Applications of Impedance Spectroscopy

Real49 and Imaginary Impedance. One of the characteristics of electrochemical research papers on the application of impedance spectroscopy to find mechanisms is that they usually involve i (i = V—1), and the word imaginary. This needs some explanation. 

Careful attention has to be given to the purity of the precursors to avoid detrimental effects on conductivity. In a polycrystalline ceramic the conductivities of grain boundaries and bulk contribute to overall conductivity. In the case of polycrystalline YSZ, because of its unusually high intrinsic (bulk) conductivity the grain boundaries are far less conductive than the crystal, typically by a factor of 100. The effect the grain boundaries have on overall conductivity will depend on grain size and, of course, on impurity content (e.g. silica), since impurities tend to concentrate there. It is the effort to understand more of the various contributors to overall conductivity which has led to the application of impedance spectroscopy (see Section 2.7.5). 

Raistrick ID (1986) Application of impedance spectroscopy to materials science. Ann Rev Mater Sci 16 343-70... 

The profound variability in the skin s Impedance is one of the primary problems in the application of impedance spectroscopy to the study of the skin. It is thus necessary to control or remove as many factors as possible that lead to the variability in skin impedance before useful information can be obtained from impedance measurements [9]. Several methods have been proposed that can be implemented to decrease the variability of impedance measurements. Such methods include the following ... 

This book is intended to provide a background and training suitable for application of impedance spectroscopy to a broad range of applications, such as corrosion, biomedical devices, semiconductors and solid-state devices, sensors, batteries, fuel cells, electrochemical capacitors, dielectric measurements, coatings, elec-trochromic materials, analytical chemistry, and imaging. The emphasis is on generally applicable fundamentals rather than on detailed treatment of applications. The reader is referred to other sources for discussion of specific applications of impedance. ... 

Application of impedance spectroscopy is very much like feeling an elephant that we cannot see. Measurement of current and potential imder a steady state yields some information concerning a given system. By adding frequency dependence to the macroscopic measurements, impedance spectroscopy expands the information that can be extracted from the measurements. Impedance measurements, however, are not sufficient. Additional observations are needed to gain confidence in the model identification. 

Kendig, M. et al. "The application of impedance spectroscopy to the evaluation of corrosion protection by inhibitors and polymer coatings", CORROSION 85. 1985, NACE, Houston, Texas, Paper 74. 

Wang, M. Wang, L., Wang, G., Ji, X., Bai, Y., Li, T., Gong, S., and Li, J. (2004) Application of impedance spectroscopy for monitoring colloid Au-enhanced antibody immobilization and antibody-antigen reactions. Biosens. Bioelectron. 19, 575-582... 

As already mentioned, the formal transition to the frequency domain does not offer problems, yet in most cases the experimental application of impedance spectroscopy for evaluating the stoichiometric polarization is not of great worth as the frequencies used in the impedance experiments (as shown in Figure 44) are too high to observe the diffusion. Nonetheless, in such cases a combination of dc and ac methods is helpful, as the impedance branches which include bulk and boundary effects of Zr02 can be used to correct the steady-state value of the dc experiment (steady state initial value Onfy in cases of very... 

R. Juchniewicz, J. Janowski, Application of impedance spectroscopy to the assessment of cathodic protection effectiveness, in in J.M. Costa, A.D. Mercer (Eds.), Progress in Understanding and Prevention of Cathodic Protection Ineffectiveness, vol. II, EFC, London, 1993, pp. 1401-1410. 

When analyzing worldwide market of impedance spectroscopy instrumentation and comparing it to wide range of possible applications of impedance spectroscopy, it can be noticed that the nowadays portable impedance analyzer do not fulfill the current requirements neither functionally, nor costly nor dimensionally especially in case of test performed directly in the field including multi-point telemetric measurements. This leads to conclusion, that there is a need for miniaturized, low-cost and field-worthy impedance analyzers. Presented in the paper the impedance analyzers answer the existing needs. 

The applications of impedance spectroscopy are not limited to the characterization of electrode properties. Sometimes it is desirable to investigate the properties of membranes, solutions, or dielectrics. For this kind of appKcation, ur-eiectrode cells provide the best results. Two reference electrodes are placed in the electrochemical cell between counter and working electrodes (Fig. 23c). The impedance measured depends purely on the properties of the electrolyte or membrane between the two reference electrodes, and the electrode properties are completely eliminated from the impedance spectrum. 

Chemical applications of impedance spectroscopy began with the work of Nemst [5], followed by many others, including those applications to the distribution of relaxation time constants by Cole and Cole [6] and Davidson and Cole [7]. Warburg [8] developed the impedance of mass transfer (the so-called Warburg impedance), which allowed further applications of EIS to redox reactions. 

N. Bonanos, B.C.H. Steele, E.P. Butler, W.B. Johnson, W.L. Worrell, D.D. Macdonald, M.C.H. McKubre, Applications of impedance spectroscopy characterization of materials solid state devices corrosion of materials, in Impedance Spectroscopy Emphasizing Solid Materials and Systems, 1st edn., ed. by J.R. Macdonald (Wiley, New York, 1987)... 

The determination of dc ionic conductivity is perhaps the most widespread and also the simplest application of impedance spectroscopy. By using ac methods, electrode polarization can be correctly eliminated from an electrochemical system, and other sources of spurious frequency dispersion, such as grain boundary effects, may also be removed under certain circumstances. Electrodes may be inert foreign metals, thus eliminating the need for demonstrating the reversibility of parent metal electrodes. 

As applications of impedance spectroscopy to very complex reactions in the solid state have not yet been made, further development of the theory of the faradic... 

Chapter 4 Applications of Impedance Spectroscopy 4.7.2.2 Measurement Systems... 

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