Impedance Spectroscopy: True and Observable Asymptotic Models

Sioma Baltianski

Abstract

The decomposition process of the entire impedance spectra into its separate parts is accomplished by data fitting using a parametric distribution function of time constants in a convoluted form. Each particular part of the impedance spectrum is represented as an asymptotic model in the next step. Our technique lies within the branch of direct approaches showed in a concept map that describes analysis options of Impedance Spectroscopy. The direct fitting of the impedance spectrum by a detailed equivalent circuit is challenging due to its ambiguity. A comparative analysis of the asymptotic models is performed using different fitting functions. It is shown here that only Gauss impedance can obtain a "True" asymptotic model. All other known distribution functions used for impedance fitting result in only "Observable" asymptotic model. Correct interpretation relies on obtaining accurate data over wide ranges of frequencies, impedances and temperatures. The results were obtained using a custom-made impedance measurement system based on Precision Impedance Analyser and a Lock in Amplifier. The samples were dense ceramics tested in the temperature range of 200-475 ºC and the frequency range of 10^-2-3×107 Hz.

Keywords

impedance spectroscopy, asymptotic model, Gauss impedance

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IMEKO TC

TC4 - Measurement of Electrical Quantities

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