Influence of defect interactions on the electrical conductivity of gadolinium-doped ceria

Abstract

Gadolinium-doped ceria exhibits mixed ionic-electronic conduction at high temperatures and low partial pressures of oxygen (pO₂). In this study, the total electrical conductivity of Gd_0.10Ce_0.90O_2-δ (GCO) was investigated in the temperature range of 650–850 °C as a function of pO₂ between 10^-0.36 and 10^-25 bar. By concurrently modelling data of oxygen non-stoichiometry and electrical conductivity, our work reveals clear deviations from ideal solution behaviour. The observed decrease in the reduction enthalpy of GCO at low values of pO₂ can be accounted to net attractive defect interactions. These deviations from ideal solution behaviour can be traced back in the electrical conductivity data. A key distinction of the present study from previous ones is that it does not assume that the charge carriers in GCO are partially trapped in defect associates.