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27 Cards in this Set
- Front
- Back
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System
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Material under consideration.
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Component
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Species that make up the system.
Pure metal or compound. |
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Phase
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A portion of the system which has uniform properties.
Homogeneous portion. |
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Equilibrium
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Terminal (lowest energy) states that systems will evolve to over long time.
Stable states. |
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Gibbs Phase Rule
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P + F = C + N
P = number of phases F = number of degrees of freedom C = number of components N = number of noncompositional variables |
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Comparing overall composition and liquid & solid composition.
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Overall composition remains the same but liquid and solid composition may change.
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Solidus and liquidus lines
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Compositions of the liquid and solid phases that are in equilibrium with each other at T.
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Reading Cu/Ni binary phase diagram
(EXAMPLE 1) |
Lecture 20
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What are ceramics characterized by?
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Inter metallic bonds that are ionic or predominantly ionic.
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Structure of ceramics depends on...
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Cation to anion radii
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What makes a stable structure?
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Ones where cations and anions are in contact.
If the cation is too small, the anions may slip and re-arrange. |
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Relate geometry with coordination number
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2 = linear
3 = triangular 4 = tetrahedral 6 = octahedral 8 = CsCl |
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Derive rc/ra for all coordination numbers
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Recitation 20
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Rock Salt
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AX, FCC, CN = 6(+), 6(-)
Example: NaCl |
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CsCl
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AX, SC, CN = 8(+), 8(-)
Example: CsCl |
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Zincblende
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AX, FCC, CN = 4(+), 4(-)
Example: ZnS |
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Fluorite
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AmXp, SC, CN = 8(+), 4(-)
Example:CaF2 |
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Perovskite
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AmBnXp, FCC, CN = 12(A), 6(A), 6(-)
Example:BaTiO3 |
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Relationship between rc, ra and a
Rocksalt |
a = 2 [ra + rc]
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Relationship between rc, ra and a
CsCl |
a = 2/sqrt(3) [ra + rc]
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Relationship between rc, ra and a
Fluorite |
a = 4/sqrt(3) [ra + rc]
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Relationship between rc, ra and a
Zincblende |
a = 4/sqrt(3) [ra + rc]
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Relationship between rc, ra and a
Perovskite |
a =
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Density of ceramics
(Formula) |
Density = Number of formula units in unit cell * (Sum of all cation atomic masses + Sum of all anion atomic masses) / Vc * Na
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APF
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APF = total vol of cations + total vol of anions/ Vc
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Values of n'
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NaCl = 4
CsCl = 1 ZnS = 4 Fluorite = 4 and 8 Perovskite = 1 1 and 3 |
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Eutectic point
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The point at which all three phases co-exist simultaneously at the same temperature.
Draw diagram with Lamellar structure and liquid. |
