A QUANTITATIVE APPROACH FOR SPATIALLY-RESOLVED ELECTRON-ENERGY-LOSS SPECTROSCOPY OF GRAIN-BOUNDARIES AND PLANAR DEFECTS ON A SUBNANOMETER SCALE

A quantitative approach for spatially-resolved electron energy-loss spectroscopy (SREELS) is demonstrated by investigating grain boundaries and planar faults in ceramics. This approach combines spatially-resolved energy-loss near-edge structure (ELNES), EELS quantification and associated spatial information on a subnanometer scale, and is based on an improved ''spatial difference'' method. This is a quantitative ''spatial difference'' which analyses elements present at defects as well as in the bulk, and which is performed with a systematic procedure to subtract completely the signal of the bulk based on the knowledge of ELNES for reference systems. Criteria to prevent artefacts are highlighted. The processed spectrum is dedicated to a defect, and may include signals from more than one element. Spatial information associated to the defect, such as the chemical width of a grain boundary, is obtained from quantification of the spectrum. Applying this approach to linescans (''Spectrum-Line'') not only achieves very high spatial resolution, but also provides an effective probe size. A spectrum for a planar fault of 0.22 nm width was obtained.