Inductive Loops in Impedance Spectra of Polarized SrTiO3 Thin Films: A Trace of Oxide Ion Motion Rather than an Experimental Artefact

Tuesday, 4 October 2016 CONVENTION CENTER: Exhibit Hall 2 (Hawai'i Convention Center) J. Fleig, S. Taibl, and G. Fafilek (TU Wien) Several reasons may cause inductive loops in impedance spectra of solid state electrochemical systems. Some of them are simply artefacts due to instrumental effects [1] or due to an unfavorable sample set up [2]. In this contribution, we discuss inductive loops which represent true sample properties of oxide thin films. A detailed analysis of the loops even introduces a novel method for measuring the ionic conductivity of oxides with very low ionic transference number. Slightly Fedoped SrTiO3 (Fe:STO) thin films on a conducting Nb-doped SrTiO3 substrate were investigated by means of impedance spectroscopy under DC voltages in the +/500 mV range. For all temperatures (ca. 300°C 700°C) the applied bias voltage causes either an unusual “inductive loop” in the low frequency range of impedance spectra (see Fig. 1) or an additional semicircle. Moreover, current-voltage (I-V) curves strongly vary with changing scan rate and the shape of quickly measured I-V curves depends on the starting voltage.