The interaction of O vacancies and 180° domain walls in tetragonal PbTiO3 was investigated by using density-functional theory. The calculations indicated that the vacancies had a lower formation energy in the domain wall than in the bulk; thereby confirming the tendency of these defects to migrate to, and pin, domain walls. The pinning energies were reported for each of the 3 possible orientations of the original Ti-O-Ti bonds, and attempts to model the results with simple continuum models were considered.

First-Principles Study of Oxygen-Vacancy Pinning of Domain Walls in PbTiO3. L.He, D.Vanderbilt: Physical Review B, 2003, 68[13], 134103 (7pp)