Warburg element can be identified by observation of complex impedance plots. If it consists of a line intersecting the x-axis making an angle of 45. It is always present in polymer electrolytes. In such system dynamics is under diffusion control, i.e. charge transport in the bulk of the sample is slower than the charge transport at electrode-electrolyte interface. Much details can be found in a book by J. R. Macdonald on Impedance Spectroscopy.

Thank you for the reference. Well even I am sure that Bode plot is indeed a proof for the presence of a Warburg element. Is there any other way to ascertain the presence of such element ?

your question needs a bit clarification about what you are expecting? Since Warburg impedance occurs at lower frequencies, so you also need to decide do you really need to go down to such lower frequencies?.

To elaborate it further, Due to some bizarre results in Nyquist plot analysis from the equivalent circuit at higher temperatures, I wanted to reconsider the circuit design.

I suspected tentative diffusion behaviour in the turbid matrix of my sample at higher temperature and used the Warburg element (after due confirmation from Bode plot) and then better fitting curves were obtained.

I work in the frequency range of 1MHz to 0.1 Hz . I was not aware of such specific occurence of Warburg impedance. I made the consideraton taking into account the turbidity of the sample and the bizzare behaviour at higher temperatures which more or less indicates about a suspected Warburg element. Hope i am correct in my analysis.

Indeed, EIS is itself is a bizarre technique. Warburg impedance is more prominent in Nyquist plot. Nowadays, Nyquist plot is more popular due to its simplicity, however, in energy cell fields Bode's plot is valued because it contains the frequency information. Bode's plot can be easily fit into circuit, misfits are more prominent in Nyquist plots. See, if the tale in lower frequency (Nyquist plot) is 45 degree angle then it's consider as Warburg impedance. If the tale is flat or at different angle, then it is different and difficult to explain and won't be fit any ways. It seems because of higher temperature, your surface properties change. Just to tell you, EIS is not an easy technique specially in terms of interpretation...you need a lot more experiements to get some thing reasonable and more meaningful from EIS. Good Luck!