Journal
SOLID STATE IONICS
Volume 265, Issue -, Pages 22-28Publisher
ELSEVIER
DOI: 10.1016/j.ssi.2014.07.008
Keywords
Fluorite ceramics; Ceria; Equilibrium conductivity; Conductivity relaxation; Brouwer diagram
Categories
Funding
- Office of Naval Research [N00014-08-1-0539]
- Danish Ministry of Science, Technology and Innovation
Ask authors/readers for more resources
This is the first of a two-part paper that is concerned with measuring and interpreting equilibrium and transient conductivity for 10 at.% gadolinium-doped ceria (Ce0.9Gd0.1O1.95_delta 1 GDC10). AC impedance spectroscopy is used to measure conductivity of slender extruded GDC10 rods at temperatures between 700 and 900 degrees C. From the obtained Brouwer diagrams, the activation energies of the oxide ions and cerium small polarons are estimated to be 0.77 and 2.45 eV respectively. Conductivity relaxation measurements from strongly reducing conditions (4% H-2, 3% H2O, 93% Ar) to strongly oxidizing conditions (97% O-2,3% H2O) and vice versa reveal great asymmetries in relaxation times. Virtually instantaneous relaxations are observed in the first case, while the oxidizing-to-reducing relaxations take as long as 0.5 h. This paper reports conductivity relaxations with over 20 orders of magnitude in the gas-phase oxygen partial pressure. Models and experiments are used to show that the observed asymmetries cannot be explained by electrode defects or two-dimensional end effects. The companion paper develops a Nernst-Planck-Poisson model to assist the quantitative interpretation of the measurements reported in the present paper. (C) 2014 Elsevier B.V. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available