Molecular dynamics simulation on ionic conduction process of oxygen in Ce1−xMxO2−x/2

Molecular dynamics simulation of CeO2 doped with M3+ (a trivalent cation) with ionic radii ranging from 1.019 Å (Y3+) to 1.160 Å (La3+) were performed to examine the effects of the dopant cation size on ionic conductivity. Interatomic potential parameters were empirically fitted with equilibrium properties and energy barriers from ab initio calculations. Vacancy trapping and edge blocking mechanisms were studied. Analysis on vacancy trapping showed that the effect was more pronounced in La- and Y-doped ceria than those doped with Gd and Sm. Analysis of the edge blocking effect showed that larger-sized dopants would limit the available pathways for vacancy hopping. The combined effects satisfactorily explained the influence of the dopant cation size on the ionic conductivity of heavily doped ceria.

► We model doped ceria using molecular dynamics with a new of interatomic potential. ► We study doped ceria at various compositions and temperatures and investigate atomistic mechanism of ionic conduction. ► Vacancy trapping is more pronounced in La- and Y- doped ceria than Gd- and Sm-. ► Combined vacancy trapping and edge-blocking effects explain the influence of the dopant cation size on the ionic conductivity of doped ceria.