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 sp ectroscopy (SREELS) is demonstrated by investigating grain boundaries and planar faults in ceramics. This approach combines spatially-resolv ed energy-loss near-edge structure (ELNES), EELS quantification and as sociated spatial information on a subnanometer scale, and is based on an improved ''spatial difference'' method. This is a quantitative ''sp atial 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 E LNES for reference systems. Criteria to prevent artefacts are highligh ted. 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 obtaine d from quantification of the spectrum. Applying this approach to lines cans (''Spectrum-Line'') not only achieves very high spatial resolutio n, but also provides an effective probe size. A spectrum for a planar fault of 0.22 nm width was obtained.