Dielectric Relaxation in Materials with a Single Time Constant

2 Dielectric Relaxation in Materials with a Single Time Constant 

When an electric field E is applied to an insulating material, the resulting polarization P may be divided into two parts according to the time constant of the response  

An almost instantaneous polarization due to the displacement of the electrons with respect to the nuclei. This defines the high-frequency dielectric constant e related to the refractive index. 

The time constant of this process is about 10 s and therefore occurs in the UV region of the electromagnetic spectrum. Ionic vibrations have a time constant which usually occurs in the infrared and are also therefore instantaneous as far as electrochemical experiments are concerned. 

A time-dependent polarization P (0 due to the orientation of dipoles in the electric field. If the field remains in place for an infinitely long time, the resulting total polarization Pj defines the static dielectric constant e/. 

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