Influence of the lattice constant on defects in cerium oxide

The lattice constant has a crucial effect on the defect chemistry and defect kinetics in solid state materials. However, within density functional theory, some functionals perform badly in reproducing the experimental lattice constant. In this study, energies of defect formation, interaction and migration in the model system ceria were calculated for different lattice constants to investigate the impact on the energies. The GGA+U functional in the PBE and PBEsol parametrization as well as the hybrid functional HSE06 were applied and results are compared among these three commonly applied functionals. The results suggest a strong influence of the lattice constant on the energies especially regarding oxygen ion migration. This influence has an impact on the accurate prediction of defect properties from first principles but can also be utilized for specific tailoring of material properties by chemo-mechanical design. In addition, the issue of the correct lattice constant, which should be used in the defect calculations, is discussed in this paper.