Experimental limitations in impedance spectroscopy:: Part IV. Electrode contact effects

• Published in: Solid state ionics Vol. 98; no. 1; pp. 93 - 104
• Main Authors: Hwang, Jin-Ha, Kirkpatrick, K.S, Mason, T.O, Garboczi, E.J
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.06.1997; Elsevier Science
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conductivity phenomena in semiconductors and insulators; Contact impedance; Electronic transport in condensed matter; Exact sciences and technology; General theory, scattering mechanisms; General theory, scatteringmechanisms; Impedance spectroscopy; Physics; Point contact; Contact impedance; Point contact; Impedance spectroscopy; Temperature dependence; Pressure effects; Measuring methods; Computerized simulation; Solid-solid interfaces; Experimental study; Oxide ceramics; Spreading resistance; Contact surface; Partial pressure; Strains; Capacitance; Cerium oxides; Electric impedance; Electric conductivity; Equivalent circuits
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/S0167-2738(97)00075-1

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, oxygen partial pressure, and mechanical loading on the contact impedance of gold electrodes on nanophase cerium dioxide. Results were confirmed by pixel-based computer simulations.