Gadolinium-Vacancy Clusters in the (111) Surface of Gadolinium-Doped Ceria: A Density Functional Theory Study

Solid-oxide fuel cells are promising devices for sustainable power generation. Electrolyte materials play an important role in connecting the anode and cathode, and they influence the performance of the device. In this context, gadolinium-doped ceria (GDC) has proven to be an efficient electrolyte material, although the presence of dopant clusters can lower its efficiency. After usage, dopant clusters start appearing at dislocations, translocations, grain boundaries, or surfaces. Hence, the study of dopant clustering at the atomic level near these regions becomes of vital importance, as it allows us to understand the reasons for the occurrence of this phenomenon and its impact on the oxygen conduction. In this context, the present paper studies the impact of dopant clustering near the (111) GDC surface. We have studied two different gadolinium concentrations in the material, of approximately 7% and 14%, which are close to the optimum concentration of 10%. Our results indicate that surface relaxation is a ...