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

Gadolinium-doped ceria exhibits mixed ionic-electronic conduction at high temperatures and low partial pressures of oxygen ( p O 2 ). In this study, the total electrical conductivity of Gd 0.10 Ce 0.90 O 2-δ (GCO) was investigated in the temperature range of 650–850 °C as a function of p O 2 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 p O 2 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. • The total electrical conductivity of gadolinium-doped ceria is measured under various conditions • Modelling of oxygen non-stoichiometry and electrical conductivity data is performed • Observed decrease in the reduction enthalpy is attributed to net attractive defect interactions • The small electron polarons are not partly trapped in associate complexes with oxygen vacancies