间隙位置Tetrahedralposition四面体位置Octahedralposition八面体课件.ppt

1、Ceramic Materials Structures and PropertiesCeramic Materials 陶瓷材料陶瓷材料 Inorganic materials 無機材料無機材料 Nonmetallic materials 非金屬材料非金屬材料 Most ceramics are compounds between metallic and nonmetallic elements Composed of at least two elements,and often more Atomic bonding in ceramics ranges from purely ion

2、ic to totally covalent22ionic character1ABXXe MaterialIonic CharacterCaF289%MgO73%NaCl67%Al2O363%SiO251%Si3N430%ZnS18%SiC12%Electronegativity 電負度電負度、陰電性陰電性Stable and unstable cation-anion coordination configuration-+unstable-+stable-+stableCations are ordinarily smaller than anionscation 陽離子陽離子anion

3、 陰離子陰離子Coordination Number 配位數配位數23468Coordination Number 配位數配位數Cation-Anion Radius Ration rC/rA 1 配位數配位數12Crystal Structures AX Type Rock Salt Structure 岩鹽結構岩鹽結構 Cesium Chloride Structure 氯化銫結構氯化銫結構 Zinc Blende(Sphalerite)Structure 閃鋅礦結閃鋅礦結構構 AX2 Type Fluorite Structure 螢石結構螢石結構、氟石結構氟石結構 ABX3 Type

4、Perovskite Structure 鈣鈦礦結構鈣鈦礦結構 AB2X4 Type Spinel Structure 尖晶石結構尖晶石結構Rock Salt Structure 岩鹽結構 NaCl,MgO,MnS,LiF,FeOrNa+=0.102 nmrCl =0.181 nmrNa+/rCl=0.564Cesium Chloride Structure 氯化銫結構 CsClrCs+=0.170 nmrCl =0.181 nmrCs+/rCl =0.939Zinc Blende Structure 閃鋅礦結構 ZnS,ZnTe,SiC,ZnOrZn2+=0.074 nmrO2=0.140

5、nmrZn+2/rO2 =0.529Fluorite Structure 螢石結構 CaF2,ZrO2,UO2,PuO2,ThO2rCa2+=0.100 nmrF=0.133 nmrCa+2/rF=0.8Perovskite Structure 鈣鈦礦結構 BaTiO3,SrZrO3,SrSnO3Interstitial position填隙位置、間隙位置填隙位置、間隙位置 Tetrahedral position 四面體位置四面體位置 Octahedral position 八面體位置八面體位置close-packed structure 最密堆積結構、緊密堆積結構最密堆積結構、緊密堆積結構

6、Crystal structure Hexagonal Close-Packed(HCP)六方最密堆積六方最密堆積 ABAB.Stacking Sequence Face-Centered Cubic(FCC)面心立方面心立方 ABCABC.Stacking SequencecaA sitesB sitesA sitesABCDetermine Crystal Structures1.Stoichiometry 化學計量化學計量l Charge Neutrality2.Cation-anion radii ratios(coordination number)3.Covalent charac

7、terCeramic Density ComputationAACNV)AA(nCNumber of formula units/unit cellAC:atomic weight of cation AA:atomic weight of anion VC:Volume of unit cellNA:Avogadros numberSilicate Ceramics 矽酸鹽陶瓷矽酸鹽陶瓷Silica 矽石、二氧化矽矽石、二氧化矽 Crystalline structure of Silica Quartz 石英石英 Cristobalite(Crystobalite)白矽石、方矽石白矽石、方

8、矽石 Tridymite 鱗石英鱗石英、鱗矽石鱗矽石 The strong Si-O bond leads to a strong,high melting temperature(1710 C)Cristobalite(Crystobalite)白矽石、方矽石白矽石、方矽石Silica Glass 矽石玻璃矽石玻璃 fused silica or vitreous silica 熔凝矽石熔凝矽石或玻化矽石或玻化矽石 B2O3 and GeO2 Network former CaO and Na2O Network modifier TiO2 and Al2O3 Intermediate Mo

9、difiers and Intermediates lowers the melting point and viscosity of a glassCrystalline silicon dioxideNoncrystalline silicon dioxideSilicate 矽酸鹽矽酸鹽Two-dimensional silicate sheet structure(Si2O5)2 Layered Silicates Can change the counterions(相對離子相對離子)this changes layer spacing the layers also allow a

10、bsorption of water Mica 雲母雲母 KAl3Si3O10(OH)2 Bentonite 膨土膨土、火山黏土火山黏土 used to seal wells packaged dry swells 2-3 fold in H2O pump in to seal up well so no polluted ground water seeps in to contaminate the water supplyStructure of kaolinite clay高嶺黏土高嶺黏土Carbon 碳碳 Diamond 鑽石鑽石 metastable state 介穩態、準穩態介穩

11、態、準穩態 Graphite 石墨石墨 Fullerene 芙芙、芙樂芙樂、富勒富勒、芙樂烯芙樂烯、富勒烯富勒烯 C60 Buckminsterfullerenes 巴克明斯特芙樂烯巴克明斯特芙樂烯 Buckyball 巴克球巴克球Diamond cubic crystal structureStructure of GraphiteStructure of a C60 MoleculeStructure of a Carbon NanotubeImperfections in Ceramic Imperfection 缺陷缺陷 Electroneutrality 電中性電中性 Atomic

12、Point Defect Vacancy 空位空位 Interstitial 填隙填隙、間隙間隙 Defect Structure Frenkel defect 夫倫克耳缺陷夫倫克耳缺陷 Schottky defect 肖特基缺陷肖特基缺陷 Stoichiometry or NonstoichiometryDefect StructureFrenkel defectSchottky defectImpurities in Ceramics Electroneutrality 電中性電中性 Solid solution 固溶體固溶體 substitutional type interstitia

13、l typeDiffusion in Ionic Materials Diffusion in ionic materials usually occurs by a vacancy mechanism Electroneutrality 電中性電中性Ceramic Phase DiagramsMgO-Al2O3Brittle Fracture of Ceramics brittle fracture 脆性斷裂脆性斷裂 plastic deformation 塑性形變塑性形變 fractography 斷口形像學斷口形像學 crack 裂痕裂痕、裂紋裂紋、裂縫裂縫 branch or bifurcate 分叉分叉Stress-Strain Behavior Stress 應力應力 Strain 應變應變 flexural strength 抗彎強度抗彎強度、抗撓強度、抗撓強度、撓曲強度撓曲強度 modulus of rupture 破壞模數破壞模數 fracture strength 破裂強度破裂強度 bend strength 彎曲強度彎曲強度Plastic Deformation Crystalline ceramics Noncrystalline ceramics Viscosity 黏度黏度、黏性黏性