In general, the intersection of the high frequency side semicircle to the real axis gives the bulk resistance. This is quite easy, if the center of the semicircle lies on the real axis. But in most of the cases, it is not a perfect semicircle and center lies either above or below the real axis. In this case, how can one obtain the bulk resistance by plotting the data in origin software? Or it is just taking the minimum of the semicircle to get the value of bulk resistance?
First of all non-ideal (Depressed semicircle) or deviation from Debye behavior and origin of different relaxations can be due to Grain orientation, Grain boundary, Sub-grain boundary, Electrode effect and also be due to Interface functional groups. Usually multiple relaxations can be associated with polycrystalline structure too.
In liquids usually there is one central relaxation which exhibits distribution due to the changes in the local environment. In polymers there can be relaxation phenomena widely decoupled from each other as e.g. main chain relaxation (alpha) and side chain relaxation (beta). The degree of decoupling may depend on the temperature (they tend to merge at high temperature).
You can observe these multiple relaxation from Cole-Cole plot, but some times this plot can't give you sufficient information. Then you can try Modulus plane plot or comparison between imaginary parts of M'' and Z''.
In your case, in my opinion three relaxation is dominant.
one is electrode/interface effect (Lower frequency), second is grain boundary (Intermediate frequency) and third one is bulk or grain(higher frequency).
Values of resistance can be calculated directly from Impedance data or you can fit these curves with some software e.g. Z-view or do simulation .
Actually the value of capacitance and resistance both, obtained from fitting actually gives us clue about the different electroactive regions. e.g. value of capacitance for bulk or grain( ~10^-12F) , Grain boundary (~10^-12F,10^-11F,10^-10F) and electrode or interface effect should be (~10^-10F,10^-9F,10^-8F).
I hope my answer will serve your purpose.
Further you can look at these research papers, hope these papers will be helpful for you.
1) http://apl.aip.org/resource/1/applab/v101/i2/p023114_s1?isAuthorized=no
2) http://apl.aip.org/resource/1/applab/v101/i25/p253104_s1?isAuthorized=no
Cheers!
Thanks Dr Rasool for your nice explanation.
What exactly I need to determine is the ionic conductivity of a polymeric film.
For this we need to determine the bulk resistance of the sample.
We measure the impedance by sandwiching the film between two stainless steal disc electrodes.
How can I calculate this by ploting the data in ORIGIN ?
you can find the bulk resistance of the polymer film in Origin by extrapolating the spike portion to the x axis.The intercept of the spike portion with the x axis.
The resistance can be calculated from Nyquist Plot i.e. Z'' = R/2
This article will help you to find the resistance from impedance data
https://www.researchgate.net/publication/251617356_charge_conduction_and_relaxation_in_MoS2_nanoflakes_synthesized_by_simple_solid_state_reaction?ev=prf_pub
Article Charge conduction and relaxation in MoS2 nanoflakes synthesi...
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