EXELFS AS A TOOL FOR QUANTIFYING PHASE DISTRIBUTIONS IN MATERIALS

A method has been developed to quantify phase distributions in multiph ase materials by using the information contained in the EXtended Energ y Loss Fine Structure (EXELFS) of a probe atom in an Electron Energy L oss Spectroscopy (EELS) spectrum. The EELS and EXELFS determine, in ad dition to the atomic composition, the near-neighbor atomic environment about each atom type separately. The method is applicable to electron -transparent foils observed in a Transmission Electron Microscope (TEM ) equipped with a parallel-detection electron energy loss spectrometer . The relative amounts of phases that have a common element can be det ermined even in the presence of additional phases which do not share t hat common element. The method is particularly applicable to layered m aterials and can be used, for example, to determine the local relative thickness of a metal and its oxide layer. The Mg/MgO system was used to demonstrate the method, and it was found that the accuracy in relat ive thickness determination is about 5%. The near-edge fine structure information was consistent with the results of the EXELFS analysis.