It is possible that the increase of higher frequency limit by increasing the thickness of sample and decreasing the electrode area.

Dear Santosh

The negative points are probably an artifact due to either your potentiostat or perhaps your reference electrode.  You could test whether it is your potentiostat by measuring a resistor of the same value as your solution resistance, 10 or 11 ohms from your bode plot at high frequency and if you get similar behavior then it is your potentiostat.

Best regards

Dave

There are two kinds of resaon for "negative resistance"

Firrst one due to equipment - "reference resistor" that is assuned to be the ideal one is not really i.e. it has frequency dependence of condaction.

According to your picture It is the case,

Second one related to Krames-Kronig relationship. If imgionary part variers (layers, frequency dependece of dielectric constsnt epsilon, etc) then real part HAS TO be changed. sometimes in negative direction. But it is necessary to underatand that spectrum is kept between origin (due to cell capacity. high-freqyency limit) and dU/dI for staedy state U-I curve (low frequency limit). Between these edges can be a lot of interesting

Wishes ;)

Dear Santosh,

looking at your data, it looks to me that all the data above 10^4 Hz are suspect. My guess is also that you measure the effect of stray impedances that are not properly compensated for. How serious these effects are, depends on the instrument you use and on the leads-sample configuration. The best way to deal with these systematic error effects is to compensate them by measurement of three "known" elements - SHORT, OPEN and LOAD (usually a ideal/known resistor, "close" in value to your sample).

Agilent Technologies have so far the best compensation routines, that can be an integral part of the impedance measurement itself . One can of course write down (as we did )  one's own program when analysing the raw impedance data, but that may take a bit of time. Please, consult the following :

Agilent Technologies Impedance Measurement Handbook (July 2006) that you can get from their web site.

Challenges and solutions for Impedance Measurements - 201409 - Keysight Technologies

My further advice would be to always look at the real and imaginary part of the measured Impedance (supplemented through trivial transform in order to obtain also the real and imaginary part of the measured complex Capacitance). In these two representations, the response of the material and the possible effects of systematic errors are seen most clearly.  The plots of the kind -  real versus imaginary part of the measured impedance ( Bode plot ?) show nothing useful.

With best regards

Petr

1. необходимо измерить вольтамперную кривую и определить в каком месте вы находитесь.

2. необходимо измерить синусоиды U~t и I~t.

из этих графиков Вам всё станет ясно ;)