I am using EIS to determine the impedance for a coating consist of Acrylic/silicone with various types of nanoparticles, but I am facing a problem with understand what the meaning of Nyquist diagrams.
If anyone can recommend from where I can read about the different between the Nyquist diagram that have one semicircle or two.
Thank you prof.Roque-Malherbe
The paper was so good and I got a lot of information about how the Nyquist plot generated.
But in the other hand i still have a lot of questions about how i can know the meanings behind each shape that could Nyquest plot take after testing i.e number of semicircles
and the meaning of random curve
I would add another publication, namely "Electrochemical Impedance Spectroscopy" by Mark E. Orazem and Bernard Tribollet (Wiley 2008). My personal view is that Nyquist type representation of the measured electric response is quite useless, since it "hides" the information that is there. Try to plot both parts of the response as log Z1(w) and log Z2(w) versus log w. My expectation is that you will see what can be defined as bulk response (higher frequencies) and near interface region at low frequencies (two semicircles on Nyquist plot). One of them can be most probably identified with your coating film and in that case, the low frequency real part of the impedance is your resistance of the coating. You might also consult United State Patent n. 5 627 479 (May 6, 1997). With best regards
Petr
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