Friday Lectures

by Evgenii Vlasov

Quantitative morphological analysis with SEEBIC in STEM: Applications and limitations

Practical

• location (online link) by invitation only
• Time: 11:30

Abstract

Recently we demonstrated that surface-sensitive secondary electron e-beam induced current (SEEBIC) in scanning transmission electron microscope (STEM) offers a promising alternative for the investigation of the morphology of nanomaterials and provide valuable information on the sample morphology with high spatial resolution and significantly shorter throughput times compared with electron tomography [1].

In this talk, I will discuss the practical aspects and applications of SEEBIC. We employed SEEBIC imaging for quantitative morphological analysis of wide range of nanomaterials. SEEBIC was used to quantify morphological chirality in gold nanoparticles with high throughput. We found that the average helicity values, calculated for hundreds of nanorods per sample batch, were in good agreement with the optical properties of the sample, confirming that helicity measurements enable linking the nanoscale morphology with the chiroptical handedness [2]. In addition, we have shown that SEEBIC images can be used for extraction of other morphological descriptors such as interwrinkle distance (groove width), length of the grooves and their coverage [3]. Next, SEEBIC proved useful for imaging food particles and nanoparticle self-assemblies, particularly in cases where overlapping features make conventional STEM analysis challenging.

However, it should be noted that SEEBIC images only provide a 3D perception of the object under investigation, whereas a real 3D structure remains hidden, which significantly limits quantitative interpretation of SEEBIC images in 2D. To retrieve the third dimension from SEEBIC image a forward model of the contrast  formation is required. In final part of my talk I will discuss the physics behind image formation and present analytical model for SEEBIC topography contrast.

In the outlook, I will outline potential application areas for SEEBIC that remain to be explored and suggest routes for improvement of a throughput and dose efficiency of the technique.

References:

1. E. Vlasov, A. Skorikov, A. Sánchez-Iglesias, L.M. Liz-Marzán, J. Verbeeck, and S. Bals, ACS Mater. Lett. 2023 5 (7), 1916-1921.
2. E. Vlasov, W. Heyvaert, B. Ni, K. Van Gordon, R. Girod, J. Verbeeck, L.M. Liz-Marzán, and S. Bals, ACS Nano 2024 18 (18), 12010-12019.
3. I.H. Ha, K. Van Gordon, R. Girod,  J.H. Han, E. Vlasov, S. Baúlde, J. Mosquera, K.T. Nam, S. Bals, and L.M. Liz-Marzán, submitted to ACS Nano.

by Maria Batuk

HAADF-STEM characterization of 2D TMD materials

Practical

• location (online link) by invitation only
• Time: 11:30

Abstract

In my lecture, I will introduce the “Hypersonic” Horizon Europe Pathfinder project, which focuses on 2D transition metal dichalcogenides (TMDs). The ultimate goal of the HYPERSONIC project is to advance the development of cost-effective printed electronic devices, specifically wearable pressure sensors. We have characterized various 2D TMDs produced through different methods, including CVD growth, microwave exfoliation, and electrochemical exfoliation, using atomic resolution high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM). These images have enabled us to directly visualize the defects present in the materials. In addition to qualitative analysis, we are conducting quantitative image analysis using StatSTEM. To gain novel insights into the materials, we plan to employ more advanced microscopy techniques such as integrated differential phase contrast (iDPC) and 4D STEM. However, we have encountered a significant challenge: organic residues on the materials are adversely affecting image quality, and this issue needs to be addressed.

by Hoelen Lalandec Robert 

Analytical ptychography: Low-dose imaging, event-driven detection and coherence

Practical

• location (online link) by invitation only
• Time: 11:30

Abstract

Advances in scanning transmission electron microscopy (STEM), such as event-driven detectors (EDD) [1], have contributed in making it a viable solution for the high-resolution imaging of beam-sensitive specimens such as 2D materials, zeolites or viruses. The recovery of a far-field diffraction pattern at each scan position enabled using computational imaging approaches such as analytical ptychography. Those approaches, which are both direct and computationally efficient, include the Wigner distribution deconvolution (WDD) and side-band integration (SBI) methods. As they permit the measurement of the projected electrostatic potential with a high signal-to-noise ratio [2,3], their continued development is of high importance across materials science and biology. 

This work aims at further exploring the capacity of analytical ptychography to measure the potential with low doses, i.e. below 103 e-/Å2 with atomic resolution, given realistic Poisson counting statistics an EDD [4]. This is done based on simulations, given a MoS2 monolayer and ice-embedded apoferritin. The dose-efficiency of both WDD and SBI, as well as of the integrated center of mass (iCoM) approach, are investigated and compared, for different numerical apertures and given a defocused illumination. General trends are thus evidenced, e.g. concerning the persistence of low- and high-frequency noise. The role of the contrast transfer function, and the assumption of weak scattering, are analyzed. Moreover, the scan-frequency partitioning algorithm (SFPA), a new memory-efficient and parallelizable solution to implement the methods, is demonstrated. 

With the fundamental analysis of dose-efficiency and contrast transfer having been done, a new framework for live and event-driven analytical ptychography, based on discretized electron incidences, is introduced. This framework, referred to as guided progressive reconstructive imaging (GPRI), consists in the in-line treatment of a detection stream, provided by an EDD, and in a cumulative reconstruction process. Its theoretical foundation, implementation and very low computational complexity, are discussed. Experimental and simulated application cases are demonstrated. 

Overarchingly, this work illustrates the high interest of analytical ptychography for the low-dose imaging of beam-sensitive objects. This is due to a direct and relatively simple formulation, which ensures reproducibility as well as short processing times. In that respect, those methods are particularly appropriate for a generalized application to routine measurements, with low cost-of-access for users. 

[1] D. Jannis et. al. ; Ultramicroscopy, 233, 113423 (2022) [2] C. O‘Leary et. al. ; App. Phys. Lett., 116, 124101 (2020) [3] C. O‘Leary et. al. ; Ultramicroscopy, 221, 113189 (2021) [4] H. L. Lalandec Robert et. al. ; submitted to Euro. Phys. Journ. App. Phys., arXiv:2501.08874v1

by Irina Skvortsova

​Investigation of unconventional metal halide perovskites and their self-assemblies​

Practical

• location (online link) by invitation only
• Time: 11:30

Abstract

Metal halide perovskites (MHPs) have emerged as highly promising materials for optoelectronic applications due to their exceptional optical properties, particularly highly efficient light emission with color tunability. Despite these advantages, the field has been predominantly focused on MHP nanocubes, which have long been considered the most thermodynamically stable morphology. However, recent advances in colloidal synthesis have begun to reveal a more diverse morphological landscape, introducing novel shapes such as armed structures, 26-faceted rhombicuboctahedron, and 12-faceted dodecahedra.

Beyond individual nanocrystals, the organization of CsPbBr₃ into ordered assemblies presents another compelling avenue of research. Superstructures of perovskite nanocrystals (NCs) have been shown to exhibit unique collective behaviors, such as superfluorescence and enhanced excitonic interactions, making them particularly attractive for quantum optics and advanced photonic applications. However, the majority of reported assemblies have been constructed from nanocubes, limiting the exploration of alternative architectures that could further tailor optical responses and energy transport phenomena.

Here, we investigated individual CsPbBr₃ armed structures, showing their experimental 3D shape for the first time. We elucidated the underlying reasons for their formation and suggested new synthetic approaches that enable precise control over arm length. By comparing the carrier dynamics of these structures with different arm lengths, we highlight the fundamental differences in exciton behavior arising from morphological variations. Furthermore, we proposed these armed structures as new alternative building blocks for perovskite assemblies, demonstrating their potential to maintain highly packed superstructures. Our findings offer fresh insights into the morphological diversity of CsPbBr₃ and open new pathways for engineering next-generation perovskite-based materials.

Beyond unconventional MHP shapes, we explored novel CsPbX₃/chalcohalide heterostructures, investigating a direct Cl⁻ → I⁻ halide exchange process that induces a striking shift in emission color from deep blue/UV to red. To gain insights into this process, we employed low-dose 4D scanning transmission electron microscopy (4D-STEM), which enabled us to resolve an intermediate CsPb(Cl,I)₃ mixed phase—a previously unobserved structure. Further quantification of X–Cs–X and Pb–Pb–X bond angles, along with lattice parameter analysis, allowed us to visualize the structural evolution between Cl-rich and I-rich domains at the atomic scale. Notably, for the first time, we demonstrated the segregation of I⁻ ions at the heterostructure interface between the MHP and chalcohalide. Furthermore, we observed the incorporation of I⁻ within the Pb₄S₃Cl₂ phase, evidencing Cl⁻/I⁻ substitution beyond the perovskite domain. These discoveries highlight the unique adaptability of these heterostructures, offering new design of tunable halide-exchanged materials with novel optoelectronic properties.

by Selma Mayda Bacaksiz

Theoretical investigation of oxygen vacancy induced structural transformation in TiO₂

Practical

• location (online link) by invitation only
• Time: 11:30

Abstract

We present a theoretical study on the effect of oxygen removal on the polyhedral framework in TiO₂. By using density functional theory calculations, we examine how oxygen vacancies change bond lengths and angles, resulting in modifications in both structure and electronic properties. Our results indicate that as oxygen vacancies increase, polyhedral distortions become more pronounced, which shows the changes in the system. Furthermore, our analysis suggests that beyond a critical vacancy concentration, local environments go significant rearrangements that strongly affect the electronic behavior. This work provides a theoretical foundation for understanding the relationship between oxygen vacancies, structural transformation, and electronic properties of  TiO₂.

by Luca Serafini

​Enhanced time resolution with a room-temperature energy dispersive X-ray PIN photodiode detector for improved EDX-EELS coincidence​

Practical

• location (online link) by invitation only
• Time: 11:30

Abstract

During EDX-EELS coincidence measurements, both spectroscopic signals are recorded simultaneously, and individual events are time-correlated. This enables the distinction between true electron-X-ray scattering events, which coincide in time, and unrelated background events, which do not. By filtering out uncorrelated signals, this approach significantly enhances the sensitivity of EELS to trace elements embedded in a matrix. For example, in nitrogen-vacancy centers in diamond, the nitrogen K-edge signal is typically weak and buried under background noise. Coincidence detection helps isolate these subtle edges, revealing otherwise undetectable elements with greater clarity.

However, coincidence measurements are currently limited by the low time resolution of commercial silicon drift detectors (SDDs), which constrain the signal-to-noise ratio. These column-mounted detectors evolved to large sizes to maximise collection efficiencies at the cost of time resolution due to long unpredictable drift times of the signal charge carriers created upon X-ray detection.

In order to improve this we are building a proof-of-concept detector for this application. Our approach consists of having a small fully-depleted Si-PIN photodiode detector mounted right next to the sample holder itself. Its small size ensures neglectable drift times, low capacitance and therefore high acquisition rates and high temporal resolution. Lastly having the sample close to the photodiode preserves collection efficiency.

by Amirhossein Hajizadeh

Capturing the Elusive SrFeO2.875 Phase: In-situ Observation of an Unseen Perovskite Formation

Practical

• location (online link) by invitation only
• Time: 11:30

Abstract

SrFeO3-δ and its doped phases are promising candidates for chemical looping. In this process, the perovskite structure reduces and oxidizes in a cycle at high temperatures. Therefore, the study of the phase transition of these materials to understand the mechanism of the process and the cause of their degradation would be essential.
Four different phases have been reported for SrFeO3-δ(2.5<δ<3). Nevertheless, several in-situ heating studies on this material with X-ray or Neutron diffraction methods did not observe the SrFeO2.75phase with the space group of Cmmm and SrFeO2.875 phase with the space group of I4/mmm.
In a previous research in our group, SrFeO2.75was revealed; however, no sign of SrFeO2.875 formation while heating in an oxidizing atmosphere was observed. So, we relaunched the experiment by considering altering new parameters in the search for the SrFeO2.875phase.
The results of our study show that this phase forms in a narrow temperature range while heating in the oxidizing atmosphere. Several other factors, such as preheating in a reducing atmosphere, affect its formation, and this phase can be observed partially or fully in all crystals by precisely controlling the temperature.

by Robin Girod

Investigating the morphology and structure of chiral gold nanoparticles with electron tomography

Practical

• location (online link) by invitation only
• Time: 11:30

Abstract

Chiral gold nanorods (NRs), which simultaneously exhibit circular dichroism and localized surface plasmon resonance, have promising applications in fields such as biosensing, therapeutics, and catalysis. However, understanding their complex shape-optical relationships and controlling their seed-mediated synthesis remain challenging. Since the morphologies of Au NRs can be complex, electron tomography (ET) has emerged as an important tool to visualize and quantitatively analyze the three-dimensional (3D) evolution of chiral gold nanoparticles during growth, aiming to better understand and optimize their production. I will first present an investigation of the micelle-templated chiral growth, in which we aimed to reconcile the growth behavior of fine helical surface wrinkles on single-crystalline or pentatwinned achiral seeds. Contrary to common assumptions, we found that the structure and geometry of the achiral seed influence the optical and geometrical handedness of the products. Moreover, a combination of conventional and atomic resolution ET showed that morphological evolution on different seeds occurs at different rates, but following common patterns. As a result, wrinkles follow a right-handed arrangement with 4-fold symmetry around single-crystalline nanorods, and a left-handed one with 5-fold symmetry around penta-twinned nanorods. Supported by molecular dynamics simulations, it is found that this growth behavior is consistent with templating micelles coiling not around the long axis of the rod as conventionally assumed, but along the <100> crystal directions. This insight has implications for achieving greater control over wrinkled nanorods growth.

Furthermore, understanding and optimizing the optical properties of Au NRs requires quantitative shape descriptors, which has posed significant challenges for chiral shapes. I will present a range of measures applicable to 3D ET reconstructions, including a helicity, and an asymmetry measure. Their predictive power and application towards the design and production of chiral nanoparticles with desirable properties will be discussed.

by Nadine Schrenker

Correlation of doping, microstructure, and morphology in perovskite systems

Practical

• location (online link) by invitation only
• Time: 11:30

Abstract

Metal halide perovskites (MHPs) are highly promising semiconductors for novel optoelectronic devices. Doping has been explored as a promising approach to control the electronic, magnetic, and optical performances of NCs. Lanthanide (e.g., Yb3+) doped MHP NCs show exceptionally high near-infrared photoluminescence quantum yields (PLQYs), and the lanthanide dopants promote phenomena of photomultiplication. Therefore, the objectives of my research stay at Monash University (Melbourne, Australia) were to understand the role of lanthanide doping in CsPbCl3 NCs and correlate the local microstructural insights with the optical properties. Via quantitative low-dose TEM experiments, it was observed that the CsPbCl3 NCs contain Ruddlesden-Popper (RP) phases, i.e., the structure is composed of n layers of CsPbCl3 unit cells that are separated by an additional CsCl layer. Moreover, the density of the RP defects decreases significantly for small NCs, which indicates that the RP defects compensate for strain in larger NCs.  The occurring RP defect configurations were also studied as a function of the added dopant (Mn2+ and Yb3+) and as a function of the initial synthesis conditions. The correlation of TEM investigations and optical measurements revealed that a slight Cs-excess in the precursor solution results in optimized optical properties despite a high density of RP defects.

In addition, prospectively combining perovskites and chirality will enable circularized polarized light emission or detection in novel optoelectronic devices. Two promising approaches to achieve chiral perovskites are through chiral cations or a chiral morphology of assembled nanocrystals. However, detailed mechanisms behind the chirality transfer, when chiral cations are used, are not yet fully understood and require more research at atomic scale. Therefore, the goal of this current project is to investigate the local structure of chiral perovskites via advanced 4D-STEM and tomography methods.

by Francisco Vega

Exploring Adaptive Optics in the Transmission Electron Microscope

Practical

• location (online link) by invitation only
• Time: 11:30

Abstract

Over the years, electron microscopes (EM) have evolved from basic imaging and magnification tools into versatile characterization instruments. They are now capable of reaching atomic resolution, reconstructing nanoparticles down to the atomic-position level, capturing dynamic processes in real time, resolving internal strains in crystal structures, and obtaining chemical compositions of various materials and alloys, among others.

All the applications mentioned above are largely enabled by the multidimensionality that can be achieved with the active elements within the EM column, i.e., the ability to control the electron wavefront as it propagates before and after its interaction with the sample. 

However, this multidimensionality is relatively limited compared to what can be achieved in other fields, such as light optics. There, the spatial light modulator (SLM) has revolutionized the field by introducing a position-dependent phase shift in the wavefront. In contrast, wavefront shaping in electron microscopy is significantly constrained by the spatial and physical limitations imposed on its active elements. 

Building on the capabilities provided by the multidimensional nature of the EM and motivated by the advancements in optics introduced by SLMs, the primary goal of this work is to develop a tool that enhances the multi-dimensional manipulation of wavefronts in electron optics. 

After designing and characterizing a spatial electron modulator (electrostatic phase plate), we will discuss the potential applications of this advanced wavefront shaping technology. Integrating this technology into the EM could enhance its capabilities and address current challenges in phase retrieval and the characterization of soft matter.

by Min Tang

Using in situ TEM to investigate the dynamic evolutions of Ni-TiO2 catalyst under oxidating and reducing conditions

Practical

• location (online link) by invitation only
• Time: 11:30

Abstract

Oxide-supported Ni catalysts are critical for a wide range of industrial manufacturing processes of fuels, chemicals and materials. It is now generally accepted that support materials are not inert and typically interact with Ni nanoparticles (NPs) through various routes, which significantly affects the properties of the solid catalysts. In particular, strong metal-support interaction (SMSI) refers to Ni NPs covered by overlayers from reducible oxide supports, such as TiO2, under high-temperature reduction. SMSI has been widely used to tune catalytic performances, including activity, selectivity, and stability for various chemical reactions. So far, most studies have investigated SMSI after pretreatment and linked the pre-formed SMSI states with catalytic performance. However, it is unclear how the SMSI formed after pretreatment will affect the structural evolutions of Ni-TiO2 with temperature or gas changes. By using in situ TEM, the dynamic changes of Ni-TiO2 were directly visualized at the atomic scale.”

by Matthias Quintelier

Practical

• location (online link) by invitation only
• Time: 11:30

Abstract

LDHs are layered materials with a wide range of applications, including electrocatalysis, fire retardants, chemical and electromagnetic absorption, ion exchange, biomedical uses, and environmental remediation. Their performance and properties are heavily influenced by their behavior at elevated temperatures, making in situ TEM heating experiments crucial for understanding these materials. By using HRTEM, HAADF-STEM, and µProbe 4DSTEM, I investigated the phase transformations of ZnAl LDH in both vacuum and air. While a porous structure formed in both conditions, the phase evolution was significantly affected by the environment. In vacuum, the material transitioned from LDH to spinel ZnAl2O4, then to ZnAl2O4 with Al2O3, and finally to a combination of Al2O3 and ZnO. In air, the transitions were from LDH to a mixture of LDH and ZnO, then to ZnO and ZnAl2O4, and finally to pure ZnAl2O4.

The second study focuses on PLE-4, a novel MOF synthesized using a cost-effective method to extend linkers. Despite its innovative synthesis, the resulting crystals exhibited poor crystallinity and low-resolution diffraction patterns, making it impossible to fully solve the structure using synchrotron XRD. However, 3DED experiments successfully resolved the structure despite similar resolution limitations. Standard structure solution methods like charge flipping and direct methods were unsuccessful, so we employed simulated annealing. In the second part of this talk, I will explain this technique, discuss the challenges encountered, and present the final structural solution. This study highlights the importance of looking beyond simple numerical indicators like R-factors to ensure accurate and meaningful structural interpretations.

by Nathalie Claes

Direct visualisation of ligands on gold nanoparticles in a liquid environment

Practical

• location (online link) by invitation only
• Time: 11:30

Abstract

The interaction between Au nanoparticles, their surface ligands and the solvent critically influences the properties of nanoparticles. Despite employing spectroscopic and scattering techniques to investigate their ensemble structure, a comprehensive understanding at the nanoscale remains elusive. Electron microscopy enables characterization of the local structure and composition but is limited by insufficient contrast, electron beam sensitivity and ultra-high vacuum, which prevent the investigation of dynamic aspects. In this talk it will be demonstrated that high-quality graphene liquid cells can overcome these existing limitations. This approach enables the investigation of the structure of the ligand shell around Au nanoparticles, as well as the ligand-Au interface in a liquid environment. Using this graphene liquid cell, the anisotropy, composition and dynamics of ligand distribution at the Au nanorod surface are visualized. Our results indicate a micellar model for the surfactant organisation. This work opens up a reliable and direct visualization of ligand distribution around colloidal nanoparticles.

by Héléna Verbeeck - Department of Materials Engineering, Faculty of Engineering KULeuven

Pyrometallurgical Recovery of Platinum Group Metals from Spent Automotive Catalysts: a Computational Approach

Practical

• location (online link) by invitation only
• Time: 11:30

Abstract

Recycling of Spent Automotive Catalysts (SACs) is crucial from both environmental and economic standpoints, as they are the primary source of valuable Platinum Group Metals (PGMs). PGMs, found in SACs as nanoparticles within a γ-Al2O3 layer on a cordierite substrate, are typically recycled through pyrometallurgical smelting. This process involves melting ground SACs with a flux, collector metal (CM), and reducing agent, forming a slag where CM droplets collect PGMs from the Al2O3 carrier. Encapsulation of PGMs by Al2O3 can impede their recovery, necessitating understanding Al2O3 dissolution in the slag and PGM collection in the CM during smelting. The phase-field method is the preferred numerical method for investigating diffusion and material interactions in this system. However, conventional phase-field models face limitations in simulating stoichiometric compounds, scaling to experimentally relevant length scales, and capturing interactions driven by large driving forces. We recently overcame challenges [1] by rederiving the phase-field equations to include composition independent Gibbs energy expressions for stoichiometric compounds in a multi-phase phase-field framework. Moreover, challenges related to spatial resolution and large driving-force interactions have been successfully overcome for diffusioncontrolled phase-field simulations. By integrating these advancements, we have developed a large-scale multi-phase multi-component phase-field model capable of simulating diffusion-controlled dissolution in systems with solution phases and stoichiometric compounds. This model facilitates the understanding dissolution of Al2O3 in CaO-Al2O3-SiO2 slags and PGMs partially encapsulated by Al2O3 in Cu CM droplets, crucial for pyrometallurgical recovery of PGMs from SACs, advancing computational methods in metallurgical engineering.  

References [1] Verbeeck, H., Feyen, V., Bellemans, I., & Moelans, N. (2024). Multi-phase-field modeling of the dissolution behavior of stoichiometric particles on experimentally relevant length scales. In Computational Materials Science (Vol. 245, p. 113288). Elsevier BV. https://doi.org/10.1016/j.commatsci.2024.113288.

by Valentina Girelli

Insight into the microstructure and porous network of zeolites

Practical

• location (online link) by invitation only
• Time: 11:30

Abstract

Porous materials represent an attractive class of materials due to their high specific surface and mass transport. Zeolites, a category of microporous crystalline aluminosilicates, combine these properties with an intrinsic acidic character, making them ‘first choice’ catalysts. However, hydrothermal instability and deactivation of catalytic sites can drastically reduce the efficiency of zeolites. Therefore, new strategies have been adopted in terms of material design, with the purpose of enhancing both the longevity and the activity in zeolites. The one presented in this study involves the extraction of Al from the lattice of zeolites Y of the Faujasite topology through thermochemical treatments, also termed dealumination. This process not only leads to a gain in thermal stability and acidity by tuning the Si/Al ratio, but it is responsible for the introduction of an auxiliary network of mesopores within the zeolite lattice, too. In such a context, this research aims to understand the role of each dealuminating treatment considering the morphological, structural and chemical modification in zeolites Y at the nanometric scale. These questions were tackled by using a series of stepwise treated samples, and by employing complementary (S)TEM-based techniques. DF-STEM tomography has allowed the quantification of the morphological descriptors of the mesoporous network at the different stages of the dealumination. In situ gas microscopy has tried to simulate the hydrothermal treatment inside the TEM environmental cell (Protochips systems), in the presence of water vapor, in order to reveal the structural rearrangement in the zeolite. EDX-STEM and EELS-STEM have led to a semi-quantitative mapping of the Si and Al indicating the heterogeneity of the treated samples. Finally, STXM-XAS characterization based on synchrotron light aimed to investigate the spectral signature of the Al on the K-edge during the dealumination and compare with reference aluminum oxide materials to understand which Al environments are dominant.​

by Saleh Gholam

4D-STEM Tomography as a Tool for Solving the Structure of Nanoparticles

Practical

• location (online link) by invitation only
• Time: 11:30

Abstract

Over the past decade, 3D Electron Diffraction (3D ED) has firmly established its position next to single-crystal X-ray diffraction (SC-XRD) and powder X-ray or neutron diffraction as a structure solution technique. Owing to the strong interaction of the accelerated electron beam with matter, there are no particle size limitations, in contrast to SC-XRD. Also, thanks to the high spatial resolution of transmission electron microscopes, impurities are not a serious problem, like in powder diffraction. However, in practice, an electron crystallographer can still face a lot of challenges.

“Conventional” 3D ED is still fundamentally a technique for single crystals and relies on parallel TEM illumination. Therefore, multi-phase or multi-grained particles, as well as any form of agglomeration, can complicate data collection and data processing. Furthermore, due to imperfections in the TEM stage, collecting tomography data becomes increasingly difficult as particle size decreases. In the case of tiny particles, assuming they have any contrast to be observed in TEM mode, maintaining illumination during tomography experiments as well as achieving a high signal-to-noise ratio are considerable challenges. These issues are further aggravated while dealing with beam-sensitive samples.

In this talk, I aim to demonstrate how 4D-STEM tomography, using fast pixelated detectors, can address these challenges by providing spatial resolution to the tomography experiments. To this end, we have automated data acquisition on our TEMs, as well as on a dedicated SEM for diffraction studies. We have analyzed multiple challenging samples, and propose several data analysis approaches. In the end, a graphical user interface is provided to facilitate the analysis of these heavy datasets for the users.

by Andrey Orkhov

Advantages and disadvantages of automation in electron microscopy: do we need an operator?

Practical

• location (online link) by invitation only
• Time: 11:30

Abstract

In the current era of artificial intelligence and automation, it is crucial to understand how these algorithms function and how we can apply them in our work. In my talk, I will try to critically examine the methods employed in electron microscopy and explore the potential benefits of automation. As examples, I will discuss several projects I have worked on where microscope automation facilitated the analysis of large fields of view, automated electron diffraction acquisition, stage manipulation, minimized beam damage, and ultimately saved time for other projects.

In the AutomatED project, we developed an automated electron diffractometer for high-throughput analysis of nanocrystalline powder samples. I will present recent advancements in technique development for obtaining electron diffraction data from non-electron transparent samples. The efficiency of the automated electron diffractometer was validated using relevant samples provided by the industry partners of the project. The results of this project demonstrate that the automated electron diffractometer can be a viable alternative to expensive transmission electron microscopes or X-ray diffractometers