Other Ionic Structures'

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Other Ionic Structures.
PerovskiteABO3
B-site BO6 octahedra
A-site
12 Oxygen neighbors
For perfect cube A-O/B-O v2 Goldschmidt
tolerance factor

• Flexible tolerant smaller A (A-O/B-O lt v2)
  tilting

Very large number of examples
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• Perovskite most widely studied oxide structure

• Wide range of chemistries possible
• - thousands of examples known

Unique properties of perovskites
- high Tc cuprate superconductors- Colossal
Magneto-Resistance (La,SrMnO3)- fast ion
conduction (Li, O2-), batteries, fuel cells-
mixed electronic/ionic conduction, fuel cells-
oxidation/reduction catalysts- ferroelectric /
piezoelectric ceramics (BaTiO3, Pb(ZrTi)O3)-
important mineral structure in lower mantle
(MgSiO3)- frequency filters for wireless
communications Ba(Zn1/3Ta2/3)O3
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• Dipoles in BaTiO3
• ferroelectric
• piezoelectric

• Many applications non-volatile memories
  sensors, actuators, ultra-sonic imaging

• Memories/nano-lithography

Pole sample to align dipoles
Write using nano-tips
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High Temperature SuperconductorsCuO based
Zero electrical resistance to 135K
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La3Mn3O3
each substituted Sr oxidizes Mn3 to Mn4
Replace by Sr2
mixed valent Mn show unique electronic/magnetic
properties
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ZSM-5 silicate based microporous solids
Catalysts Molecular sieves chemical separation