The Temperature and Compositional Dependence of the Electrical Conductivity of Nonstoichiometric CeO[sub 2−x]

Abstract

The electrical conductivity of sintered specimens of nonstoichiometric Formula was measured as a function of temperature from 1000°−300°C and composition from Formula . These results are described in terms of a high temperature and low temperature region. In both temperature regions the conductivity for fixed values of x exhibits an exponential dependence on temperature, Formula . The temperature of the intersection between the high and low temperature regions for each composition agrees closely with the composition‐temperature dependence of the miscibility gap reported by Brauer and Gingerich. The compositional and temperature dependence of the conductivity in the high temperature region, which corresponds to a single‐phase region, may be represented by the expression Formula where Formula is a function of Formula . This expression is rationalized in terms of simple relations for the electron carrier concentration, Formula , and the electron mobility, Formula , where Formula is independent of Formula . For Formula between −3.0 and −1.8, Formula is constant at 0.22 eV, but increases to Formula . In the low temperature region the activation energy, 0.61 ± 0.03 eV, was found to be independent of Formula .