材料科学基础英文版课件

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1、Chapter1FundamentalConceptsofCrystal11)DefinitionofCrystal1-1.BasicConceptsofCrystalWhatisCrystal？CrystalandAmorphous2Peoplerealizedthattherearetwokindsofmineralinnature:CrystalandAmorphous.Aretheresomecommonnessforcrystals?Regularexternalshapes,flat-geometricfaceTh

2、ecrystalfirstlyfoundwasquartzwithregularshape.Quartzwithgeometricalpolyhedronshapewascalledascrystal.Quartz3Later,allsolidswithgeometricalpolyhedronshapeweredefinedcrystal,suchassalt,calcite,magnetite.SaltCalcitemagnetiteRuby/CorundumDiamondZircon4SaltQuartzBerylRed

3、Beryl5Thebuildingblocksofthesetwoareidentical,butdifferentcrystalfacesaredevelopedCrystalStructureCleavingacrystalofrocksalt6Theexternalappearanceofcrystalsareallcharacterizedbyflatboundingplaneswhichintersectatcharacteristicangles.Whymanyroundedstonesandman-madecas

4、tsolidobjectswithnoexternalevidenceareobserved?Question:78DefinitionofcrystalCrystalsarebuiltupofregulararrangementsofatoms,moleculesorionsinthreedimensions.晶体是内部质点在三维空间呈周期性重复排列的固体；或者说，晶体是具有格子构造的固体。82)SpaceLatticeandEquivalentPointsEquivalentPoint:IdenticalSurroundi

5、ngsthegroupingoflatticepointsaboutanygivenpointisidenticaltothegroupingaboutanyotherpointinthelattice.9EquivalentPoints,SpaceLatticeperiodicarrayofpointsinthreedimension——SpaceLatticeLatticePointsEquivalentPoint:Identicalpositionandidenticalsurroundingi.e.Cl-center、

6、Na+center、betweenCl-&Na+Geometricpoint，NoweightandsizeSpacelatticewith3Dperiodrepeatingpatternisbuiltbyabstractionequivalentpointincrystalstructure,whichshows.10LatticeLattice=Aninfinitearrayofpointsinspace,inwhicheachpointhasidenticalsurroundingstoallothers.Itcanbe

7、describedbyassociatingwitheachlatticepointagroupofatomscalledtheMotif(Basis)CrystalStructure=Theperiodicarrangementofatomsinthecrystal.11Lattice:Periodicrepeatingarray?=?=12Lattice,Basis,CrystalStructureDon'tmixupatomswithlatticepointsLatticepointsareinfinitesimalpo

8、intsinspaceAtomsarephysicalobjectsLatticePointsdonotnecessarilylieatthecentreofatoms13DifferencesofLatticeandCrystalStructureLatticeAnarra