Electrolyte changes caused by point contact electrodes on Sr(Zr,Dy)O3-delta

Pt point contact electrodes were used to characterise the cathodic processe s occurring at the Sr(Zr,Dy)O3-delta/Pt contacts. The cathodic polarisation experiments were per-formed in a potentiostatic mode by superimposing an A C signal on a DC bias. Impedance spectra in the frequency range 10(-3)-10(5 ) Hz were thus used to separate the ohmic resistance from the electrode con tribution in atmospheres containing H-2 and H2O. The ohmic losses decrease with increasing applied DC bias, and post-mortem EDS analysis revealed Sr-s egregation at the point contact electrode, probably because the electric fi eld is sufficiently high near the point contact electrode even for moderate applied voltages. The ohmic resistance also increases slowly after a sudde n interruption of the DC bias, suggesting a diffusion controlled recovery. (C) 2000 Elsevier Science B.V. All rights reserved.