An O vacancy in a Σ = 3(111)[10¯1] grain boundary in SrTiO3 was modelled by using density-functional theory plane-wave pseudopotential methods. The formation energy of the vacancy in the boundary was found to depend upon its charge state and on the electron chemical potential. There was a strong driving force for segregation when the vacancy was in the charge neutral state and this results in an electrostatic potential barrier at the GB. The vacancy was found to act as a donor and the GB became n-type. The defect induces small atomic relaxations in an otherwise highly ordered GB structure.

First-Principles Calculations of an Oxygen Deficient Σ = 3 (111)[10¯1] Grain Boundary in Strontium Titanate. R.Astala, P.D.Bristowe: Journal of Physics - Condensed Matter, 2002, 14[25], 6455-67