Cepstral Scanning Transmission Electron Microscopy Imaging of Disordered Crystals using Coherent Diffuse Scattering

Abstract

The development of four-dimensional (4D) scanning transmission electron microscopy (STEM) using fast detectors has opened-up new avenues for imaging defects, which ranges from being relatively simple, like virtual bright-or dark-field imaging, to being sophisticated, such as strain mapping using Bragg diffraction or Kikuchi/HOLZ lines. Here we introduce a new 4D-STEM technique, called Cepstral STEM, for imaging defects in crystals using electron diffuse scattering. In contrast to analysis based on Bragg diffraction, which measures the locally averaged d-spacings, elastic electron diffuse scattering can detect disruptions to the lattice. The disruptions, which gives rise to different types of diffuse scattering, include short range order, dislocations, stacking faults, and lattice distortion from crystal disorder. With the latter defines the atomic displacements from the average lattice sites, which differs from lattice strain that gives the change in local lattice parameters.