材料科学基础英文版课件1

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

2、zwithregularshape.Quartzwithgeometricalpolyhedronshapewascalledascrystal.Quartz3Later,allsolidswithgeometricalpolyhedronshapeweredefinedcrystal,suchassalt,calcite,magnetite.SaltCalcitemagnetiteRuby/CorundumDiamondZircon4SaltQuartzBerylRedBeryl5Thebuildingblocksofthesetwoareidentical,butdiffere

3、ntcrystalfacesaredevelopedCrystalStructureCleavingacrystalofrocksalt6Theexternalappearanceofcrystalsareallcharacterizedbyflatboundingplaneswhichintersectatcharacteristicangles.Whymanyroundedstonesandman-madecastsolidobjectswithnoexternalevidenceareobserved?Question:78DefinitionofcrystalCrystal

4、sarebuiltupofregulararrangementsofatoms,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:IdenticalSurroundingsthegroupingoflatticepointsaboutanygivenpointisidenticaltothegroupingaboutanyotherpointinthelattice.9Equivalen

5、tPoints,SpaceLatticeperiodicarrayofpointsinthreedimension——SpaceLatticeLatticePointsEquivalentPoint:Identicalpositionandidenticalsurroundingi.e.Cl-center、Na+center、betweenCl-&Na+Geometricpoint，NoweightandsizeSpacelatticewith3Dperiodrepeatingpatternisbuiltbyabstractionequivalentpointincrystalst

6、ructure,whichshows.10LatticeLattice=Aninfinitearrayofpointsinspace,inwhicheachpointhasidenticalsurroundingstoallothers.ItcanbedescribedbyassociatingwitheachlatticepointagroupofatomscalledtheMotif(Basis)CrystalStructure=Theperiodicarrangementofatomsinthecrystal.11Lattice:Periodicrepeatingarray?

7、=?=12Lattice,Basis,CrystalStructureDon'tmixupatomswithlatticepointsLatticepointsareinfinitesimalpointsinspaceAtomsarephysicalobjectsLatticePointsdonotnecessarilylieatthecentreofatoms13DifferencesofLatticeandCrystalStructureLatticeAnarra