Effect of SiO2 on charge transfer at the Zirconia/Electrode interface

Synchrotron radiation spectroscopy was applied to examine the compn. and structure of an electrode/ZrO2 electrolyte interface belonging to a solid-state electrochem. cell used to study the oxidn. kinetics of Ni at high temps.  After the expt., XANES (x-ray absorption near edge structure) spectra detected a SiO2-like thick layer interposed between the oxidized Ni surface and the Y2O3-stabilized ZrO2 electrolyte.  The presence of the glassy layer is used to explain, in terms of the resistance overvoltage under galvanostatic conditions, the anomalous behavior previously found in the Arrhenius plot of NiO cond.  An energy gap of 6 eV was found for the electronic cond. of the glassy layer.  Hypotheses on its chem. compn. were made on the basis of the impurity data of the solid electrolyte and the related phase diagrams with SiO2.