In situ STEM Mechanical Experiments at Atomic-Resolution Using a MEMS Device

Abstract

In situ transmission electron microscopy (TEM) mechanical test is a powerful technique to directly observe microstructural evolution of crystalline materials upon loading. This technique can visualize the dynamic behavior of lattice defects, such as dislocation motion, twinning, or stress-induced phase transformation, at nanometer scale. These phenomena are essentially associated with atomic structure changes, and thus it is desirable to extend the technique to atomic scale. However, this is still challenge because of high demands laid on in situ TEM sample holders: (1) precise machinery for nanomechanical test, (2) double-tilt capability to align crystal orientation, (3) compatibility with narrow-gap pole pieces for atomic-resolution TEM. To satisfy these demands, miniaturized mechanical actuators are indispensable. Microelectromechanical systems (MEMS) technology is useful to fabricate electrical circuits, sensors, or mechanical actuators in micrometer order. MEMS devices have been applied to in situ TEM mechanical experiments [1], but there are few reports on in situ experiments under atomic-resolution observation. In this study, we developed a customized MEMS device for nanomechanical test compatible with a commercially available biasing TEM holder. Using this system, we demonstrate in situ mechanical test at atomic-resolution performed in an aberration-corrected scanning TEM (STEM).