Thermal variation of defect association in gadolinium doped ceria.

Gadolinium doped ceria (GDC) is currently being used as an oxide ion conducting electrolyte in intermediate temperature (ca. 500-700 deg C) solid oxide fuel cells (SOFCs). Our previous work on GDC samples isotopically enriched with 160Gd (which has a low absorption cross section) at room temperature has revealed evidence of dopant cation-oxide ion vacancy association as well as other local structural features. It is thought that the enthalpy of this association leads to an increased activation energy for conductivity at low temperatures but that at elevated temperatures the mobility of vacancies decreases this effect. Following, a recent study of neodymium doped ceria where this type of association was present but diminished at 600 deg C, we propose a more detailed study of the the thermal variation defect assocation in the technologically relevant system GDC.