In Situ 4D-STEM—The Best of Both Worlds

In situ transmission electron microscopy (TEM) experiments are typically recorded either in real space or diffraction space. However, it would be ideal to have both real and diffraction space for when transient events occur that cannot be repeated exactly (ie- defect generation or irreversible phase transformations). Real space imaging provides context for these transient events by spatially-resolving microstructural features to one another while diffraction space provides better structural clarity about phase identification and lattice parameters. Four-dimensional scanning transmission electron microscopy (4D-STEM), can come close to providing both simultaneous real-space imaging and diffraction analysis during in situ testing. This talk will show examples of in situ 4D-STEM experiments from the early days of 4D-STEM to the current day. These examples will include observations of plastic deformation, phase transformations and intercalation in 2D materials.