1. GROUP MEMBERS ABDUL MUHAIMIN BIN ABDUL HAKIM 1120251 AFIQ ARIF AMINUDDIN JAFRY1120247 AHMAD ADLI MOHAMAD HANAFI1120249 AZRAAI HAKIMI AHMAD TAMIZI1120255 MOHAMAD ZAKWAN ZULKIFLE1120239

2. Ceramic Oxide structures – oxygen anions much larger than metal cations – close packed oxygen in a lattice (usually FCC) – cations in the holes of the oxygen lattice

3. Factors that Determine Crystal Structure 1. Size of sites 2. Stoichiometry 3. Bond Hybridization

4. Size of sites Stable Structure: - Maximize the cord of nearest oppositely charged neighbours. Charge Neutrality: - Net charge in the structure should be zero. General form: AmXp CaF2: Ca2+ cation F- anions F-

5. Coordination # increases with r cation /r anion r cation / r anion Coord # < 0.1552linear 0.155 - 0.2253triangular 0.225 - 0.4144TDTD 0.414 - 0.7326OHOH 0.732 - 1.08cubic

6. Determine minimum r cation /r anion for O H site (C.N. = 6) 2r anion + 2r cation = 2a a = 2r anion 2r anion + 2r cation =2 √2r anion r anion + r cation = √2r anion r cation =(√2−1)r anion r cation /r anion = 0.141

7. Stoichiometry – If all of one type of site is full the remainder have to go into other types of sites. Ex: FCC unit cell has 4 OH and 8 TD sites. If for a specific ceramic each unit cell has 6 cations and the cations prefer OH sites 4 in O H 2 in T D

8. Bond Hybridization – significant covalent bonding – the hybrid orbitals can have impact if significant covalent bond character present – For example in SiC X Si = 1.8 and X C = 2.5 %ionic character 100 {1- exp[-0.25(X si -X C )2 ]} 11.5% ca. 89% covalent bonding both Si and C prefer sp3 hybridization Therefore in S iC get T D sites

9. -AX–Type Crystal Structures include NaCl, CsCl, and zinc blende -Cesium Chloride structure: rCs⁺/rCl⁻=0.170/0.181=0.939 So each Cs+ has 8 neighboring Cl-

10. Fluorite structure Calcium Fluorite (CaF2) cations in cubic sites UO2, ThO2, ZrO2, CeO2 antifluorite structure – cations and anions reversed

11. Perovskite Ex: complex oxide BaTiO3

12. Mechanical Properties -Very brittle in tension ( brittle fracture - limited energy absorption) - Limited load carrying capacity -The strength of ceramic materials is strongly dependent on the processing (because of introduction of strength limiting flaws) - Ceramics are usually much stronger in compression than in tension.

13. -At room T, both crystalline and amorphous ceramics fracture before plastic deformation occurs -Fracture is usually transgranular (rather than intergranular) -Cracks often grow along high density crystallographic planes (cleavage planes) ceramic metal stress strain Ceramics don’’t ”dent””

14.  Brittle ceramic materials are usually tested in bending(not in tension as are most metals), because: • Sample preparation is easier Significant difference in results for testing in tension, compression and bending  MOR is calculated as the “maximum fiber stress” on the tension side at failure (strength parameter) For a rectangular cross-section:For a circular cross-section: σ= 3FL/2bh²ε=12xr/L² σ=3FL/πr²

15.  Brittle materials can have their fracture strength increased by reducing the depth and sharpness of surface flaws through careful polishing or etching.  Abrasion of the surface in such a way as to introduce flaws has just the opposite effect  Transformation toughening  local stress induces transformation of dispersed second phase  squeezes crack shut (closure)  Microcracks  very fine cracks (much smaller than critical size) blunt tip of

16.  At room T - rarely occurs  At high T - deformation can occur – Creep (usually loaded in compression) – Crystalline ceramics depend on dislocation movement(difficult) – Noncrystalline ceramics above Tg exhibit viscous flow(like any liquid) – Mixtures creep as glassy materials (viscous flow)

17.  Low stress crack growth without cycling – occurs in water containing environments –occurs at room temperature –caused by water reacting with oxide network - Si -O – Si - O HH - Si - OH OH - Si

18.  Annealed No residual stresses at room temperature large and sharp segment breakage  Tempered Surface quenched below Tg Slow cooled to room temperature Surface residual compressive stress, core residual tensile stress finely fragmented and dull breakage.  Laminated: Two ordinary layer of annealed glass with a central layer if polymer.

19. 1. Whitewares (pottery, tableware, sanitary ware, wall tile) 2. Refractories (materials for lining furnaces and processing vessels) 3. Structural clay products (brick, pipe, construction tile) 4. Glass (subcategories of flat glass, container glass, optical and fiber) 5. Abrasives 6. Cements and plaster 7. Porcelain enamel 8. Technical or fine ceramics  – electronic ceramics  – structural ceramics  – specialized technical applications (bio applications)