Self-Diffusion in Perovskite and Perovskite Related Oxides: Insights from Modelling

Perovskite and perovskite related oxides are important materials with applications ranging from solid oxide fuel cells, electronics, batteries and high temperature superconductors. The investigation of physical properties at the atomic scale such as self-diffusion is important to further improve and/or miniaturize electronic or energy related devices. In the present review we examine the oxygen self-diffusion and defect processes in perovskite and perovskite related oxides. This contribution is not meant to be an exhaustive review of the literature but rather aims to highlight the important mechanisms and ways to tune self-diffusion in this important class of energy materials.

A computational modelling study of oxygen vacancies at LaCoO3 perovskite surfaces

Atomistic computational modelling of the surface structure of the catalytically-active perovskite LaCoO(3) has been undertaken in order to develop better models of the processes involved during catalytic oxidation processes. In particular, the energetics of creating oxygen ion vacancies at the surface have been investigated for the three low index faces (100), (110) and (111). Two mechanisms for vacancy creation have been considered involving dopant Sr(2+) cations at the La(3+) site and reduction of Co(3+) to Co(2+). For both mechanisms, there is a general tendency that the smaller the cation defect separation, the lower the energy of the cluster, as would be expected from simple electrostatic considerations. In addition, there are clear indications that oxygen vacancies are more easily created at the surface than in the bulk. The results also confirm that the presence of defects strongly influences crystal morphology and surface chemistry. The importance of individual crystal surfaces in catalysis is discussed in terms of the energetics for the creation of oxygen vacancies.