Oxygen-vacancy-induced heterogeneous strain domains and dynamics on reducible oxide surfaces

Surface oxygen vacancies in ceria (CeO₂) appear as centers of extended strain fields reaching up to the nanoscale in the cation sublattice. Using transmission electron microscopy combined with density functional theory , the authors reveal highly heterogeneous (alternating tensile/compressive) and dynamic strain (high degree of fluxionality) landscapes, with both stable and unstable vacancies coexisting within a few atomic spacings. These findings characterize the structural footprint of surface defects and highlight the critical role of fluxional strain in governing cation functionality.