DOPANT-MODIFIED LOCAL CHEMICAL BONDING AT A GRAIN-BOUNDARY IN SRTIO3

The chemical bonding at a grain boundary of an Fe3+-doped SrTiO3 bicry stal has been determined by a combination of spatially resolved electr on energy-loss spectroscopy and a first-principles molecular-orbital c alculation. The near-edge structure of the O K-edge spectrum on the bo undary shows that the manner of the TiO6 linkage is different from tha t in the bulk SrTiO3. The linkage changes locally from a corner-sharin g to an edge-sharing configuration at the same time as the removal of Sr2+ ions from the boundary. This type of theoretical calculation is d emonstrated to be a powerful tool for analysing the ELNES spectra with out preconceived models.