces,as
17、wellasstudiesofpreferredcrystalorientations(texture).Whileseveralcomplementarytechniqueshavebeendeveloped,forexamplemicrodiffraction,nanodiffraction,convergentbeamdiffractionandreflecteddiffraction,theselectedareaelectrondiffraction(SAED)techniqueisthemostfrequentlyemployed.Thistechniqueallowsdirect
18、analysisofsmallareasonthinspecimensfromavarietyofcrystallinesubstances.ItisroutinelyperformedonmostTEMsintheworld.TheSAEDisalsoasupplementarytechniqueforacquisitionofhigh-resolutionimages,microdiffractionorconvergentbeamdiffractionstudies.Theinformationgeneratediswidelyappliedinstudiesforthedevelopm
19、entofnewmaterials,improvingstructureand/orpropertiesofvariousmaterialsaswellasforinspectionandqualitycontrolpurpose.ThebasicprincipleoftheSAEDmethodisdescribedinthisdocument.TheexperimentalprocedurefortheacquirementofSAEDpatterns,indexingofthediffractionpatternsanddeterminationofthediffractionconsta
20、ntarespecified.ISO25498isintendedforuseorreferenceastechnicalregulationfortransmissionelectronmicroscopy.MicrobeamanalysisAnalyticalelectronmicroscopySelectedareaelectrondiffractionanalysisusingatransmissionelectronmicroscope1 ScopeThisdocumentspecifiesthemethodforselectedareaelectrondiffraction(SAE
21、D)analysisusingatransmissionelectronmicroscope(TEM)toanalysethincrystallinespecimens.Thisdocumentappliestotestareasofmicrometresandsub-micrometresinsize.Theminimumdiameteroftheselectedareainaspecimenwhichcanbeanalysedbythismethodisrestrictedbythesphericalaberrationcoefficientoftheobjectivelensofthem
22、icroscopeandapproacheshundredsofnanometresforamodernTEM.Whenthesizeofananalysedspecimenareaissmallerthanthesphericalaberrationcoefficientrestriction,thisdocumentcanalsobeusedfortheanalysisprocedure.However,becauseoftheeffectofsphericalaberrationanddeviationofthespecimenheightposition,someofthediffra
23、ctioninformationinthepatterncanbegeneratedfromoutsideoftheareadefinedbytheselectedareaaperture.Insuchcases,theuseofmicrodiffraction(nano-beamdiffraction)orconvergentbeamdiffraction,whereavailable,canbepreferred.ThisdocumentisapplicabletotheacquisitionofSAEDpatternsfromcrystallinespecimens,indexingth
24、epatternsandcalibrationofthecameraconstant.2 NormativereferencesTherearenonormativereferencesinthisdocument.3 Terms,definitionsandabbreviationsForthepurposesofthisdocument,thefollowingtermsanddefinitionsapply.ISOandIECmaintainterminologydatabasesforuseinstandardizationatthefollowingaddresses:一ISOOnl
25、inebrowsingplatform:availableathttps:WWW.iso.org/obp一IECElectropedia:availableathttps:/WWW.electropedia.org/3.1 Termsanddefinitions3.1.1Millernotationindexingsystemforcrystallographicplanesanddirectionsincrystals,inwhichasetoflatticeplanesordirectionsisdescribedbythreeaxescoordinate3.1.2Miller-Brava
26、isnotationindexingsystemforcrystallographicplanesanddirectionsinhexagonalcrystals,inwhichasetoflatticeplanesordirectionsisdescribedbyfouraxescoordinate3.1.3interplanarspacingdhklperpendiculardistancebetweenconsecutiveplanesofthecrystallographicplaneset(hkl)3.1.4reciprocalvector9hklvectorintherecipro
27、callatticeNote1toentry:Thereciprocalvector,。力士/,isnormaltothecrystallographicplane(hkl)withitsmagnitudeinverselyproportionaltointerplanarspacingdhki(3.1.3).3.1.5RvectorRhklcoordinatevectorfromthedirectbeam,OO0,toadiffractionspot,hkl,inazonediffractionpatternNote1toentry:SeeFigUreL3.1.6cameralengthLe
28、ffectivedistancefromthespecimentothescreenorrecordingdeviceinatransmissionelectronmicroscopeindiffractionmode3.1.7cameraconstantdiffractionconstantLproductofthewavelengthoftheincidentelectronwaveandcameralength(3.1.6)SOURCE:ISO15932:2013,3.7.13.1.8brightfieldimageimageformedusingonlythenon-scattered
29、beam,selectedbyobservationofthebackfocalplaneoftheobjectivelensandusingtheobjectiveaperturetocutoutalldiffractedbeamsSOURCE:ISO15932:2013,5.53.1.9darkfieldimageimageformedbyadiffractedbeamonlybyusingtheobjectiveapertureforselectionorbycollectingthediffractedbeamswithanannulardark-fielddetectorSOURCE
30、ISO15932:2013,5.63.1.10energy-dispersiveX-rayspectrometryEDSanalyticaltechniquewhichenablestheelementalanalysisorchemicalcharacterizationofaspecimenbyanalysingcharacteristicX-rayemittedbythematterinresponsetoelectronirradiationSOURCE:ISO15932:2013,6.63.1.11eucentricpositionspecimenpositionatwhichth
31、eimageexhibitsminimallateralmotionresultingfromspecimentilting3.1.12selectedarea(selector)aperturemoveablediaphragmthatisusedtoselectonlyradiationscatteredfromaspecificareaofthespecimentocontributetotheformationofadiffractionpatternSOURCE:ISO15932:2013,3.2.3.53.1.13BraggangleBanglebetweentheincident
32、beamandtheatomicplanes,atwhichdiffractiontakesplace3.2 AbbreviatedtermsandsymbolsBCCbody-centredcubicstructureFCCface-centredcubicstructureHCPhexagonalclose-packedstructureSAEDselectedareaelectrondiffractionTEMtransmissionelectronmicroscope(hkl)MillerindicesofaspecificsetofcrystallographicplaneshklM
33、illerindiceswhichdenoteafamilyofcrystallographicplanesuvwMillerindicesofaspecificcrystallographicdirectionorazoneaxis(vv)*NotationforasetofplanesinthereciprocallatticeNOTEThenormalofthereciprocalplaneuvw)*isparalleltothecrystallographiczoneaxisuvw4 Principle4.1 GeneralWhenanenergeticelectronbeamisin
34、cidentuponathincrystalspecimeninatransmissionelectronmicroscope,adiffractionpatternwillbeproducedinthebackfocalplaneoftheobjectivelens.Thispatternismagnifiedbytheintermediateandprojectorlenses,thendisplayedonaviewingscreenandrecorded(seeReference3j4,5).ThispatterncanalsobedisplayedonamonitoriftheTEM
35、isequippedwithadigitalcamerasystem.Thegeometricrelationshipoftheparametersforselectedareaelectrondiffraction(SAED)techniquecanbeunderstoodthroughtheEwaldsphereconstruction,whichisillustratedinFigure1.Key1 incidentbeam2 specimen3 directbeam4 diffractedbeam5 Ewaldsphere6 reciprocalvectorghkl7 diffract
36、ionpattern8 RhklVeCtOrListhediffractioncameralength;如isBraggangle;入isthewavelengthoftheincidentelectronbeam.Figure1EwaldsphereconstructionillustratingthediffractiongeometryinTEM4.2SpotdiffractionpatternThediffractionpatternofasinglecrystalappearsasanarrayof“spots”,thebasicunitofwhichischaracterizedb
37、yaparallelogram.AnexampleofthespotdiffractionpatternisshowninFigure2.Eachspotcorrespondstodiffractionfromaspecificsetofcrystallatticeplanesinthespecimen,denotedbyMillerindices(hkl).Thevector,Rhk,isdefinedbythepositionofthediffractedspot,hklfrelativetopositiononthepatterncorrespondingtothedirectbeam,
38、i.e.thecentre-spot,OOO,ofthepattern.Itisparalleltothenormalofthereflectingplane,(hW).ThemagnitudeofRhklisinverselyproportionaltotheInterplanarspacing,djthediffractingplane,(hkl)(seeReferences4to9.Inthecontextofthisdocument,vectorsRhk1l1Rhk2(Rijg)and(P2c11+2c22)1areSimglifiedasRlfR2fR2nlandR1+2respec
39、tively.Theincludedanglebetweenvectors,R1andR2,isdenotedby*.ThebasicparallelogramisdefinedbyRlandR2wheretheyaretheshortestandnextshortestinthepatternrespectivelyandnotalongacommonline.Thespot,h2k212,ispositionedanticlockwisearoundthecentrespotrelativetospot,hkl1.Becausethecentre-spotisoftenverybright
40、itisoftendifficulttodeterminetheexactcentreofthepattern.Therefore,apracticalprocedureistoestablishthemagnitudeofRhkbymeasuringthedistancebetweenthespots,hklandhklonthediffractionpatternanddividingbytwo,i.e.Rhkl=局).OntheexamplepatternshowninFigUre2,themagnitudeofR1,R2and2isobtainedfrom$R1+RD，22+2Jan
41、d2(正+20respectively.KeyR1isthevectorfrom000tospot,h1k1l1,theshortestvectorinthediffractionpatternR2isthevectorfrom000tospot,h2k2l2,thenextshortestvectorNOTEThebasicparallelogramisconstitutedbyR1and4Figure2ExampleofthespotdiffractionpatternfromasinglecrystalTherelationshipbetweentheInterplanarspacing
42、dhkt,andthemagnitudeofRhklforareflectingplane,(hkl),canbeapproximatelyexpressedasshowninFOrmUIa(1)(seeReferences7and8J:L=RhklXdhkl山MRhkIL)2=RhkiXdhkl(1口A)(1)whereisequaltoListhediffractioncameralengthandequaltof0MiMp;wheref0isthefocallength,inmillimetres,oftheobjectivelensinthemicroscope;Miisthemag
43、nificationoftheintermediatelens;MPisthemagnificationoftheprojectorlenses;Listhecameraconstant(ordiffractionconstant)ofthetransmissionelectronmicroscopeoperatingundertheparticularsetofconditions.Thisparametercanbedeterminedfromthediffractionpatternofacrystallinespecimenofknownlatticeparameters(see8.3
44、);isthewavelength,innanometres,oftheincidentelectronbeamwhichisdependentupontheacceleratingvoltageandcanbegivenbyFOnrIUIa(2)(seeReference4J:Mnm)=(2)y(l+0,978810116y)whereVistheacceleratingvoltage,involts,oftheTEM;thefactorinparenthesisistherelativisticcorrection.FormostworkusingaTEM,thevalueofinForm
45、UIa(I)isusuallysmallerthan0,1%and,hence,amoresimplifiedFOmUIa(3)maybeused:Rhkldhkl=i(3)Forthederivationoftheaboveequation,refertothetextbooks(seeReferences4to9.TheuseofFOITnUIa(3)requiresmeasuringthelengthofRhk：Since,asmentionedearlier,thelocationofthepatterncentremaynotbeeasilydetermined;itisrecomm
46、endedthatthedistancemeasurementtaken,2Rhkjbefromthehc1diffractedspottothehsgotonthepattern.Thisisequivalenttoadiametermeasurementontheringpatternfromapolycrystallinespecimen(Section4.4andFigure4).ToobtaintheInterplanarinformation,themeasureddistance,2R或支,ishalvedandFOrmUIa(3)applied.Ifthecameraconst
47、antisknown,theInterplanarspacing,dhki,ofplane,(hkl),canbecalculated.Theincludedanglebetweenanytwovectors,RhIklhandR,canalsobemeasuredonthediffractionpattern.Thisisequaltotheanglebetweenthecorrespondingcrystallographicplanes,(hkl1)and(hk2)Sincediffractiondatafromasinglepatternwillprovideinformationonalimitednumberofthepossiblediffractingplanesinaspecimenarea,itisnecessarytoacquireadditionaldiffractionpatternsfromthesamearea(orfromdifferentgrains/particlesofthesamephase).Thisrequireseitherthetiltingofthespecimenortheavailabilityofdifferentlyorientedgrainsorparticlesofthesam
