Representations of impedance spectra of ceramics: Part II. spectra of polycrystalline srtio3

Simultaneous representations of M″, Z″, A″, and tg(δ)) vs. frequency were used to analyze impedance spectroscopy data of SrTiO3 and to demonstrate the applicability of these representations. The log(tg(δ)) vs. log(f)) representation usually shows several local extremes (maxima or minima), which can be interpreted to obtain a wide range of relevant parameters, even for cases in which the Nyquist plot (Z″ vs. Z′) shows overlapped bulk and grain boundary arcs. Peaks of log(tg(δ)) indicate electrode to grain boundary transition, and/or the grain boundary to bulk transition. Local minima can be used to extract the grain boundary or the electrode relaxation frequencies. The admittance representation is slightly less useful. The modulus representation shows the bulk contribution term, but does not reveal the grain boundary or contributions of electrode terms.