What Nature Hides

The desirable properties of beta-silicon nitride (-Si3N4) ceramics in high temperature and pressure applications are hindered by its intrinsic brittleness. It has been empirically demonstrated, however, that sintering additives such as the rare-earth oxides can help to overcome this problem. Using a combination of atomic-resolution Z-contrast imaging and electron energy-loss spectroscopy (EELS) in the scanning transmission electron microscope, that permit probing local atomic structures and bonding characteristics with a resolution close to 1Å, I examine the atomic and electronic structures at the interface between Si3N4and CeO2-x inter-granular films (IGF). The image shows a typical Si3N4 sample, with the ceramic’s grains (in gray) surrounded by the CeO2-x IGF (in white). The inset is the high resolution image of the magnified portion of the Si3N4 grain. It reveals that Si3N4 is composed of hexagonal rings separated by 7.67Å from each other. The image was taken with the 2010keV electron microscope located at UIC and is provided unprocessed.