Investigation of Cathode Behavior and Surface Chemistry of Model Thin Film SrTi1-xFexO3-δ Electrode

Abstract

The defect and transport properties of dense thin films of SrTi1-xFexO3-δ (STF), deposited by PLD onto single crystal YSZ and MgO substrates, were investigated based on the analysis of the chemical capacitance and the DC electrical conductivity as a function of temperature, pO2, and Fe fraction. The magnitude of the surface exchange coefficient, k, was found to be only weakly dependent on the magnitudes of the electronic and ionic conductivities as well as carrier densities (over nearly five orders of magnitude change in σel) over the x values (0.01-1.0) examined in this study. On the other hand, an appreciable degree of Sr-excess near the surface of the STF thin film was found by means of XPS over the whole Fe fraction from x=0.05-1.0. The observed defect, transport, and surface chemical properties are discussed in relation to the cathodic behavior of the STF thin film electrodes.