EXPERIMENTAL LIMITATIONS IN IMPEDANCE SPECTROSCOPY .3. EFFECT OF REFERENCE ELECTRODE GEOMETRY POSITION/

Experiments and computer simulations on Pt/YSZ specimens in various el ectrode configurations were performed to investigate the effect of ref erence electrode geometry/position on the accuracy of impedance measur ements. The internal, Luggin probe-type, geometry is the preferred ref erence electrode configuration as it accurately measures both electrol yte and electrode impedances. External, 'pseudoreference', electrodes sample an averaged effective potential and can register inaccurate ele ctrolyte resistances, sometimes with distorted electrode arcs. A symme tric configuration can accurately measure the impedance of an electrod e; however, the electrolyte resistance will not scale linearly accordi ng to sample dimensions, as one might expect, An asymmetric configurat ion exhibits both non-linear partitioning of electrolyte resistance an d distortions in the electrode impedance are under certain circumstanc es. The reliability of three-electrode measurements is very sensitive to aspect ratio and electrode configuration.