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Ceramic Materials — Structures and Properties

Ceramic Materials — Structures and Properties. Ceramic Materials 陶瓷材料. Inorganic materials 無機材料 Nonmetallic materials 非金屬材料 Most ceramics are compounds between metallic and nonmetallic elements Composed of at least two elements , and often more

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Ceramic Materials — Structures and Properties

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  1. Ceramic Materials — Structures and Properties

  2. Ceramic Materials 陶瓷材料 • Inorganic materials 無機材料 • Nonmetallic materials 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 ionic to totally covalent

  3. Electronegativity 電負度、陰電性

  4. - - - - - - + + + - - - - - - stable stable unstable Stable and unstable cation-anion coordination configuration Cations are ordinarily smaller than anions cation 陽離子 anion 陰離子

  5. Coordination Number 配位數 Coordination Number 配位數 2 3 4 6 8 Cation-Anion Radius Ration rC/rA <0.155 0.155-0.225 0.225-0.414 0.414-0.732 0.732-1

  6. rC/rA > 1 配位數12

  7. Crystal Structures • AX Type • Rock Salt Structure 岩鹽結構 • Cesium Chloride Structure 氯化銫結構 • Zinc Blende (Sphalerite) Structure 閃鋅礦結構 • AX2 Type • Fluorite Structure 螢石結構、氟石結構 • ABX3 Type • Perovskite Structure 鈣鈦礦結構 • AB2X4 Type • Spinel Structure 尖晶石結構

  8. Rock Salt Structure 岩鹽結構 • NaCl, MgO, MnS, LiF, FeO rNa+ = 0.102 nm rCl  = 0.181 nm rNa+/rCl = 0.564

  9. Cesium Chloride Structure 氯化銫結構 rCs+ = 0.170 nm rCl  = 0.181 nm rCs+/rCl  = 0.939 • CsCl

  10. Zinc Blende Structure 閃鋅礦結構 • ZnS, ZnTe, SiC, ZnO rZn2+ = 0.074 nm rO2= 0.140 nm rZn+2/rO2  = 0.529

  11. Fluorite Structure 螢石結構 • CaF2, ZrO2, UO2, PuO2, ThO2 rCa2+ = 0.100 nm rF= 0.133 nm rCa+2/rF = 0.8

  12. Perovskite Structure 鈣鈦礦結構 • BaTiO3, SrZrO3, SrSnO3

  13. Interstitial position填隙位置、間隙位置 • Tetrahedral position 四面體位置 • Octahedral position 八面體位置 close-packed structure 最密堆積結構、緊密堆積結構

  14. A sites c B sites A sites A a B C Crystal structure • Hexagonal Close-Packed (HCP) 六方最密堆積 • ABAB... Stacking Sequence • Face-Centered Cubic (FCC) 面心立方 • ABCABC... Stacking Sequence

  15. Determine Crystal Structures • Stoichiometry 化學計量 • Charge Neutrality • Cation-anion radii ratios (coordination number) • Covalent character

  16. Ceramic Density Computation Number of formula units/unit cell AC: atomic weight of cation AA: atomic weight of anion VC: Volume of unit cell NA: Avogadro’s number

  17. Silicate Ceramics 矽酸鹽陶瓷

  18. Silica 矽石、二氧化矽 • Crystalline structure of Silica • Quartz 石英 • Cristobalite (Crystobalite) 白矽石、方矽石 • Tridymite 鱗石英、鱗矽石 • The strong Si-O bond leads to a strong, high melting temperature (1710C)

  19. Cristobalite (Crystobalite) 白矽石、方矽石

  20. Silica Glass 矽石玻璃 • fused silica or vitreous silica 熔凝矽石或玻化矽石 • B2O3 and GeO2 • Network former • CaO and Na2O • Network modifier • TiO2 and Al2O3 • Intermediate • Modifiers and Intermediates lowers the melting point and viscosity of a glass

  21. Crystalline silicon dioxide Noncrystalline silicon dioxide

  22. Silicate 矽酸鹽

  23. Two-dimensional silicate sheet structure (Si2O5)2

  24. Layered Silicates • Can change the counterions (相對離子) • this changes layer spacing • the layers also allow absorption of water • Mica 雲母KAl3Si3O10(OH)2 • Bentonite 膨土、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 supply

  25. Structure of kaolinite clay高嶺黏土

  26. Carbon 碳 • Diamond 鑽石 • metastable state 介穩態、準穩態 • Graphite 石墨 • Fullerene 芙、芙樂、富勒、芙樂烯、富勒烯 • C60 • Buckminsterfullerenes巴克明斯特芙樂烯 • Buckyball 巴克球

  27. Diamond cubic crystal structure

  28. Structure of Graphite

  29. Structure of a C60 Molecule

  30. Structure of a Carbon Nanotube

  31. Imperfections in Ceramic • Imperfection 缺陷 • Electroneutrality 電中性 • Atomic Point Defect • Vacancy 空位 • Interstitial 填隙、間隙 • Defect Structure • Frenkel defect 夫倫克耳缺陷 • Schottky defect 肖特基缺陷 • Stoichiometry or Nonstoichiometry

  32. Defect Structure Schottky defect Frenkel defect

  33. Impurities in Ceramics • Electroneutrality 電中性 • Solid solution 固溶體 • substitutional type • interstitial type

  34. Diffusion in Ionic Materials • Diffusion in ionic materials usually occurs by a vacancy mechanism • Electroneutrality 電中性

  35. Ceramic Phase Diagrams MgO-Al2O3

  36. Brittle Fracture of Ceramics • brittle fracture 脆性斷裂 • plastic deformation 塑性形變 • fractography 斷口形像學 • crack 裂痕、裂紋、裂縫 • branch or bifurcate 分叉

  37. Stress-Strain Behavior • Stress 應力 • Strain 應變 • flexural strength 抗彎強度、抗撓強度、撓曲強度 • modulus of rupture 破壞模數 • fracture strength 破裂強度 • bend strength 彎曲強度

  38. Plastic Deformation • Crystalline ceramics • Noncrystalline ceramics • Viscosity 黏度、黏性

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