Imaging of the crystal structure of silicon nitride at 0.8 Ångström resolution1Work supported by the Director, Office of Science, Office of Basic Energy Sciences, Materials Sciences Division of the US Department of Energy under Contract No. DE-AC03-76SF00098.1

High-resolution transmission electron microscopy is utilized to examine the crystal structure of a silicon nitride ceramic using focus variation methods to achieve sub-ångström resolution at the absolute theoretical information limit of the transmission electron microscope. Specifically, crucial requirements of high instrumental stability, a coherent electron source and optimum imaging conditions have been met by the one-Ångstrom microscope (OÅM) at the National Center for Electron Microscopy in order to obtain a resolution of 0.8 Å. The resulting high-resolution images reveal the individual atom positions of the in-plane projected crystal structure of silicon nitride and permit detailed structural information. The images correspond closely to computed and simulated images of this crystal structure.