Fingerprinting the α and γ phases of alumina using electron energy - loss spectroscopy

The alpha and gamma phases of aluminum oxide were fingerprinted using electron energy-loss spectroscopy (EELS) with an energy resolution of 0.4 eV. Electron diffraction and powder x-ray diffraction were used to determine the phase of micron and nanopowder alumina samples. The results from indexing peak and ring diffraction patterns proved to be ambiguous and were resolved by comparing EELS spectra with published fingerprints. EELS spectra were generated from the powders with an energy resolution of 0.4 eV. This energy resolution was achieved using a Tecnai F20 Analytical Scanning Transmission Electron Microscope (STEM) equipped with a monochromator, Gatan energy filter (GIF) and high resolution spectrometer in STEM mode. These fingerprints are compared with published data and discrepancies between the spectra are discussed. The significance of using a monochromator with STEM mode for nanoparticle phase identification is addressed, followed by a brief roadmap delineating the goals of future EELS phase identification research. Table of