In situ transmission electron microscopy (TEM) has become anincreasingly important tool for materials characterization. It provides keyinformation on the structural dynamics of a material during transformations andthe ability to correlate a material’s structure and properties. Withthe recent advances in instrumentation, including aberration-corrected optics,sample environment control, the sample stage, and fast and sensitive dataacquisition, in situ TEM characterization has become morepowerful. In this article, a brief review of the current status and futureopportunities of in situ TEM is provided. The article alsointroduces the six articles in this issue of MRS Bulletinexploring the frontiers of in situ electron microscopy,including liquid and gas environmental TEM, dynamic four-dimensional TEM,studies on nanomechanics and ferroelectric domain switching, andstate-of-the-art atomic imaging of light elements (i.e., carbon atoms) andindividual defects.
