A computational study of gadolinium-doped ceria: Relationship between atomic arrangement and electrostriction

Experimental studies have found a giant electrostriction effect in gadolinium-doped ceria (GDC) despite its low permittivity. This unique phenomenon has been linked to the presence of overcompensating vacancies and to the occurrence of a phase transition, implying an abrupt change in cation-oxygen bond distance. In this study, we have used computational methods based on density functional theory and on interatomic potentials to help understand the mechanism of the electrostriction effect in GDC. By combining these two methods, we obtained the lowest-energy configurations of Ce_1−xGd_xO_2−x/2 in the entire range of x. Our results suggest that no ordinary phase transition exists as a function of the composition. However, the atomic rearrangements that occur as the concentration of vacancies and dopants increases cause an abrupt change in cation-oxygen bond distance that could be responsible for the electrostrictive properties of GDC.