Experimental Limitations in Impedance Spectroscopy. Part 4. Electrode Contact Effects.
Experimental Limitations in Impedance Spectroscopy.
Part 4. Electrode Contact Effects.
Hwang, J. H.; Kirkpatrick, K. S.; Mason, T. O.;
Garboczi, E. J.
Solid State Ionics, Vol. 98, 93-104, 1997.
cerium dioxide; impedance; simulation; spreading
A 'spreading resistance' contact between electrode and
specimen can increase or even dominate the apparent bulk
resistance of an electroceramic specimen. For true
point contacts, a single arc will appear in impedance
spectra, whose diameter is essentially the spreading
resistance due to the contact and whose time constant is
identical to that of the bulk, but with a
correspondingly smaller capacitance. When a planar
electrode with multiple point contacts is involved, a
separate electrode arc occurs whose diameter is due to
spreading resistance, but whose capacitance tends to be
dominated by the 'air gap' capacitance between the
electrode and the rough surface of the ceramic. In this
study impedance spectroscopy was employed to study the
effects of temperature, oxgyen partial pressure, and
mechanical loading on the contact impedance of gold
electrodes on nanophase cerium dioxide. Results were
confirmed by pixel-based computer simulations.