Electrolyte changes caused by point contact electrodes on Sr(Zr,Dy)O3−δ

Pt point contact electrodes were used to characterise the cathodic processes occurring at the Sr(Zr,Dy)O3−δ/Pt contacts. The cathodic polarisation experiments were performed in a potentiostatic mode by superimposing an AC signal on a DC bias. Impedance spectra in the frequency range 10−3–105 Hz were thus used to separate the ohmic resistance from the electrode contribution in atmospheres containing H2 and H2O. The ohmic losses decrease with increasing applied DC bias, and post-mortem EDS analysis revealed Sr-segregation at the point contact electrode, probably because the electric field is sufficiently high near the point contact electrode even for moderate applied voltages. The ohmic resistance also increases slowly after a sudden interruption of the DC bias, suggesting a diffusion controlled recovery.