PROBING 3-D STRUCTURAL DISTORTIONS AND COORDINATION CHANGES AT SRTIO3GRAIN-BOUNDARIES USING ELECTRON-ENERGY-LOSS SPECTROSCOPY

Critical to a fundamental understanding of the structure-property rela tionships in ceramics is the ability to address the key issues of like -ion repulsion, partial occupancy, and composition at defect cores, He re, multiple scattering theory is used to produce a symmetry-projected , site-specific, density of states for defect structures observed expe rimentally in a SrTiO3 high-angle tilt grain boundary, The real space atomic clusters used in multiple scattering calculations do not rely h eavily on symmetry, thus permitting the structural origins of particul ar features to be readily identified in low-symmetry systems, Results are compared directly with experimental electron energy loss spectra a nd give strong evidence for partial occupied columns of atoms at speci fic interface cores and the persistence of bulklike atomic correlation s at the grain boundary.