Electron powder diffraction

Zuo, Jian‐Min; Lábár, János L.; Zhang, J.; Gorelik, Tatiana E.; Kolb, Ute

doi:10.1107/97809553602060000939

Cited by 5 publications

(4 citation statements)

References 91 publications

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“…In this evaluation approach, microscope lens distortions were parametrized as elliptical distortion, and higher-order distortions were neglected (note that the treatment of higher-order distortions is not implemented in currently available electron diffraction processing software). The FWHM values of the diffraction peaks were determined by fitting the pseudo-Voigt function [ 5 ] using Origin 2023b (10.05) software. Rietveld analysis was carried out using MAUD 2.99 software [ 21 , 22 ] with atomic scattering factors for electrons [ 23 ].…”

Section: Methodsmentioning

confidence: 99%

“…The Rietveld method is used less for the evaluation of electron diffraction patterns obtained from nanomaterials (SAED or EPD), mostly because of the potentially high contribution of multiple scattered electrons [ 5 ] and also because of the large influence of the setting of electron optics on the variation in detected intensity. The effect of multiple scattering on diffraction peak intensities as a function of the average atomic number and crystal thickness has been analyzed in the published literature in detail [ 5 ]. In nanocrystalline materials, in general, it is much weaker than single crystal samples [ 6 ].…”

Section: Introductionmentioning

confidence: 99%

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Improved Method for Electron Powder Diffraction-Based Rietveld Analysis of Nanomaterials

Kis,

Kovács,

Czigány

2024

Nanomaterials

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Multiphase nanomaterials are of increasing importance in material science. Providing reliable and statistically meaningful information on their average nanostructure is essential for synthesis control and applications. In this paper, we propose a novel procedure that simplifies and makes more effective the electron powder diffraction-based Rietveld analysis of nanomaterials. Our single step in-TEM method allows to obtain the instrumental broadening function of the TEM directly from a single measurement without the need for an additional X-ray diffraction measurement. Using a multilayer graphene calibration standard and applying properly controlled acquisition conditions on a spherical aberration-corrected microscope, we achieved the instrumental broadening of ±0.01 Å in terms of interplanar spacing. The shape of the diffraction peaks is modeled as a function of the scattering angle using the Caglioti relation, and the obtained parameters for instrumental broadening can be directly applied in the Rietveld analysis of electron diffraction data of the analyzed specimen. During peak shape analysis, the instrumental broadening parameters of the TEM are controlled separately from nanostructure-related peak broadening effects, which contribute to the higher reliability of nanostructure information extracted from electron diffraction patterns. The potential of the proposed procedure is demonstrated through the Rietveld analysis of hematite nanopowder and two-component Cu-Ni nanocrystalline thin film specimens.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Improved Method for Electron Powder Diffraction-Based Rietveld Analysis of Nanomaterials

Kis,

Kovács,

Czigány

2024

Nanomaterials

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“…It has been shown that even for nanoscale particles with isotropic ring patterns dynamic electron scattering cannot be fully ruled out, and quantification using Rietveld refinement requires dynamical corrections such as the two-beam approximation (Figure ). , Analysis software, such as MAUD, is freely available for this. Conversely, precession electron diffraction, where the electron beam is tilted and rotated in the form of a hollow cone, is an empirical way to mitigate the effect of dynamical scattering .…”

Section: Imaging and Spectroscopy In Operando Em Studiesmentioning

confidence: 99%

“…Furthermore, adequate compensation of elliptical distortions is essential, which can nowadays be achieved by effective machine learning algorithms . Those high-quality electron diffraction patterns can then also be used for pair distribution function (PDF) analysis. ,, This total scattering approach allows us to conclude on the nearest neighbors (local structures), domain, and particle sizes. This technique has been powerful enough to conclude on local structures in amorphous IrO x or AuAg NPs. , …”

Section: Imaging and Spectroscopy In Operando Em Studiesmentioning

confidence: 99%

Operando Electron Microscopy of Catalysts: The Missing Cornerstone in Heterogeneous Catalysis Research?

Chee,

Lunkenbein,

Schlögl

et al. 2023

Chem. Rev.

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Heterogeneous catalysis in thermal gas-phase and electrochemical liquid-phase chemical conversion plays an important role in our modern energy landscape. However, many of the structural features that drive efficient chemical energy conversion are still unknown. These features are, in general, highly distinct on the local scale and lack translational symmetry, and thus, they are difficult to capture without the required spatial and temporal resolution. Correlating these structures to their function will, conversely, allow us to disentangle irrelevant and relevant features, explore the entanglement of different local structures, and provide us with the necessary understanding to tailor novel catalyst systems with improved productivity. This critical review provides a summary of the still immature field of operando electron microscopy for thermal gas-phase and electrochemical liquid-phase reactions. It focuses on the complexity of investigating catalytic reactions and catalysts, progress in the field, and analysis. The forthcoming advances are discussed in view of correlative techniques, artificial intelligence in analysis, and novel reactor designs.

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Electron diffraction characterization of nanocrystalline materials using a Rietveld-based approach. Part I. Methodology

Sinha¹,

Bortolotti²,

Ischia³

et al. 2022

J Appl Crystallogr

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Transmission electron microscopy is a powerful experimental tool, very effective for the complete characterization of nanocrystalline materials by employing a combination of imaging, spectroscopy and diffraction techniques. Electron powder diffraction (EPD) pattern fingerprinting in association with chemical information from spectroscopy can be used to deduce the identity of the crystalline phases. Furthermore, EPD has similar potential to X-ray powder diffraction (XRPD) for extracting additional information regarding material specimens, such as microstructural features and defect structures. The aim of this paper is to extend a full-pattern fitting procedure, broadly used for analysing XRPD patterns, to EPD. The interest of this approach is twofold: in the first place, the relatively short times involved with data acquisition allow one to speed up the characterization procedures. This is a particularly interesting aspect in the case of metastable structures or kinetics studies. Moreover, the reduced sampling volumes involved with electron diffraction analyses can better reveal surface alteration layers in the analysed specimen which might be completely overlooked by conventional bulk techniques. The first step forward to have an effective application of the proposed methodology concerns establishing a reliable calibration protocol to take into correct account the instrumental effects and thus separate them from those determined by the structure, microstructure and texture of the analysed samples. In this paper, the methodology for determining the instrumental broadening of the diffraction lines is demonstrated through a full quantitative analysis based on the Rietveld refinement of the EPD. In this regard, a CeO2 nanopowder reference specimen has been used. The results provide indications also on the specific features that a good calibration standard should have.

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Electron powder diffraction

Cited by 5 publications

References 91 publications

Improved Method for Electron Powder Diffraction-Based Rietveld Analysis of Nanomaterials

Improved Method for Electron Powder Diffraction-Based Rietveld Analysis of Nanomaterials

Operando Electron Microscopy of Catalysts: The Missing Cornerstone in Heterogeneous Catalysis Research?

Electron diffraction characterization of nanocrystalline materials using a Rietveld-based approach. Part I. Methodology

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