Identification of local phase of nanoscale BaTiO₃ powders by high-resolution electron energy loss spectroscopy.

The electron energy loss spectroscopy (EELS) technique was applied to investigate the local variation in the phase of barium titanate (BaTiO₃) ceramics. It was found that the fine structure of the titanium L₂,₃ edge and their satellite peaks were sensitively varied with the tetragonal-cubic phase transition. The peak splitting of Ti-L₃ edge of tetragonal-phased BaTiO₃ ceramics was widened because of the increased crystal field effect compared with that of cubic-phased BaTiO₃. In case of nanoscale BaTiO₃ powders, the L₃ edge splitting of the core region was found to be smaller than that of the shell region. The energy gap between peaks t₂g and eg varied from 2.36 to 1.94 eV with changing the probe position from 1 to 20 nm from the surface. These results suggest that the EELS technique can be used to identify the local phase of sintered BaTiO₃ ceramics.