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Here are some quick questions: |
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The answers are sometimes (and possibly only indirectly)
contained in the links. |
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2.1.2 Frenkel Defects |
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Why do we need
"Frenkel" and
"Schottky" defects besides vacancies, self-interstitials and
their agglomerates? |
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Draw a schematic picture of a crystal with
"Frenkel" and "Schottky" defects. What kind of "conservation laws" do
you have to consider, and why does that lead to a
fundamental difference
between the two defect kinds? |
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What kind of charge would "the" vacancy
carry in a NaCl crystal? (Consider only the realistic case). |
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Give some crystals where
Frenkel disorder
prevails. |
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Give an (approximate)
equation for the
concentration of Frenkel defects an discuss the important terms |
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2.1.3 Schottky Defects and 2.1.4. Mixed
Defects |
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What, quite generally, is the
Debye
length? |
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How does the Debye
length come into
consideration when discussion Schottky defects (and Frenkel defects)? |
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If the formation enthalpies of two defect kinds
differs by roughly ...???...eV, one defect type will be dominating and
the other one can be neglected. |
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Why do we usually consider either Schottky or Frenkel defects in ionic crystals but not
mixed defects? For the
answer check this exercise. |
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Can you predict for a given ionic crystal which
kind of defect type (Schottky or Frenkel)
will be
prevalent? |
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Discuss the details in the following set
of equations: |
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ß
[NaNa] · [Vi]
[Nai] · [VNa] |
= const = exp |
GReaction
kT |
ß
| cV(C) · ci(C) |
= |
N'
N |
· exp – |
HFP
kT |
ß
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Derive in an equivalent way the final relation for
Schottky defects: |
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| cV(A) · cV(C) |
= exp – |
HS
kT |
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© H. Föll (Defects - Script)
2.2.2 Local and Global Equilibrium 
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