# Relaxation times/frequencies of Polarization Mechanisms

by citw
Tags: mechanisms, polarization, relaxation, times or frequencies
P: 72
Why do polarization mechanisms decrease with frequency in the following order:

Space charge/Interface

Dipole

Ionic

Electronic

See page 3 in the attached document for reference.

Edit: corrected error in wording
Attached Files
 F. DIELECTRIC BEHAVIOR.pdf (78.8 KB, 1 views)
 Sci Advisor P: 3,267 I would rather say they decrease in that order! In general the maximal frequency depends on the inertia of the degrees of freedom. It is clear that an ion can't move as fast as an electron as it is heavier. A more elaborate argument goes like this: The degrees of freedom have characteristic frequencies at which absorption takes place. For ordinary conduction/ space charges this frequency is zero (Drude), for dipole orientation there is a range of frequencies up to the microwave and finally ionic and electronic transitions occur in the IR and UV part of the spectrum. Now the real part of the dielectric constant can be obtained from this absorptive part by a Kramers Kronig transformation.
P: 72
 Quote by DrDu I would rather say they decrease in that order! In general the maximal frequency depends on the inertia of the degrees of freedom. It is clear that an ion can't move as fast as an electron as it is heavier. A more elaborate argument goes like this: The degrees of freedom have characteristic frequencies at which absorption takes place. For ordinary conduction/ space charges this frequency is zero (Drude), for dipole orientation there is a range of frequencies up to the microwave and finally ionic and electronic transitions occur in the IR and UV part of the spectrum. Now the real part of the dielectric constant can be obtained from this absorptive part by a Kramers Kronig transformation.
The lower frequency of interface and dipole polarization, in that order, relative to ionic polarization is what I'm having trouble with. I'm not sure why interfacial polarization occurs at the lowest frequency or why dipole/orientation polarization occurs at a higher frequency than interfacial, but a lower frequency than ionic.