Ac response of fractal interfaces

Conference · Thu Aug 01 04:00:00 EDT 1985

OSTI ID:5334384

Liu, S H; Kaplan, T; Gray, L J

The small signal ac impedance of the interface between a blocking electrode and an aqueous or solid electrolyte often contains a constant-phase-angle (CPA) element whose impedance has the frequency dependence according to Z proportional to (j..omega..)/sup -eta/. Recently it has been demonstrated experimentally that the exponent eta is intimately related to the roughness of the interface, with eta approaching 1 when the surface is made increasingly smooth. We propose to model the interface by a fractal called Cantor bar. The equivalent circuit of the model has the property of the CPA element with the exponent eta = 3 - ds, where 2 < ds < 3 is the fractal dimension of the interface. The model has been made more realistic by assuming random branching number and scaling ratio, and the relation between eta and ds remains the same. For real fractal surfaces the relation between eta and ds may hold approximately.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5334384
• Report Number(s): CONF-850870-1; ON: DE85017307
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400400* -- Electrochemistry
CHARGE TRANSPORT
ELECTRODES
ELECTROLYTES
EQUATIONS
IMPEDANCE
INTERFACES
ROUGHNESS
SURFACE PROPERTIES