Strain Mapping Using Precession Electron Diffraction Data

Elastic strain plays an important role in the mechanical properties and functionality of materials. Various transmission electron microscopy-based techniques have been developed to map elastic strain magnitude and distribution in samples. To our knowledge, most of the strain mapping techniques are limited to single crystals. In this work, we present a strain mapping method using shape memory alloys and VO2 thin film as model systems. This technique is based on cross-correlation to identify the center positions of the diffraction spot in the precession electron diffraction data. The histogram that summarises the distance between the direct beam spot and the diffracted beam spots can be plotted, which is analogous to the x-ray diffraction spectrum. Moreover, this technique enables the strain direction visualization of polycrystalline samples, especially those containing low-angle grain boundaries.