Investigations of alumina/spinel and alumina/zirconia interfaces by spatially resolved electron energy loss spectroscopy

Two types of oxide hetero-interfaces, alumina/spinel and alumina/zirconia, have been investigated by spatially resolved electron energy loss spectroscopy (EELS) with nanometer-scale spatial resolution. Even using the sub-nanometer probe, changes in fine structures in valence and core loss regions across these interfaces are clearly observed and useful information can be successfully derived. We have detected the EELS signal delocalization when interpreting the evolution of the lower energy plasmon of zirconia near the interface and evidenced its energy dependence. the signal delocalization in insulators, such as ceramics, is rather important for the low loss region but practically negligible for the core loss region. Finally some of line-spectra analyses across the interfaces suggest the existence of strongly localized chemical states at the interfaces. These results demonstrate that spatially resolved EELS is a powerful and relevant tool for ceramics characterization at the subnanometer level. (C) 1998 Elsevier Science Limited. All rights reserved.