Abstract: The AC impedance technique is one of the important methods for electrochemical study. We have discovered that there is a certain transformation relationship between the equivalent circuits for similar plots on an impedance complex plane and on a capacitance complex plane. The transfer rule for an equivalent circuit being composed of the resistance and the capacitance has been given in our previous papers. Herein we give the transfer rule for an equivalent circuit including Warburg impedance as follows: for the equivalent circuit involving Warburg impedance, if we make the following transformation, (1) a resistance is substituted for a capacitance, and a capacitance for a resistance, (2) a Warburg impedance is changed to a Warburg transform, and a Warburg transform is changed to a Warburg impedance(the Warburg transform is expressed by a parallel connection of a resistance and a capacitance subjecting to the prerequisite of ωRC=1, R=Wω^-1/2 and 1/(ωC)=Wω^-1/2, here constant Wis the proportional factor), and (3) a parallel connection is changed to a series connection, and a series connection to a parallel connection, then the plot on the ZdZc plane for the original equivalent circuit and the plot on the CdCc plane for the transferred one, or the plot on the CdCc plane for the original equivalent circuit and the plot on the ZdZc plane for the transferred one are similar, respectively. This means that impedance of the original equivalent circuit has the similar expression with capacitance of corresponding transferred one. Using the transfer rule the study results on a plot on one complex plane can be directly used to a similar plot on another complex plane. Therefore, the transfer rule is a useful tool for the ACimpedance study.

Key words: Electrochemistry, AC impedance, Equivalent circuit, Warburg impedance, Ggraph transformation