Constant phase element is used as an unorthodox electrical circuit element mainly to model the behavior of a double layer, that is an imperfect capacitor and it is widely used in for fitting EIS data.
As per my knowledge and literature, the CPE is named so as its phase angle is independent of the frequency, i.e., it is constant. On the contrary, even the capacitor and inductor have their phase angle -90 deg. and +90 deg., respectively which is absolutely independent of frequency.
Then why its the CPE which has been named with the word "constant"? Is there anything else which I have skipped or not aware of ? I am looking for this answer.
Thanks
The constant phase element models in a simple way non-ideality of real capacitors, In practice the phase jump is close but different from 90 degrees. Never thought that way, but one could say that the ideal capacitor is just a particular case of CPE where the phase angle is -90°.
Marco Asa Yes it is right.
The expression of the impedance of a CPE is:
Z =1/Q*(j*2*pi*f)^alpha
when alpha is equal to 1 the expression of the impedance of a CPE is the same as an ideal capacitor.
Dear Sanjeev Kumar!
To my mind, the word "constant" is added for underlying that CPE is a more general term than capacitors and inductors.
For example, the resistance (which also has a frequency-independent phase equal to zero) could be considered as impedance with zero imaginary part. However, historically term resistance was introduced more early (1826) than more general term impedance (1886), and we still use it for defining frequency-independent impedance with zero imaginary part.
Or it like complex and real numbers. When we need to emphasize that we deal with complex numbers with zero imaginary parts we use the term "real number", and otherwise we use the generic term "complex number".
Sincerely,
Daniil D. Stupin
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