defect engineering a path toward exceeding perfection 2017 hamed attariani学术.pdf

该【defect engineering a path toward exceeding perfection 2017 hamed attariani学术 】是由【湘云】上传分享，文档一共【7】页，该文档可以免费在线阅读，需要了解更多关于【defect engineering a path toward exceeding perfection 2017 hamed attariani学术 】的内容，可以使用淘豆网的站内搜索功能，选择自己适合的文档，以下文字是截取该文章内的部分文字，如需要获得完整电子版，请下载此文档到您的设备，方便您编辑和打印。essarticlepublishedunderanACSAuthorChoiceLicense,://pubs./journal/acsodfDefectEngineering:APathtowardExceedingPerfectionHamedAttariani,*,?,?KasraMomeni,§andKyleAdkins??DepartmentofMechanicalandMaterialsEngineering,WrightStateUniversity,Dayton,Ohio45435,UnitedStates?EngineeringProgram,WrightStateUniversity-LakeCampus,Celina,Ohio45822,UnitedStates§DepartmentofMechanicalEngineering,LouisianaTechUniversity,Ruston,Louisiana71272,UnitedStates*SSupportingInformationABSTRACT:,suchasstackingfaults(SFs),arestillformingduringthesynthesisofnanomaterialsand,monnotion,,wedemonstratethepossibilityofengineeringdefectsto,surprisingly,’?,theYoung’sModulusofdefectedNWsisevenNanomaterialshaveanumberofhigh-energypartiallygreaterthanthatoftheperfectwurtzite(WZ)--dependentproperties,suchasenhancementofphenomenon.?,weexplorethematerialdesignspaceusingthetwoThissizedependenceprovidesanadditionalcontrollingaforementionedadditionaldesignparameters,thatis,,anddemonstratetailoringthematerialDefectengineeringonthenanoscaleisanotherfascinatingpropertiesbyengineeringtheircouplede?(SF),twinning,vacancies,?7fabricationprocess,whichcanmodifythemechanical,Young’sModulusofNWs,surprisingly,increasesasthedensity89,10?electrical,,althoughthecriticalnanostructures,one-dimensionalnanostructures,forexample,pressivenanowires(NWs),nanotubes(NTs),andnanobelts(NBs),??loading,,suchaslongitudinal(caxis),11,12energyharvesting,13,14sen-15,1617,18interplaybetweenSFsandfreesurfacesistheothercauseofsors,light-emittingdiodes,andhybridenergystorage19,20thise?,,tailoringandimprovingtheirproper-27ties,speci?cally,themechanicalproperties,iskeyfortheirpartialdislocations,whereasatthenanoscale,theyare?e?,theSFmonunderstandingisthat(pointsandplanar)createsastepatthesurface,changingthelocalcrystalstructure,defectsweakenthemechanicalpropertiesofnanostruc-?,2126However,recentexperimentsonGaAsNWsReceived:December13,2016epted:February10,2017compressivecriticalstressandYoung’,6Inthiscase,Published:February23,2017?2017AmericanChemicalSociety663DOI:,2,663?669ACSOmegaArticleFigure1.(a)PerfectWZstackingsequencealongthe[0001]direction,wheretheuppercaseandlowercaselettersrefertoOandZnatomsinthesamelayer,respectively.(b)ThestackingsequenceforI1-SF,wherethearrowsshowtheSFlocations.(c)LongitudinalstressdistributionalongthecaxisforaperfectNW(dottedline)andaNWwithasingledefect(solidline).(d),thedevelopedatomisticmodelisveri?:DEVELOPMENTANDreportedexperimentalandnumericalelectromechanicalproper-3,4,33?37VALIDATIONtiesofperfectZnONWs.?NumericalsimulationsofthedefectedstructureareSFs,montypesofplanardefectsinIIVIperformedbyinitiallyrelaxingtheNWfor100psatthe?28?30andIIIVIsemiconductornanostructures,arecategorizedsimulationtemperature,T=,undermicrocanonicalintotwotypes:(i)basal-planeand(ii)prismatic-(NVE).Then,theisothermal?isobaricensembleHere,wehavedevelopedanumericalmodelforthemechanics(NPT)withaNose??HooverthermostatisappliedforanotherofI1-SFinWZZnO,whichhasthelowestformationenergy,15100psto?ndthe?nalrelaxedcon?,a31??meV/unit-cellarea,amongthedierentbasal-planeSFs(I1,±1?→???,E)-SFBurgervector(bI1)inZnOis(1/3)[0110]+(1/2)[0001],whichisgeneratedbyremovinga?1?→???of±-’sModulusisestimatedby?ttingalinearWZstructurehasastackingsequenceof...AaBbAaBbAaB-expressionontheearlysectionofthestress?straincurve,?<bAaBbAa...,;,respectively,modelisimplementedinthelarge-scaleatomic/molecular38whereasI1-SFchangesthestackingsequenceto...AaB-massivelyparallelsimulator(LAMMPS)code,andatime...(Figure1a,b).Periodicboundarycon-,tomimicalongNW,-typedefectsisthelong-rangeinteractionbetweenthedefectsinainteratomicpotentialisutilizedwithBinks’?(TableS1inSupportingInformation),ethisissueandmodelasingleSF,NWsofdi?erent664DOI:,2,663?669ACSOmegaArticlelengthsaremodeledandeachrelaxedlongitudinalstress?-rangeinteractionsbetweenellarenegligibleforNWsoflength40nmandlonger(Figure1c).Here,toavoidambiguitiesincalculatingthestressusingatomisticsimulationsduetounclearde?nitionofthestructurevolumeatsuchscales,σ*σwehaveusedarepresentativestress,(=zV/atom),toillustratethee?,whichrapidlydecaytowardtheperiodicboundaries(Figure1c);thatis,attheperiodicboundaries,,alengthof40nmischosenforallsimulatedNWshere,whereastheirdiametersvaryfrom3to10nmtostudythee?,thee?ectofdefectdensityonmechanicalbehaviorisinvestigatedbyintroducingnumerousSFs,upto13,,thedistancebetweentwoadjacentSFsvariesfrom20to3nmfordi?,,wehavecalculatedtheYoung’sModulusofbulkZnOtobe146GPa,whichisincloseagreementwiththereported?experimentalvalue,≈140GPa,3941andveri?,theformationenergyofI1---cellarea,whichisingoodagreementwithdensityfunctionaltheorycalculations,15meV/unit-cellarea31(seeSupportingInformationfordetailedcalculations).The?-SFonthesize-dependentmechanicalresponseofinteractionbetweenthedefectsandsizescaleonthestructuralZnONWs.(a)Young’sModulusofperfectanddefective(singleSF)propertiesofNWsisstudiedbyintroducingasingleI1-pression/tensionvsdiameter,whichshownegligible?σthemiddleof40nmlongZnONWsofvariousdiametersandeectofSF.(b),,pressiontest,,urstoreleasetheaccumulatedelasticenergythatresultsinthestressdrop(-knownexplanationisFigureS2).Atthecriticalstress,theoriginalWZstructurebasedonthecore?shellmodel,44whereashell(outerlayers)istransformsintoagraphite-like(HX)pressivestressduetosurfacestressesandthecoreandabody-,34,36(innerlayers),inthepresenceofaSF,theNWbreaksattheSFshellcausessurfacesti?eningandincreasestheoverallYoung’(FigureS2).Incontrast,pression,westilldirection,[0001],→?45?,z,iscalculatedusingOVITOandisshowninVariationsoftheYoung’(withasingleI1-SF)pressivestrainatthedefectsurrounding,’(Figure2a),di?erencebetweenthecriticalstressesofdefectiveandperfectthecriticalstressgenerallyreducesbyintroducingaSF(FigureNWscanbejusti?edbytheinterplaybetweenthesurfaceand2b),andthise?,?erenceinthestrengthincreaseinthetotalenergydensitybecauseoftheincreasein(criticalstresses),’sModulusatatothatforalarger-diameterNW,whichisthesourceforthenanoscalewasfrequentlyreported,usingbothexperimental2,35sizedependenceofthecriticalstressdi?erencebetweenperfectandtheoreticalapproaches,4,33,42,?edexperimentally665DOI:,2,663?669ACSOmegaArticle??,z,(a)1SF,(b)3SFs,(c)6SFs,and(d)13SFsarepresented,plexityandinterferenceofstrain??ectofSFdensityonthemechanicalresponseofNWs.(a)pressiveYoung’sModulusvsdensityofSFs,indicatingthatahigherYoung’sModuluscanbeobtainedbyintroducinghigherdefectdensitiesintheNW.(b)E?ectofSFdensityonthecriticalstress,revealingdegradationofthismaterialpropertyforthetensileloading,?VNWs,48forwhichtheSFdensitydepleteswithsynthesizingnanostructureswithahigherYoung’?;however,theycouldnotcaptureengineer