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Here are some values for dielectric constants: |
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First, some of themore interesting materials with electronic
polarization at work, at least to some noticeable extent. |
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Static er for some semiconductors.
| Covalent bonding |
Covalent and ionic bonding |
Electronic polarization is the main mechanism |
Mix of electronic and ionic polarization | C |
5.7 | ZnO | 4.6 | Si |
12.0 | ZnS | 5.1 | Ge |
16.0 | ZnSe | 5.8 | SiC |
6.7 | CdS | 5.2 | GaP |
8.4 | CdSe | 7.0 | GaAs |
10.9 | BeO | 3.0 | InP |
9.6 | MgO | 3.0 |
The numbers are from "Solid State Physics" of Ashcroft / Mermin (an advanced text book).
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Next, some numbers for ionic crystals.
Besides the static er(w = 0), the value er(w = ¥) for very high frequencies
is also given. This means that after ionic polarizaton "dies out", there is still some electronic polarization
left. |
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Static and high-frequency er for some ionic crystals |
Crystal |
er(w = 0) |
er(w = ¥) |
LiF | 9.01 | 1.96 |
NaF | 5.05 | 1.74 |
KF | 5.46 | 1.85 | LiCl |
11.95 | 2.78 | NaCl | 5.90 | 2.34 |
KCl | 4.84 | 2.19 | LiBr |
13.25 | 3.17 | NaBr | 6.28 | 2.59 |
LiI | 16.85 | 3.80 | NaI |
7.28 | 2.93 |
The numbers are from "Solid State Physics" of Ashcroft / Mermin (an advanced text book).
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© H. Föll (Electronic Materials - Script)