Ceramic Structures

1
Ceramic Structures

• 2 or more components trading electrons to make a
  more stable structure
• More than one atom routinely in the crystal
  structure
• Usually a different bonding scheme than in metals
• Table 13.1 Relative ionic character of ceramic
  materials

2
Relative Size and Coordination

• The relative sizes of cation and anion undergoing
  ionic bonding are important in defining what is
  stable
• Coordination The number of neighbor atoms
  participating in the ionic bond with a single
  atom
• Coordination s range from 2-12

3
Crystal Structures of Ceramics

• NaCl (Rock Salt)
• CsCl (Cesium Chloride)
• Zinc Blende
• Non AX Ceramics
• Abx Fluorites
• ABC Titanates

4
Ceramic Lnks to Metal Structures

• Substitutional Defects
• Interstitials
• Octahedral
• Tetrahedral
• Crystal Density Calculations

5
Silicon Ceramics

• Silica (SiO2)
• SiO4-4 tetrahedron
• Silicates
• Mg Silicates, Na Silicates
• Mg, Ca, Na are Network modifiers to the silicate
  structure

6
Carbon

• Carbon as a ceramic is a polymorphic structure
  (more than one form)
• Diamond
• Zinc Blende structure with only carbon in the
  structure
• under instances of high pressure and extreme
  pressures will form
• Graphite (more stable)
• HCP based structure

7
Other unique forms of Carbon

• Fullerene structures
• All carbon forms with huge levels of porosity
  within (a big soccer ball cage-like structure on
  the surface)
• Buckminsterfullerenes
• Unique in terms of potential for catalysis

8
Conclusions

• Ceramics have similar structural considerations
  to metals
• Discussed in terms of constituents, coordination
  , crystal structure and density calculations.