EXELFS as a tool for quantifying phase distributions in materials

A method has been developed to quantify phase distributions in multiphase materials by using the information contained in the EXtended Energy Loss Fine Structure (EXELFS) of a probe atom in an Electron Energy Loss Spectroscopy (EELS) spectrum. The EELS and EXELFS determine, in addition 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 determined even in the presence of additional phases which do not share that common element. The method is particularly applicable to layered materials 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 relative thickness determination is about 5%. The near-edge fine structure information was consistent with the results of the EXELFS analysis.