Atomic scale characterization of oxygen vacancy segregation at SrTiO3 grain boundaries

We have examined the atomic structure, composition, and bonding at a nominally undoped 58° [001] tilt grain boundary in SrTiO3 in order to develop an understanding of the control that the grain boundary plane exerts over the bulk properties. Room temperature and in situ heating experiments show that there is a segregation of oxygen vacancies to the grain boundary that is increased at elevated temperatures and is independent of the cation arrangement. These measurements provide direct support for recent experimental and theoretical predictions that nonstoichiometry, and in particular oxygen vacancies, are responsible for the widely observed grain boundary properties.