DIRECT DETERMINATION OF GRAIN-BOUNDARY ATOMIC-STRUCTURE IN SRTIO3

An atomic structure model for a 25 degrees [001] symmetric tilt grain boundary in SrTiO3 has been determined directly from experimental data with the use of high-resolution Z-contrast imaging coupled with elect ron energy loss spectroscopy. The derived model of the grain boundary was refined by bond-valence sum calculations and reveals candidate sit es for dopant atoms in the boundary plane. These results show how the combined techniques can be used to deduce the atomic structure of defe cts and interfaces without recourse to preconceived structural models or image simulations.