Conductivity Fluctuations in Fast Ionic Conductors
Abstract
Electrical conductivity fluctuations in superionic solids provide a new way of examining transport and electrode properties of solid electrolytes. Of particular interest are the Na Beta and Na Beta double primed aluminas because of their high ionic conductivity, potentially important technological applications, and the ease with which the mobile sodium ions can be exchanged for a number of mono- and di-valent cations. Single crystal and ceramic specimens of sodium, silver, lead, and calcium Beta double primed aluminas, as well as mixed Na/Ag and Na/Ca conductors, have been found to exhibit conductivity fluctuations associated with diffusion of the mobile ions. Also, in the absence of electric current and at frequencies above about 100 Hz Nyquist noise corresponding to the bulk electrolyte resistance is observed. Below 100 Hz noise associated with amalgamation reactions at the electrolyte/contact interface or noise associated with ionic shot noise during the build-up of an electric double layer at the interface are dominant. Experimental diffusion noise levels can be quantitatively explained by focusing on the diffusion of ion-vacancy pairs in single conduction planes. Fluctuations in adjacent planes are correlated and corrections arising from in-plane coulomb forces are negligible.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1990
- Accession Number
- ADA227379
Entities
People
- James J. Brophy
Organizations
- University of Utah