Sandra Van Aert full research professor

Research Sandra Van Aert

Research team

Expertise

Sandra Van Aert's research focuses on new developments in the field of model-based electron microscopy aiming at quantitative measurements of atomic positions, atomic types, and chemical concentrations with the highest possible precision. These techniques are applied to advanced materials.

Tracking Nanomaterial Performance, Towards Digital Twins of Quantum Dots Under Loading (TRACK THE TWIN). 01/12/2024 - 30/11/2028

Abstract

Quantum dots (QDs) exemplify the successful transfer of innovative nanomaterials from a lab-scale invention to a technology that offers better and more power-efficient electronic devices, or makes buildings generate renewable energy. Such implementations, however, keep QDs under permanent loading, such as constant illumination, elevated temperature or exposure to environmental agents. Efforts to make QDs resilient against loading-induced ageing and loss of performance are time-consuming and costly. Track The Twin addresses this problem through a research and training program aimed at creating and using QD digital twins (QDDTs). Focused on the case of QDs under illumination, this goal creates an exceptionally rich environment to form a new cohort of early-stage researchers (ESRs) in nanomaterials. Trained as experts in the latest methods of synthesis, structure analysis and time-resolved spectroscopy – from infrared to x-ray - and computational materials science, ESRs will learn to join forces to reach the common goal of demonstrating loading-resilient QDs synthesized according to best QD structures as predicted by the QDDTs. To facilitate such a collaborative endeavor, all ESRs will be trained to use and co-develop a common data platform and they will be permanently exposed to the diversity of environments needed to implement together a QDDT. Thanks to the deep collaboration between word-leading academic beneficiaries and start-up companies in nanomaterials and computational chemistry, scientific training is complemented by extensive transferrable skills training. Moreover, the timeliness of the research and training topic – digital twins in materials science - enables the consortium to implement a proactive outreach strategy, which extends from a personal outreach activities of the ESRs to QD technology broadcasting to reach a broader field of industrial actors and policy makers and ensure the network has lasting impact on nanomaterials research and innovation.

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  • Research Project

Nanoparticles in the spotlight: light-driven nanoscience from lab to society (Nano-Light). 01/09/2024 - 31/12/2030

Abstract

Nanomaterials already have become indispensable in numerous modern technologies that impact our society. It recently became clear that their coupling with light holds significant promise for innovative developments that may open the route to novel light-driven applications in energy storage, photoelectrochemical sensing, photovoltaics, photocatalysis, drug delivery, and more. Incorporation in actual applications will, however, strongly depend on a deep understanding of the factors that influence the structure-property connection, an improved stability as well as on their technoeconomic and environmental performance. To tackle these crucial challenges, the Nano-Light consortium emerges as a unique and multidisciplinary platform. The consortium brings together extensive expertise in nanoscience covering the synthesis of photoactive nanostructures, advanced electron microscopy and X-ray characterisation, computational materials science, applied nanoengineering and techno-sustainability assessments. By combining cutting-edge (3D) transmission electron microscopy with advanced light sources and environmental holders, the consortium aims to optimize the interaction between nanomaterials and light under working conditions. Such experiments are extremely challenging, but if successful, they will yield unprecedented insights into the fundamental mechanisms governing light-matter interactions at the nanoscale. By exploiting a synergistic approach, one of the primary objectives of the consortium is to obtain comprehensive understanding on how nanomaterials absorb, scatter, emit, or manipulate light, thereby providing crucial knowledge for the design and optimization of next-generation technologies. Such understanding will be crucial for applications in which light plays a beneficial enabling role or, conversely, in scenarios where light accelerates the degradation of the behaviour of the nanomaterials. These areas include the plasmonic chiroptic nanoparticles for early disease detection, overcoming light degradation of pigments in art conservation or (perovskite) photovoltaic nanomaterials for solar cells or X-ray detectors, plasmon-enabled biosensing and light–driven drug delivery in nano-medicine applications, photo(-electro)catalytic hydrogen production or CO2 conversion. Furthermore, the consortium will develop techno-economic and environmental assessments at early technology readiness levels for the envisioned nanotechnological applications to promote safe and sustainable technological solutions. These goals of Nano-Light are in excellent agreement with the sustainable research and innovation goals put forward by the EU. As such, the research conducted under the Nano-Light consortium will strengthen the position of UAntwerp on the European map as an established nanoscience centre leading to further collaborations in the field of nanotechnology and related technologies.

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  • Research Project

Designing of multifunctional nanomaterials for light-driven innovation technologies (DELIGHT). 01/01/2024 - 31/12/2027

Abstract

DELIGHT aims at excellence of Europe in nanoscience and impact in research and development at the highest level. The project focuses on multifunctional nanomaterials based on colloidal particles, organic/inorganic perovskites, and organic and biomaterials. Design and fabrication of these materials for state-of-the-art applications requires a high level of interdisciplinarity with expertise from chemistry, physics, material science, engineering, nanofabrication and biology, combined with the most advanced spectroscopy tools. The scientific objectives of DELIGHT are to establish a platform of highly versatile functional nanomaterials, with the use of machine learning and artificial intelligence for material/device development and characterization. The focus is on multifunctional hybrids, heterostructures, and assemblies, and to fully exploit their potential for catalysis, energy, lighting, plasmonics, and theranostics. The research is organized in 3 work packages (WPs) that target nanomaterial development, functional composites and in-depth characterization, and device applications. Social and training objectives are the education of young researchers in Europe on the highest level, with emphasis on interdisciplinarity that is fundamental in modern nanoscience, the advancement of technological know-how that enables a sustainable and eco-friendly modern society, and promotion of gender equality in the scientific landscape at all levels. These goals are implemented in a WP dedicated to training, organizing lectures, workshops, technology transfer, and outreach and dissemination events. DELIGHT assembled an academic team of outstanding excellence, which links key players in the EU working on state-of-the-art nanomaterials with world leading universities in the US, Canada, and Argentina that are known for their unique scientific and technological capabilities and efficient technology transfer.

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  • Research Project

Boosting properties and stability of metal halide nanocrystals and derived heterostructures by innovative transmission electron microscopy. 01/01/2023 - 31/12/2026

Abstract

Metal halide nanocrystals (NCs) have emerged as attractive materials for applications such as displays, solar cells and medical scanners. Even though their potential impact on society is huge, commercialization is hampered by the presence of lead and the instability of the materials against e.g. heat, moisture or light. To develop novel (lead-free) NCs with optimized properties and stability, characterization of the atomic structure and composition is crucial. Transmission electron microscopy (TEM) is an ideal tool, but imaging metal halide NCs by TEM is extremely difficult because of their sensitivity to the electron beam. The project is a unique collaboration between EMAT, the electron microscopy group at the University of Antwerp, and the group of Professor Liberato Manna at IIT (Genova). The main goal is to develop innovative TEM methods that will enable us to link the structure and composition of metal halide NCs to their properties and stability. We will hereby exploit the information richness and dose efficiency of a novel technique, called 4D scanning TEM (STEM), and will identify e.g. strain, defects and new phases in metal halide NCs. Moreover, 4D STEM will be combined with in situ TEM holders, which will enable us to investigate atomistic phenomena that occur as a result of environmental triggers. We envisage that our project will lead to the preparation of new generations of NCs with improved properties and stability.

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  • Research Project

CHIral symmetry breaking from Surface to Bulk: a multidisciplinary approach of the crystallization of achiral and chiral molecules (CHISUB). 01/01/2022 - 31/12/2025

Abstract

CHISUB features a multidisciplinary approach, towards crystallization mechanisms of molecules, which uses chiral symmetry breaking as local probe of ordering phenomena and as a tool for enantiomeric separation. Crystallization often starts on surfaces of rigid substrates with the formation of 2D self-assembled molecular layers and then extends to bulk phases. CHISUB intends to design, synthesize, and characterize a library of molecular systems tailored to break chiral symmetry at different time- and length-scales. These systems will be studied by scanning probe microscopy at 2D and by electron microscopy and diffraction techniques when extending to 3D. Chiral symmetry breaking towards specific handedness will be directed by external stimuli, such as a combination of electric and magnetic fields, spin polarization, and even rotation of molecular machines. Theoretical and experimental studies will be carried out in synergy to explore ordering phenomena and chiral selectivity processes from first principles and reach a fundamental understanding beyond specific systems.

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  • Research Project

Strain to stabilize metal halide PERovSkites: an Integrated effort from fundamentalS toopto-electronic applicaTions (PERsist). 01/01/2021 - 31/12/2024

Abstract

Light detection and emission are crucial for displays, medical and security scanners. Given the societal relevance, there is an emerging need for novel opto-electronic materials with higher conversion effi-ciency and lower production cost. Metal halide perovskites are promising high-performance semicon-ductors due to their strong absorption and emission in a broad spectral range and their ease of manu-facturing. So far, integration in opto-electronic devices was hampered by inherent stability issues such as the degradation from the optically active "black" phase into an inactive phase. Based on our recent proof-of-concept, we will explore a fundamentally new paradigm to stabilize the black phase under ambient conditions. This innovative concept exploits strain engineering, with thin films fixed to sub-strates and/or patterned at the nano- to micrometer scale. PERsist builds on the synergy between leading experts in high-end micro/spectroscopy & modelling of nanomaterials.

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Quantifying the dynamics of the 3D atomic structure using hidden Markov models in scanning transmission electron microscopy. 01/01/2021 - 31/12/2024

Abstract

The aim of this project is to quantify the 3D dynamics of complex nanostructures at the atomic scale when they evolve over time via adatom dynamics, surface diffusion or during in situ experiments. This highly challenging and innovative objective will be reached by combining novel data-driven statistical methods with new image detection capabilities in aberration corrected scanning transmission electron microscopy. The ability to follow the motion of individual atoms in 3D in a realistic environment will clearly take the characterisation of nanomaterials to the next level. Quantitative 3D characterisation of nanostructures can nowadays be achieved with high reliability for systems under stationary conditions. Yet, major problems exist to get insight into the 3D dynamics because of the lack of physics-based models, detailed statistical analyses, and optimal design of experiments in a self-consistent computational framework. Machine learning using a hidden Markov model will enable us to explicitly describe structural changes as a function of time and to fully exploit the temporal information available in the observations. This unique approach will result in a precise characterisation of complex nanostructures in response to environmental stimuli such as temperature, pressure or gas composition. Clearly this is a prerequisite to understand the unique link between a material's structure and its properties, which is important for the design of a broad range of nanomaterials.

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Bringing nanoscience from the lab to society (NANOLAB). 01/01/2020 - 31/12/2025

Abstract

Nanomaterials play a key role in modern technology and society, because of their unique physical and chemical characteristics. The synthesis of nanomaterials is maturing but surprisingly little is known about the exact roles that different experimental parameters have in tuning their final properties. It is hereby of crucial importance to understand the connection between these properties and the (three-dimensional) structure or composition of nanomaterials. The proposed consortium will focus on the design and use of nanomaterials in fields as diverse as plasmonics, electrosensing, nanomagnetism and in applications such as art conservation, environment and sustainable energy. In all of these studies, the consortium will integrate (3D) quantitative transmission electron microscopy and X-ray spectroscopy with density functional calculations of the structural stability and optoelectronic properties as well as with accelerated molecular dynamics for chemical reactivity. The major challenge will be to link the different time and length scales of the complementary techniques in order to arrive at a complete understanding of the structure-functionality correlation. Through such knowledge, the design of nanostructures with desired functionalities and the incorporation of such structures in actual applications, such as e.g. highly selective sensing and air purification will become feasible. In addition, the techno-economic and environmental performance will be assessed to support the further development of those applications. Since the ultimate aim of this interdisciplinary consortium is to contribute to the societal impact of nanotechnology, the NanoLab will go beyond the study of simplified test materials and will focus on nanostructures for real-life, cost-effective and environmentally-friendly applications.

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Quantitative characterisation of nanostructures: from experimental data to precise measurements of unknown structure parameters by means of statistical parameter estimation theory. 01/10/2009 - 30/09/2025

Abstract

In the field of materials science and nanoscience, precise structure determination is important in order to understand the relation between structure and properties by comparison with theoretical ab-initio calculations. In combination with recent developments in nanotechnology, where one is able to make nanostructures with a well-chosen and controlled structure, an evolution toward materials design may be realized. The purpose of this project is to realize a breakthrough toward quantitative characterization of nanostructures. Therefore, use will be made of model-based electron microscopy. Starting from experimental data, physical parameters characterizing the structure of a material will be measured as precisely and accurately as possible. The methodology proposed in this project to obtain precise measurements of parameters is also applicable to several other branches of science, particularly those branches where one acquires data at the limit of what is physically measurable.

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Towards improved high capacity layered electrode materials for Liion batteries through atomic-level understanding of the redox reactions. 01/01/2020 - 31/12/2022

Abstract

Rechargeable Li-ion batteries are a pillar of our current technology driven society. More energy per mass unit can be stored in layered high capacity cathodes but they suffer from the voltage fade and voltage hysteresis reducing their energy efficiency. These detrimental effects mainly originate from the structural changes in the cathode material during charge and discharge. Recent developments have led to a paradigm shift, by showing that in these promising cathodes the oxygen oxidation, contributing to high capacity, is inherently linked with transition metal cation migration upon cycling. Together, they cause the voltage hysteresis and voltage fade. Gaining understanding of the complex interplay and control over both is necessary to exploit the advantages while eliminating the detrimental effects. To monitor both effects systematically and separate from the influence of the microstructure, we will synthesize new model structures with dedicated structural variations of the initial crystal structure and microstructure. We will study their structural changes upon cycling with state-of-the-art structure characterization techniques, and relate them to the electrochemical properties. This project will thus result in new viable Li-ion battery cathodes and allow the comprehensive understanding of the role of the microstructure, local structure and local valence for the stability of Li-rich layered cathodes, major candidates for future advanced rechargeable Li-ion batteries.

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High-throughput quantitative atomic resolution electron microscopy using real-time image simulations. 01/10/2019 - 31/12/2022

Abstract

The goal of my proposal is to develop a powerful method in order to evolve toward four-dimensional (4D=3D+time) quantification of nanostructures of arbitrary shape, size and atom type at the atomic scale. Therefore, novel quantitative measurement tools will be combined with aberration-corrected scanning transmission electron microscopy (STEM). Quantitative 3D characterisation of nanostructures can nowadays be achieved with high reliability for model-like systems with 1 type of chemical element present. Also for some heteronanostructures, a 3D visualisation at the atomic scale is possible using state-of-the-art STEM. However, high-precision quantification often involves a meticulous analysis using advanced methods. This impedes high-throughput analyses which are increasingly important for the study of dynamical processes induced by heating, under de flow of a selected gas, or by the electron beam. In this project, the initiation of real-time image simulations will be a giant leap forward for the 4D characterisation of nanomaterials. This highly challenging and innovative objective will be reached by introducing deep learning architectures into quantitative STEM. This unique approach will allow simulating images in real time using a fully physics-based description of the experimental intensities. The outcome of this project will deliver all necessary input for understanding and predicting the properties in complex nanostructures and their dynamical processes.

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Retrieving maximum structural information of beam-sensitive materials using low dose scanning transmission electron microscopy. 01/10/2019 - 30/09/2022

Abstract

The properties of nanomaterials are controlled by their three-dimensional (3D) atomic structure. Nowadays, quantitative methods can be used to retrieve 3D atomic structural information from two-dimensional (2D) scanning transmission electron microscopy (STEM) images of materials which can withstand high electron doses. The goal of this project is to develop quantitative methods to estimate the atomic positions, atom types, and number of atoms from 2D STEM images recorded using a low electron dose.

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Picometer metrology for light-element nanostructures: making every electron count (PICOMETRICS). 01/05/2018 - 30/04/2024

Abstract

Understanding nanostructures down to the atomic level is the key to optimise the design of advanced materials with revolutionary novel properties. This requires characterisation methods enabling one to quantify atomic structures with high precision. The strong interaction of accelerated electrons with matter makes that transmission electron microscopy is one of the most powerful techniques for this purpose. However, beam damage, induced by the high energy electrons, strongly hampers a detailed interpretation. To overcome this problem, electron microscopy will be ushered in a new era of non-destructive picometer metrology. This is an extremely challenging goal in modern technology because of the increasing complexity of nanostructures and the role of light elements such as lithium or hydrogen. Non-destructive picometer metrology will allow us to answer the question: what is the position, composition and bonding of every single atom in a nanomaterial even for light elements? There has been significant progress with electron microscopy to study beam-hard materials. Yet, major problems exist for radiation-sensitive nanostructures because of the lack of physics-based models, detailed statistical analyses, and optimal design of experiments in a self-consistent computational framework. In this project, novel data-driven methods will be combined with the latest experimental capabilities to locate and identify atoms, to detect light elements, to determine the three-dimensional ordering, and to measure the oxidation state from single low-dose recordings. The required electron dose is envisaged to be four orders of magnitude lower than what is nowadays used. In this manner, beam damage will be drastically reduced or even be ruled out completely. The results of this programme will enable precise characterisation of nanostructures in their native state; a prerequisite for understanding their properties. Clearly this is important for the design of a broad range of nanomaterials.

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Three-dimensional atomic modelling of functional nanocrystalline structures from a single viewing direction. 01/01/2018 - 31/12/2021

Abstract

The aim of this project is to retrieve the 3D atomic structure of nanocrystals from transmission electron microscopy (TEM) images acquired along a single viewing direction. This goal is extremely challenging but can be considered as a major breakthrough to investigate materials that degrade or deform during the acquisition of images along different viewing directions, such as in electron tomography. So far, 3D imaging at the atomic scale was only carried out for model-like systems, which are relatively stable under the electron beam. We envisage the combination of aberration corrected TEM with advanced statistical techniques and theoretical modelling as a groundbreaking new approach to go beyond conventional electron tomography and to perform 3D characterization at the atomic scale in a dose and time efficient manner. Our novel methodology will enable us to characterize functional materials that are very sensitive to the electron beam such as organic perovskites, colloidal semiconductors or battery materials, but will also open up the possibility to investigate the dynamics of nanoparticles during in situ measurements. Moreover, we will be able to drastically improve the throughput of electron tomography experiments, which is a prerequisite when trying to connect the structure to the functional properties. We therefore expect that the outcome of this project will deliver all necessary input to predicting properties and may even guide the synthesis of new nanostructures.

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Smart strategies to break the beam damage limits in transmission electron microscopy. 01/01/2018 - 31/12/2021

Abstract

The goal of this project is to develop and apply smart strategies, which are dedicated to characterise beam-sensitive nanostructures using quantitative scanning transmission electron microscopy imaging. This will allow one to use a minimum electron dose to detect single atoms, to determine their atom types and to precisely measure positions of atoms. In this manner, beam damage will be drastically reduced or will even be ruled out completely.

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From 2D to 3D crystals: a multi-scale, multi-technique and multisystem approach of the crystallization of organic molecules (2Dto3D). 01/01/2018 - 31/12/2021

Abstract

The occurrence of two or more crystal structures for a given molecule, a phenomenon which is called polymorphism, is ubiquitous to various classes of synthetic and natural compounds. Examples of polymorphism are known in numerous application fields, such as food, explosives, pigments, semiconductors, fertilizers, and pharmaceutical drugs. Different crystal structures, so-called polymorphs, of the same compound exhibit sometimes very different physical properties, chemical reactivity, and biological functions. For instance, the polymorphs might differ in solubility ruining the pharmaceutical effect of one or more of the polymorphs. Understanding and controlling polymorphism is therefore very important. Simple questions, such as "How many polymorphs has a given compound?" or "What drives polymorph selection?", remain unanswered yet. In this scientific context, scientists have started to explore the occurrence of substrate-induced polymorphism, i.e. the formation of polymorphs that exist only in the vicinity of solid substrates. In particular, 2Dto3D has the ambition to elucidate how positional and orientational order of molecules propagate from the substrate to the upper crystal layers. In this manner, 2Dto3D will gain a fundamental understanding of polymorphism at the interface with solid substrates.

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Dose-efficient fusion of imaging and analytical techniques in scanning transmission electron microscopy. 01/01/2018 - 31/12/2021

Abstract

The aim of this project is to realize a major breakthrough in the quantitative analysis of imaging and analytical techniques in scanning transmission electron microscopy (STEM). Therefore, we will exploit the physics-based description of the fundamental processes of electron scattering and combine this with a thorough multivariate statistical analysis of the recorded signals. In this manner, we will be able to identify the chemical nature of all individual atoms in three dimensions (3D). So far, imaging and analytical signals have been analyzed separately in STEM. Although analytical techniques are in principle well suited because of their elemental specificity, they have a much lower signal to noise ratio as compared to imaging techniques. We foresee that our multivariate method, in which new physics-based models are incorporated to describe the electron-object interaction, enables us to achieve element-specific atom counting at a local scale and to determine even the ordering of the atoms along the viewing direction. Furthermore, our approach will be optimized to reach high elemental measurement precision for a minimum incoming electron dose. This novel dose-efficient quantitative methodology will clearly usher electron microscopy in a new era of 3D element-specific metrology at the atomic scale. This will exactly provide the input needed to understand the unique link between a material's structure and its properties in both materials and in life sciences.

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Retrieving maximum structural information of beam-sensitive materials using low dose scanning transmission electron microscopy 01/10/2017 - 30/09/2019

Abstract

The properties of nanomaterials are controlled by their three-dimensional (3D) atomic structure. Nowadays, quantitative methods can be used to retrieve 3D atomic structural information from two-dimensional (2D) scanning transmission electron microscopy (STEM) images of materials which can withstand high electron doses. The goal of this project is to develop quantitative methods to estimate the atomic positions, atom types, and number of atoms from 2D STEM images recorded using a low electron dose.

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Opening up new dimensions in the study of complex nanostructures: revealing 3D atom positions, composition and dynamics. 01/10/2016 - 30/09/2018

Abstract

The goal of my proposal is to develop and design a powerful method to reconstruct 3D nanostructures on the atomic scale from single 2D STEM images. Determining the full 3D structure of heterogeneous structures will allow the identification of coreshell structures, impurities and other defect structures. This is highly desirable to understand and adequately tune functional properties. In comparison to other approaches aiming at atomic scale 3D reconstruction techniques, the proposed method relies on a simultaneous acquisition of 2D images each carrying specific information concerning the number and depth location of all atoms present. This so far unique approach of retrieving the 3D atomic structure will considerably reduce beam damage and will even enable me to introduce the fourth dimension of time in electron microscopy. In this way, it becomes possible to reveal atomic scale dynamics allowing, for example, the observation of diffusion processes and the determination of different equilibrium geometries of atomic clusters.

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Turning images into value through statistical parameter estimation 01/01/2016 - 31/12/2020

Abstract

In Flanders, different research groups are active in the field of quantitative imaging using statistical parameter estimation theory. These groups represent a wide range of disciplines including electron microscopy, magnetic resonance imaging, astrophysics, infra-red spectroscopy, X-ray and positron emission tomography. A common goal is to determine unknown parameters, which characterize the object under study, as precisely as possible from experimental images or spectra. The partners involved use the know-how and methods that are specific to their particular application. However, these methods are widely applicable and can be used for a broad range of problems. With the establishment of this network, the expertise of several research groups are combined and aims to stimulate new scientific collaborations and to facilitate the exchange of knowledge on various techniques.

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Unscrambling mixed elements with single atom sensitivity using quantitative scanning transmission electron microscopy. 01/10/2015 - 30/09/2019

Abstract

The goal of this project is to develop and design a powerful method in order to unscramble mixed element nanostructures at the atomic scale in three dimensions (3D). Therefore, novel quantitative measurement tools will be combined with aberration corrected scanning transmission electron microscopy (STEM). Visualisation at the atomic scale in 3D using state-of-the-art STEM is nowadays possible for modellike systems with 1 type of chemical element present. For this purpose counting the number of atoms in each projected atomic column is of great help. However, precise determination of the atomic structure in 3D of hetero-nanostructures is currently limited because of the lack of methods to quantitatively unscramble mixed elements. In this project, atom-counting will be performed for technologically important nanostructures that are more complex than model systems, including systems with adjacent atomic number Z such as Pt-Au, Fe-Co, and Ge-Ga-As. The aim is to quantitatively characterise the number of atoms and atom types of mixed element nanostructures with single atom sensitivity. This highly challenging objective will be reached by a unique combination of physics-based modelling and advanced statistical methods. The outcome of this project will deliver the necessary input for understanding and predicting the properties of complex hetero-nanostructures and to guide the development of new nanomaterials.

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Complex hetero-nanosystems: three-dimensional characterisation down to the atomic scale. 01/01/2015 - 31/12/2018

Abstract

The aim of this project is to quantify the structure and composition of complex heteronanostructures in three dimensions (3D) at the atomic scale. Therefore, aberration corrected transmission electron microscopy (TEM) will be combined with innovative 3D reconstruction algorithms and novel quantitative measurement tools.

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Bringing light atoms to light: precise characterization of light-atom nanostructures using transmission electron microscopy. 01/01/2015 - 31/12/2018

Abstract

The aim of this project is to detect extremely light atoms, to determine their atom types and to measure their positions down to picometer precision. Therefore, aberration corrected scanning transmission electron microscopy will be combined with innovative quantitative measuring.

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Opening up new dimensions in the study of complex nanostructures: revealing 3D atom positions, composition and dynamics. 01/10/2014 - 30/09/2016

Abstract

The goal of my proposal is to develop and design a powerful method to reconstruct 3D nanostructures on the atomic scale from single 2D STEM images. Determining the full 3D structure of heterogeneous structures will allow the identification of coreshell structures, impurities and other defect structures. This is highly desirable to understand and adequately tune functional properties. In comparison to other approaches aiming at atomic scale 3D reconstruction techniques, the proposed method relies on a simultaneous acquisition of 2D images each carrying specific information concerning the number and depth location of all atoms present. This so far unique approach of retrieving the 3D atomic structure will considerably reduce beam damage and will even enable me to introduce the fourth dimension of time in electron microscopy. In this way, it becomes possible to reveal atomic scale dynamics allowing, for example, the observation of diffusion processes and the determination of different equilibrium geometries of atomic clusters.

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TopSPIN for TEM nanostatistics. 19/05/2014 - 31/12/2018

Abstract

This project represents a formal research agreement between UA and on the other hand the Hercules Foundation. UA provides the Hercules Foundation research results mentioned in the title of the project under the conditions as stipulated in this contract.

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3D picometrology : new routes to explore the atomic arrangement using state-of-the-art electron microscopy 01/01/2013 - 31/12/2016

Abstract

The goal of this project is therefore to develop and apply quantitative methods in order to visualize and identify atoms and next to precisely measure their positions in three dimensions. This will open up a whole new range of possibilities to understand and characterize nanocrystals at the atomic level and to help developing innovative materials with revolutionary interesting properties.

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Transmission electron microscopy beyond the limits of imaging. 01/10/2012 - 30/09/2015

Abstract

The main objective of this proposal is to push aberration corrected transmission electron microscopy (TEM) toward precise measurements of unknown structure parameters. Although the resolution of these state-of-the-art instruments has greatly been improved by optimizing the lens design, equally fundamental changes in the image processing and acquisition methods are required in order to have the instrument performing at the limits of its capabilities. Therefore, use will be made of statistical parameter estimation theory. The starting-point is the availability of a parametric model describing the expectations of the images. This is a physics-based model depending on the unknown structure parameters. It describes the interaction of the electrons with the object, the transfer in the microscope, and the detection. Next, the unknown parameters are estimated by fitting this model to the experimental images using a criterion of goodness of fit. Through a combination of available techniques in TEM, the focus in this project will be to determine atom positions with picometer precision for heavy as well as for light atoms, precise chemical composition analysis, and detection of single atoms. Finally, in order to study beam sensitive matter without radiation damage, the principles of statistical experimental design will be used to determine the minimally required electron dose in order to attain a pre-specified precision.

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Quantitative three-dimensional structure determination using transmission electron microscopy : from images toward precise three-dimensional structures of nanomaterials at atomic scale. 01/01/2011 - 31/12/2014

Abstract

This project aims at the development of new measurement techniques using transmission electron microscopy in order to realize a breakthrough towards quantitative three-dimensional structure determination of nanomaterials at atomic scale.

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Transmission electron microscopy beyond the limits of imaging. 01/10/2010 - 30/09/2012

Abstract

The main objective of this proposal is to push aberration corrected transmission electron microscopy (TEM) toward precise measurements of unknown structure parameters. Although the resolution of these state-of-the-art instruments has greatly been improved by optimizing the lens design, equally fundamental changes in the image processing and acquisition methods are required in order to have the instrument performing at the limits of its capabilities. Therefore, use will be made of statistical parameter estimation theory. The starting-point is the availability of a parametric model describing the expectations of the images. This is a physics-based model depending on the unknown structure parameters. It describes the interaction of the electrons with the object, the transfer in the microscope, and the detection. Next, the unknown parameters are estimated by fitting this model to the experimental images using a criterion of goodness of fit. Through a combination of available techniques in TEM, the focus in this project will be to determine atom positions with picometer precision for heavy as well as for light atoms, precise chemical composition analysis, and detection of single atoms. Finally, in order to study beam sensitive matter without radiation damage, the principles of statistical experimental design will be used to determine the minimally required electron dose in order to attain a pre-specified precision.

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Quantitative electron microscopy: from experimental measurements to precise numbers. 01/01/2010 - 31/12/2013

Abstract

The aim of this research project is to determine unknown structure parameters such as atom positions, concentrations of atoms, atom types, and energy levels of inelastic excitations, in a quantitative way from experimental measurements obtained by means of electron microscopy. Therefore, use will be made of statistical parameter estimation theory which is expected to provide a considerable improvement in accuracy, precision and reproducibility in comparison to conventional ad-hoc methods which are currently used to extract parameters from experimental measurements.

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  • Research Project

Optimal experimental design for quantitative electron microscopy. 01/01/2008 - 31/12/2011

Abstract

The aim of this research project is to apply state-of-the-art methods from the oprimal design of experiments in the field of elektron microscopy. These methods will allow electron microscopists to evaluate, to compare, and to optimize experiments in terms of the attainable precision with which structure parameters, the atom positions in particular, can be measured. Moreover, statistical experimental design provides the possibility to decide if new instrumental developments result in significantly higher attainable precisions. The highest attainable precision determines the theoretical limit to quantitative electron microscopy.

Researcher(s)

Research team(s)

Project type(s)

  • Research Project

Model-based electron microscopy: From visual interpretation of the observations toward precise measurements of physical structure parameters. 01/10/2007 - 30/09/2009

Abstract

The aim of this project is to realize a breakthrough toward quantitative, model-based electron microscopy so as to obtain precise measurements of physical structure parameters from the observations. From theoretical as well as from experimental point of view, this is the project's goal. On the one hand, this means that the methodology will be further improved and optimized and on the other hand, it will be shown that precise measurements are attainable in practice by applying the methodology to experimental observations.

Researcher(s)

Research team(s)

Project type(s)

  • Research Project

Condor. 01/02/2007 - 31/12/2010

Abstract

The Condor project will take up research on the model driven development of systems that are governed by complex physics and have to comply with severe performance requirements. it will concentrate on systems that - incorporate intricate and delicately interrelated physics; - are very sensitive to implementation details and imperfections and to external disturbances.

Researcher(s)

Research team(s)

Project type(s)

  • Research Project

Quantitative atomic resolution electron tomography : a challenge for precise, three-dimensional, atomic structure determination of aperiodic structures. 01/01/2005 - 31/12/2008

Abstract

The aim of the project is to realize a breakthrough toward quantitative atomic resolution electron tomography in order to measure the local, three-dimensional structure of aperiodic materials as precisely as possible. For the validation of theoretical models, a precision of the atom positions of the order of 0.01 to 0.001 nm is required.

Researcher(s)

Research team(s)

Project type(s)

  • Research Project

Towards exact measurings of physical parameters by means of model-based electron microscopy. 01/10/2003 - 30/09/2007

Abstract

Researcher(s)

Research team(s)

Project type(s)

  • Research Project