I did a room temperature impedance measurement on my pellet.When I try to do the fitting using the two resistors and constant phase elements in parallel,I do not get a good for due to the tail at the lower frequencies. As,I am new to the field,it would be very helpful if anyone can help me with the equivalent circuit for this plot.the tail starts at 1e4 Hz
There's a fair chance your sample is not sufficiently stable. Try K-K transform if you can, if not, perhaps try running back to back EIS spectra (very quickly and use the same DC offset vs. ref, not Eoc because if the Eoc has shifted you'll end up making a different measurement).
Thank you Jacob Ketter.
I have repeated the measurements as mentioned by you but it results in the same plot.it is worth to mention that I have done temperature dependent scans as well and they show the same tail. Also my plot is different for 298K after cooling and heating operation.Also the pellet is not sintered as it looses lattice water if heated above 120C.
experiment details
Frequency range:- 1Mhz to 0.1hz
Temperature program::- 298K to 228K (cooling) followed by 228to348K(heating) finally 348K to 298K.
Do the Lissajous seen while collecting data seem linear (assuming you can see them)? i.e. is it a straight line or nice oval? Any time I've ever seen that type of behavior has been from invalid data. (There's far more EIS data out there that I haven't seen than have, but I have seen data like that and it's been invalid, typically not stable but could also be non-linear.)
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