Abstract
One of the most topical issues surrounding oxygen vacancies on is the relative stability of surface and subsurface defects. Using density-functional theory (DFT) with the HSE06 (Heyd-Scuseria-Ernzerhof) hybrid functional as well as the approach (where is a Hubbard-like term describing the on-site Coulomb interactions), we find subsurface vacancies with () periodicity to be energetically more favorable by 0.45 (HSE06), 0.47 [ (Perdew-Burke-Ernzerhof functional)], and 0.22 eV [ (local density approximation)]. The excess electrons localize not on Ce ions which are the nearest neighbor to the defect as priorly suggested, but instead on those that are next-nearest neighbors. The excess-electron distribution and the preference for subsurface vacancies are explained in terms of defect-induced lattice relaxation effects.
- Received 29 May 2008
DOI:https://doi.org/10.1103/PhysRevLett.102.026101
©2009 American Physical Society