ElectronDiffraction tools, a DigitalMicrograph package for electron diffraction analysis

Abstract

Microstructure analysis based on the electron diffraction patterns (ED or SAED) or high-resolution transmission electron microscopy images (HRTEM) has become a major technique for the local structural characterization of materials. Three traditional methods of electron diffraction analysis are pattern indexing, phase identification, and unit cell determination. But for the lack of analysis tools, most of the people usually manually measure the diffraction spots to index the diffraction pattern or measure a few lattice planes (fringes in HRTEM or diffraction rings) to perform phase analysis. For the need of the daily-used diffraction analysis, we present a new processing & analysis package for electron diffraction pattern, ElectronDiffraction tools. The program was written as a package of DigitalMicrograph, a very popular software to record and analyze the data of transmission electron microscopes (TEM). Autocorrelation and digital filter method were implanted in it to yield a high-quality Fourier transform diffractogram from an HRTEM image, Gaussian filter and Gaussian fitting were applied to locate diffraction spots with sub-pixel accuracy. It can automatically measure diffraction spots to index the spotty-like diffraction pattern of the known crystal; intensity profile or surface plot extracted from a diffraction pattern can be used to carry out phase analysis just like ‘Search-Match’ in XRD, and the extracted d-spacing table can be used to determine the unit cell of the unknown crystal. Program summaryProgram Title: ElectronDiffraction toolsProgram Files doi:http://dx.doi.org/10.17632/mfw96cbgp4.1Licensing provisions: GNU Public License GPLv3Programming language: DigitalMicrograph scripting languageNature of problem: It is a time-consuming procedure with a large analysis error for the traditional TEM analysis based on the SAED pattern or HRTEM images.Solution method: Gaussian filtering and Gaussian fitting are implemented in ElectronDiffraction tools to automatically measure diffraction spots for the pattern indexing and the extraction of the d-spacing table. The azimuthal rotation-average projection is applied to extract the intensity profile, linear image and its surface plot for the phase analysis. Moreover, an accurate d-spacing table derived from spots extension can be used to determine the unit cell of the unknown crystal.Additional comments: The program can also be obtained from https://github.com/hlshi527214/ElectronDiffraction-tools/tree/master/Installer%20files