When we are doing impedance measurements of solid oxides, we can find grain arc and grain boundary arc in the spectra. Usually, we use the equivalent circuit of R and CPE in parallel to fit the experimental data.
Let assume what will happen if we change the geometry of the sample. Resistance will of course change because the sample thickness and cross section area change. But how does CPE change? CPE=1/(Y0*(jw)^n). Does Y0 and n both depend on sample geometry? If yes, how do they change so that I can get a new spectra by simulation for sample with new geometry?
Hi Xin,
for me it's not so easy to reason like this but if you want in a general way:
Y0 proportional to Surface / Thickness and n depends on the charges distribution.
I suggest to read some articles of Mark E. Orazem and Bernard Tribollet
Regards,
Dear Xin,
I do not use this type of equivalent circuit element, since the topology is not really correct. Physically more correct way is to represent this type of response through Nagami-Havriliak expression for the universal response(Capacitance).
But I agree with Nour that CPE is kind of capacitance and therefore it scales with geometry as Nour points out.
I also agree with Nour that the book by M.E. Ozarem and T.Tribollet gives quite a reasonable presentation of various aspects of electrochemical impedance spectroscopy as it is understood today.
With best regards
Petr
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