Mechanical Properties of Carbon Nanotubes potx

... deformations. Mechanical Properties of Carbon Nanotubes 297Fig. 4. HREM images of bent nanotubes under mechanical duress. (a)and(b)sin-gle kinks in the middle of SWNT with diameters of 0.8and1.2nm,respectively.(c)and ... makes the mechanical properties especially interesting and importantdue to potential structural applications.1 Mechanical Properties and Mesoscopic Duality of Nanotubes The utility of nanotubes ... nanoseconds of real physical Mechanical Properties of Carbon Nanotubes 309time. This is sufficiently long by molecular standards, as is orders of magni-tude greater than the periods of intramolecular...

... synthesis of molecular carbon structures in the form of c60 and other fullerenes stimulated an intense interest in mesoscopic carbon structures. In this respect, the discovery of carbon nanotubes ... Chapter 8 Electronic Properties of Carbon Nanotubes Probed by Magnetic Measurements M. Kosaka and K. Tanigaki 76 viii Chapter 9 Optical Response of Carbon Nanotubes F. Bommeli, ... Structures of Multi-Walled and Single- Walled Carbon Nanotubes. EELS Study T. Hanada, Y. Okada and K. Yase 29 Chapter 5 Electronic Structure of Single-Walled Carbon Nanotubes K....

... Inc.ÆÀ1¼1=5boundaryisoneinwhich1in5ofthegrainboundaryatomsmatch,asshowninFig.2.8(c).Twinboundariesmayformwithincrystals.Suchboundarieslieacrossdeformationtwinplanes,asshowninFig.2.8(d).Notethattheatomsoneithersideofthetwinplanesaremirrorimages.Stackingfaultsmayalsobeformedwhentheperfectstackinginthecrystallinestackingsequenceisdisturbed,Figs2.8(e)and2.8(f).Thesemaybethoughtofastheabsenceofaplaneofatoms(intrinsicstackingfaults)ortheinsertionofrowsofatomsthatdisturbthearrangementofatoms(extrinsicstackingfaults).IntrinsicandextrinsicstackingfaultsareillustratedschematicallyinFigs2.8(e)and2.8(f),respectively.NotehowtheperfectABCABCstackingofatomsisdisturbedbytheinsertionorabsenceofrowsofatoms.2.3.4VolumeDefectsVolumedefectsareimperfectionssuchasvoids,bubble/gasentrapments,porosity,inclusions,precipitates,andcracks.Theymaybeintroducedintoasolidduringprocessingorfabricationprocesses.AnexampleofvolumedefectsispresentedinFig.2.9.ThisshowsMnSinclusionsinanA707steel.AnotherexampleofavolumedefectispresentedinFig.1.16(d).This ... model of grain growth may be developed by using an analogy of growing soap bubbles. We assume that the growth of the soap bubbles(analogous to grains) is driven primarily by the surface energy of ... lead to the growth of grains in apolycrystalline material.2.3.2 Line DefectsLine defects consist primarily of dislocations, typically at the edges of patches where part of a crystallographic...

... thedevelopment of a basic understanding of the mechanical properties of mate-rials. It is not intended to be a comprehensive review of all the differentaspects of mechanical properties; such a task would ... macroscopic level of understanding of structure [Figs 16(a)–(d)]. They are often unaware of the atomic and micro-structural constituents that can affect the mechanical behavior of materialsand of the ... treatment of the fundamen-tals of the mechanical behavior of materials. The text provides a rigorousreview of the fundamental mechanics aspects of the mechanical behavior of materials.Shackleford,...

... soaking, modulus of elasticity (MOE), modulus of rupture (MOR), and internal bond (IB) properties of the panels and compare the age effect on the physical and mechanical properties of the fiberboard. ... physical, chemical, and mechanical properties of bamboo were investigated. The study consisted of the following specific objectives. 31. To determine chemical properties of bamboo, including ... the utilization of bamboo fibers to MDF. This chapter investigated the effects of age of bamboo fibers and the resin content level on the physical and mechanical properties of the manufactured...

... Physiology Page 1 of 23 MECHANICAL PROPERTIES OF THE HEART AND ITS INTERACTION WITH THE VASCULAR SYSTEM Daniel Burkhoff MD PhD, Associate Professor of Medicine, Columbia ... Cardiac Physiology Page 2 of 23 MECHANICAL PROPERTIES OF THE HEART AND ITS INTERACTION WITH THE VASCULAR SYSTEM Daniel Burkhoff MD PhD, Associate Professor of Medicine, Columbia University ... the time course of change in ventricular mechanical properties by plotting the time course of change in the slope of the instantaneous PVR. Above, we referred to the slope of the ESPVR as an...

... showing thelinear shear creep compliance of polystyrene over a wide range of temperatures. On Mechanical properties of solid polymersConstitutive modelling of long and short term behaviour6 1 INTRODUCTIONthe ... Schematic representation of the influence of ageing time teon the yield stressand post-yield behaviour. (b) The effect of mechanical rejuvenation due to plasticcycling of polycarbonate in simple ... times are the same function of temperature. The influence of stress isquantitatively described by the Eyring theory of nonlinear flow. For polycarbonate,the applicability of time-stress superposition...

... Inc.1Overview of Crystal/Defect Structureand Mechanical Properties andBehavior1.1 INTRODUCTIONThe mechanical behavior of materials describes the response of materials to mechanical loads ... Inc.nonmetals.Ceramicsmayhaveionic,covalent,ormixedionicandcovalentbonds.Therelativelyhighcompressivestrengthsofmostceramicsmayalsobeattributedlargelytostrongionicand/orcovalentbonds.Unfortunately,however,mostceramicsarebrittleduetotheirinabilitytoaccommodatestrainsinthepresenceofcracktips(especiallyundertensileloadingwherecrackstendtoopenup).Metalsandceramicsusuallyhavelong-range,ordered,crystallinestructures.However,amorphousstructuresmayalsoformundercertainprocessingconditions.Inthecaseofcrystallinemetallicandceramicmate-rials,theatomswithineachcrystalallhavethesameorientation.Acrystal-linelattice,consistingofregularrepeatedunits(somewhatakintoLegobuildingblocksinachild’splaykit)inaregularlattice,isobserved.Eachrepeatedunitisusuallyreferredtoasaunitcell,andtheunitcellisgenerallychosentohighlightthesymmetryofthecrystal.Anexampleofatwo-dimensionalunitcellisshowninFig.1.10(a).This illustrates the two-dimensional layered structure of graphit e which isone of the allotropes of carbon. Note ... Inc.odictableofelementswasalsodevelopedinthe19thcenturybeforetheimagingofcrystalstructurewasmadepossibleafterthedevelopmentofx-raytechniqueslaterthatcentury.Forthefirsttime,scientistswereabletoviewtheeffectsofatomsthathadbeenpostulatedbytheancients.Aclearpictureofatomicstructuresoonemergedasanumberofdedicatedscientistsstudiedtheatomicstructureofdifferenttypesofmateri-als.First,itbecameapparentthat,inmanymaterials,theatomscanbegroupedintounitcellsorbuildingblocksthataresomewhatakintothepiecesinaLegoset.Thesebuildingblocksareoftencalledcrystals.However,therearemanymaterialsinwhichnocleargroupingofatomsintounitcellsorcrystalscanbeidentified.Atomsinsuchamorphousmate-rialsareapparentlyrandomlydistributed,anditisdifficulttodiscerncleargroupsofatomsinsuchmaterials.Nevertheless,inamorphousandcrystal-linematerials,mechanicalbehaviorcanonlybeunderstoodifweappreciatethefactthattheatomswithinasolidareheldtogetherbyforcesthatareoftenreferredtoaschemicalbonds.Thesewillbedescribedinthenextsection.1.3CHEMICALBONDSTwodistincttypesofchemicalbondsareknowntoexist.Strongbondsareoftendescribedasprimarybonds,andweakerbondsaregenerallydescribedassecondarybonds.However,bothtypesofbondsareimportant,andtheyoftenoccurtogetherinsolids.Itisparticularlyimportanttonotethattheweakersecondarybondsmaycontrolthemechanicalbehaviorofsomematerials,evenwhenmuchstrongerprimarybondsarepresent.Agoodexampleisthecaseofgraphite (carbon) whichconsistsofstrongprimarybondsandweakersecondarybonds(Fig.1.1).Therelativelylowstrengthofgraphitecanbeattributedtothelowshearstressrequiredtoinducetheslidingofstrongly(primary)bondedcarbonlayersovereachother.Suchslidingiseasybecausethebondsbetweenthesliding(primarybonded)carbonplanesareweaksecondarybonds.1.3.1PrimaryBondsPrimarybondsmaybeionic,covalent,ormetallicincharacter.Sincethesearerelativelystrongbonds,primarybondsgenerallygiverisetostiffsolids.Thedifferenttypesofprimarybondsaredescribedindetailbelow.1.3.1.1IonicBondingIonic...

... relativelyhigh (b1100°C), a mixture of graphitic carbon andSiC nanowires was formed because of both thecarbonization of the nanowires and the fast carbon deposition to form the carbon- like structure.4. ... formed by carbon atoms diusing into theSi NWs, CNTs could not be formed very well onthe surface of nanowires because of both thevolume change of the nanowires and breaking of the carbon network ... thecoated carbon grew to become large carbon sheets,as shown in the bottom image in Fig. 4b. Even thenanowires were completely carbonized and mixedinto a lot of carbon sheets to form a mixture of Fig....

... Basically, formost of novel materials, their mechanical properties are of great importance for their potential application. Since so,assessing the mechanical properties of such core–shellnanowires ... gaps of Ge-core/Si-shell and Si-core/Ge-shell nanowires at the level of density functional theory, where the composition is definedas the ratio of the number of atoms of the core to thenumber of ... number of atoms of core–shell nanowires are fixed to be 2524. Theunit of the length is in a˚.Table 1The optimal structural parameters of Ge-core/Si-shell nanowiresRadius of coreInnerradius of shellOuterradius...