Specifics of the data processing of precession electron diffraction tomography data and their implementation in the program PETS2.0

Abstract

Electron diffraction tomography (EDT) data are in many ways similar to X-ray diffraction data. However, they also present certain specifics. One of the most noteworthy is the specific rocking curve observed for EDT data collected using the precession electron diffraction method. This double-peaked curve (dubbed 'the camel') may be described with an approximation based on a circular integral of a pseudo-Voigt function and used for intensity extraction by profile fitting. Another specific aspect of electron diffraction data is the high likelihood of errors in the estimation of the crystal orientation, which may arise from the inaccuracies of the goniometer reading, crystal deformations or crystal movement during the data collection. A method for the refinement of crystal orientation for each frame individually is proposed based on the least-squares optimization of simulated diffraction patterns. This method provides typical angular accuracy of the frame orientations of less than 0.05 . These features were implemented in the computer program PETS 2.0. The implementation of the complete data processing workflow in the program PETS and the incorporation of the features specific for electron diffraction data is also described. electron crystallography 514 L. Palatinus et al. Structure refinement from PED Acta Cryst. (2019). B75, 512-522 electron crystallography Acta Cryst. (2019). B75, 512-522 L. Palatinus et al. Structure refinement from PED 517 electron crystallography Acta Cryst. (2019). B75, 512-522 L. Palatinus et al. Structure refinement from PED 521

Crossover from Germanite to Renierite-Type Structures in Cu22–xZnxFe8Ge4S32 Thermoelectric Sulfides

“…100 and 86 PED patterns were collected, respectively, on x = 0 and x = 2 Cu 22-x Zn x Fe 8 Ge 4 S 32 crystals with a precession angle of 1.2° and a tilt step about 1° between each pattern. PEDT data were processed using the programs PETS 2.0 29 and Jana2006. 30 The electrical resistivity (ρ) and Seebeck coefficient (S) were measured simultaneously from ingots, from 300 K up to 700 K using an ULVAC-ZEM3 instrument under partial helium pressure.…”

3D electron diffraction techniques

“…At the present there are several software programs that can handle ED data. Some of them are designed specifically for electrons such as ADT3D (Kolb et al, 2011), PETS (Palatinus et al, 2019), EDTProcess (Gemmi & Oleynikov, 2013) and RED (Wan et al, 2013), while others were developed for X-ray diffraction DIALS (Waterman et al, 2013;Clabbers et al, 2018), MOSFLM (Leslie & Powell, 2007) and XDS (Kabsch, 2010).…”

“…The patterns have been processed with the program PETS for indexing and intensity integration (Palatinus et al, 2019). We used as integration routine the integrated profile option which takes into account the angular distance in reciprocal space of reflection replicas that appear in consecutive patterns.…”

Structure solution and refinement of metal-ion battery cathode materials using electron diffraction tomography

“…Besides EDT, also PED on in-zone patterns has been used to solve and refine the LIB cathode materials structure (Hadermann et al, 2011). However, the increased completeness of reciprocal space coverage for EDT compared to inzone PED and the availability of user-friendly, free software such as PETS (Palatinus, 2011;Palatinus et al, 2019) has made EDT and PEDT the dominating methods for structure determination from electron diffraction at the time this review was written.…”