Research Sara Bals

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.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: Van Aert Sandra

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Metal halide perovskites (MHPs) are highly promising semiconductors for novel optoelectronic devices. A timely goal is to extend the use of MHPs to chiroptoelectronic applications, such as circularly polarized light photodetectors. Due to the flexibility of arranging the organic and inorganic building blocks in perovskites, it recently became possible to synthesize chiral perovskites with a non-centrosymmetric crystal structure. In my project I will focus on MHP nanocrystals (NCs) containing chiral cations and MHP NCs assembled in a three-dimensional chiral morphology. For both systems, the chirality transfer mechanisms are not yet understood. Therefore, the aim of my project is to exploit advanced transmission electron microscopy (TEM), including 4D scanning TEM, electron tomography and electron diffraction to quantify the helicity of self-assembled structures and the occurring distortions of the inorganic framework in MHPs with chiral cations. Due to the high beam sensitivity of MHPs and organic cations the development of novel low-dose techniques will be crucial. The insights on chiral MHPs, obtained from this project will pave the way to design novel chiroptical devices.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Schrenker Nadine

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Proton exchange membrane fuel cells (PEMFCs) are poised to enable a decarbonized heavy-duty mobility, but progress towards lower platinum requirements remains needed. The optimization of the high surface area, nanoporous, carbons that supports the Pt nanoparticles in the cells is a particularly promising pathway to achieve high Pt utilization and efficiency. Yet, characterizing, simulating, and therefore manipulating these carbons has proven difficult due to their three-dimensional (3D), nanoscopic, and highly heterogeneous nature. In this project, I will use advanced electron microscopy methods for 3D and in situ characterization and link them with atomistic simulations in order to uncover the multiscale porous structure the carbon supports from the atomic to the primary particle level. Specifically, I will reveal i) the atomic structure of the pores in carbon supports, ii) the morphological descriptors or the pore network and their relationships to transport resistances, and iii) the structural changes that improve PEMFC performance. The results will provide insights into the origins of performance losses, deliver novel knowledge and datasets for enhanced accuracy in modeling, and therefore contribute towards high-power, low-Pt, PEMFCs. This project will further benefit the other applications of porous carbons, including heterogeneous catalysis, batteries and supercapacitors, and provide innovative methods to characterize the next generation of carbon and energy materials.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Girod Robin

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

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.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: De Wael Karolien
• Co-promoter: Janssens Koen
• Co-promoter: Milosevic Milorad
• Co-promoter: Van Aert Sandra
• Co-promoter: Van Passel Steven
• Co-promoter: Verbruggen Sammy

Research team(s)

• Electron microscopy for materials research (EMAT)

Project website

Project type(s)

• Research Project

Abstract

Electron microscopy is a powerful tool for characterizing nanomaterials at the atomic scale. However, small nanoclusters are particularly susceptible to electron beam activation due to their high surface-to-volume ratio and sensitivity to energetic electrons1. The interaction between the electron beam and nanoclusters can induce mobility and structural changes2, compromising the accuracy of dynamic in situ studies. Here, we aim to quantitatively analyze the electron beam-induced restructuring of small nanoclusters and develop strategies to mitigate this effect by investigating different experimental parameters such as beam energy, sample environment, and low-dose imaging techniques. Implementing these advanced imaging and analysis techniques will help us understand the electron beam effect on the clusters and study their dynamics under controlled in situ conditions. In addition, we propose to delve deeper into the behavior of nanoparticles on solid surfaces under applied electric fields through in situ biasing experiments. Understanding how nanoparticles respond to electric fields on a solid substrate is crucial for various applications, including catalysis, sensing, and nanoelectronics3. By applying controlled electric fields during electron microscopy imaging, we can explore the dynamics of nanoparticle assembly and reconfiguration under external stimuli. Furthermore, to facilitate comprehensive 3D investigations of these assemblies, we plan to develop a novel tomography biasing chip that enables us to probe the three-dimensional architecture of nanoparticle assemblies in real-time, providing valuable insights into their structural evolution and response to external stimuli.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Balalta Deema

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Scanning Transmission Electron Microscopy (STEM) Energy Dispersive X-ray (EDX) analysis were done successfully by an EMAT operator on the Osiris TEM under supervision of a TEM operator of UGent duing one day.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Metal nanoparticles with asymmetric morphologies have gained increasing scientific interest, because of the possibility to tune their interaction with (polarized) light. Hereby, the optical activity is closely related to the three-dimensional shape of the nanomaterial. However, quantifying morphological features of nano-objects is extremely challenging. Electron tomography enables one to retrieve the three-dimensional morphology of nanomaterials, so far but only a qualitative analysis of the morphology of nanoparticles was made. A method to quantify the helicity of complex nanomaterials at the single particle level starting from high-quality electron tomography reconstructions was recently proposed. However, in order to provide significant insights into the fundamental origin of optical properties, new techniques for high throughput three-dimensional data acquisition are required. This project seeks to develop such approaches, based on the flexibility of modern aberration corrected transmission electron microscopes in combination with advanced computational techniques.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Novel electrolyser technologies that improve cost-efficiency through reductions in electricity and component costs will be needed for delivering hydrogen from renewables at scale. In this project we aim to develop a breakthrough photoelectrolysis device that will (a) reduce the electricity demand of clean hydrogen production; (b) eliminate use of critical raw materials (CRM) in electrodes/electrocatalysts; and (c) couple hydrogen generation to valorization of a biomass- derived stream, thus improving technoeconomic performance and circularity. The aim is to deliver plasmon-enhanced, hybrid photoelectrolysis under alkaline conditions for hydrogen generation. Cell voltages will be lowered, first, via replacement of oxygen evolution at the anode with an organic oxidation reaction (OOR) that will offer thermodynamic advantages, benefits associated with component and operational costs and added-value chemicals from bio-waste via selective anodic processes. Second, photoelectrolysis enhanced by plasmon-ENZ (Epsilon Near- Zero) systems will be adopted to reduce cell overpotential and enhance energy efficiency. Third, computationally guided design of CRM-free plasmon-enhanced electrocatalysts will enable delivery of activity and selectivity without reliance on precious and/or scarce metals. We will demonstrate breakthrough improvements relative to state-of-the-art using three key performance indicators defined to accurately reflect trade-offs in energy efficiency and cost arising from the OOR and from materials choices that depart from state-of-the-art, while weighting the benefits of a transition to CRM-free strategies and consequent improvements in criticality. The mainstreaming of technoeconomic and life cycle analysis will guide materials choices to deliver a prototype CRM-free photoelectrolyser at lab scale, and will chart a path to cost-competitive application scenarios for exploitation beyond proof-of-concept. Within this project, the UAntwerp partner will particularly focus on the synthesis of noble metal- free plasmonic nanostructures based on ZrN, and explore new types of photoelectrochemical cell design. In close interaction with the EnvEcon research group, a detailed techno-economic assessment will be performed, which will reveal the best opportunities towards valorization. Unique in the setting of the valorization roadmap is that not only cost reductions in device construction or sales volumes of produced hydrogen will be accounted for, but also profits made by up-conversion of bio-waste streams used a the feed, and environmental and related cost impacts by avoiding the use of critical raw materials.

Researcher(s)

• Promoter: Verbruggen Sammy
• Co-promoter: Bals Sara
• Co-promoter: Nimmegeers Philippe
• Co-promoter: Van Passel Steven

Research team(s)

• Antwerp engineering, PhotoElectroChemistry & Sensing (A-PECS)

Project type(s)

• Research Project

Abstract

Future technological innovations in areas such as the Internet of things and wearable electronics require cheap, easily deformable and reasonably performing printed electronic circuitries. However, current state-of-the-art (SoA) printed electronic devices show mobilities of ~10 cm2/Vs, about ×100 lower than traditional Si-electronics. A promising solution to print devices from 2D semiconducting nanosheets gives relatively low mobilities (~0.1 cm2/Vs) due to the rate-limiting nature of charge transfer (CT) across inter-nanosheet junctions. By minimising the junction resistance RJ, the mobility of printed devices could match that of individual nanosheets, i.e., up to 1000 cm2/Vs for phosphorene, competing with Si. HYPERSONIC is a high-risk, high-gain interdisciplinary project exploiting new chemical and physical approaches to minimise RJ in printed nanosheet networks, leading to ultra-cheap printed devices with a performance ×10–100 beyond the SoA. The chemical approach relies on chemical crosslinking of nanosheets with (semi)conducting molecules to boost inter-nanosheet CT. The physical approach involves synthesising high-aspect-ratio nanosheets, leading to low bending rigidity and increased inter-nanosheet interactions, yielding conformal, large-area junctions of >10e4 nm2 to dramatically reduce RJ. Our radical new technology will use a range of n- or p-type nanosheets to achieve printed networks with mobilities of up to 1000 cm2/Vs. A comprehensive electrical characterisation of all nanosheet networks will allow us to not only identify those with ultra-high mobility but also to fully control the relation between basic physics/chemistry and network mobility. We will demonstrate the utility of our technology by using our best-performing networks as complementary field-effect devices in next- generation, integrated, wearable sensor arrays. Printed digital and analog circuits will read and amplify sensor signals, demonstrating a potential commercialisable application.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Using Focused Ion Beam Scanning Electron Microscopy ten electron transparent lamellas for Transmission Electron Microscopy of targeted regions of interest are prepared of different materials on request.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Research in the fields of nanoscience and nanotechnology is vital for sustainability globally: advancement in nanoscience and nanotechnology cannot be achieved without using research infrastructures (RI). RIANA encompasses 7 European networks of top-level RIs to cover the most advanced techniques relevant for synthesis, nanofabrication, processing, characterization, analytics, as well as simulation capacity. Highly customised and efficient access to 69 infrastructures is coordinated via a single-entry point and enabled through comprehensive Science and Innovation Service by senior scientists, experts for the transfer of technology from academia to industry, and highly trained Junior Scientists. The Junior Scientist boost RI experience to an entirely new level: they provide customised Science Service supporting users from initial ideas to hands-on experiments, data analysis and dissemination of results to generate the greatest impact from access to world-class RI. This core of RIANA is aligned to attract experienced and new users from academia or industry making their promising ideas a success and push them to higher TRL. RIANA is flexible to upcoming emergent scientific topics and needs: together with stakeholders from the nanocommunity, RIANA implements the opportunity to offer flexible access to additional infrastructures in, and even outside of Europe beyond the current consortium, and to direct the Science Service towards evolving user needs via additional specialised Junior Scientists. Based on the four years of experience, the RIANA consortium will develop a roadmap for the future of the nanoscience and nanotechnology at European RIs.

Researcher(s)

• Promoter: Verbeeck Johan
• Co-promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

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.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: Covaci Lucian
• Co-promoter: Milosevic Milorad
• Co-promoter: Van Aert Sandra
• Co-promoter: Verbruggen Sammy

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Electron tomography is an invaluable tool for characterizing the 3D structure of nanomaterials. Recently, there has been significant progress towards the real-time and fast approaches for determining 3D morphology of nanoparticles. These include quasi-3D imaging [1] morphology imaging with secondary electron beam induced current (SEEBIC)[2] and fast tomography.[3] However, these techniques on their own are insufficient for bulk analysis of material properties or characterization of samples with structures that alter rapidly such as beam sensitive MOFs and perovskites. Herein we wish to investigate the use of these techniques in combination with computational techniques such as real-time neural radiance fields (NERFs), and machine learning[4] to perform real-time analysis of time sensitive nanomaterials. One such avenue would be to utilize fast tomography with NERFs to extract quickly extract a 3D scene which can be converted to a 3D volume for further analysis or to use machine learning with Fourier domain filters and multiprocessing to obtain real-time low resolution reconstructions for analysis while computing higher resolution reconstructions.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Craig Tim

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The overarching goal of the project is to develop an in-line material-monitoring setup in a production line using recycled materials as raw materials. In order to develop an in-line material-monitoring setup based on machine learning, the training data should contain a wide range of data related to specific material characteristics such as composition, crystal phase, size and shape. Electron microscopy can provide this information on the micro- to nanometre scale and will serve as ground truth data for machine learning approaches. For every subset of data, there is a specific microscope setup, detector and processing methodology involved. Using electron microscopes, the information is inherently coming from a very local area of the material, on the micro- to nanometre scale, and it is therefore a challenge to do high-throughput analyses. The aim of the project is to initiate the development of high-throughput methods for multiscale and multimode characterization of recycled materials. Depending on the recycled materials and their envisioned usage in future products, different descriptors will be relevant. For example, descriptions with various levels of accuracy of crystallinity, composition, or morphology at different scales would be differently relevant for e.g. recycled battery materials or concrete. In recycled cathode materials, the crystallinity of the oxide matrix and the nature of contaminating coatings will greatly influence the performance. Alternatively, the properties of recycled concrete materials will greatly depend on the porosity, morphology and texture at the micro and nanoscale.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Metal halide perovskites (MHPs) are promising for light emitting diodes (LEDs) due to their high color purity, band gap tunability and low cost of fabrication. However, their actual commercial use in LEDs is hindered by insufficient external quantum efficiency and instability to external triggers including heating, moisture and oxygen. I will therefore develop well-organized self-assemblies of MHP nanocrystals, for which the stability is expected to be majorly improved, due to the close packing and the doping of individual nanocrystals. In addition, the collective properties of the assemblies are envisaged to result in enhanced efficiency. Consequently, highly uniform, optically active and stable active layers for LEDs will be obtained. The synthesis and assembly will be guided by iterative measurements of the optical properties together with a detailed characterization by quantitative transmission electron microscopy (TEM). 3D characterization will allow me to extract quantitative descriptors to evaluate the packing of the nanocrystals, whereas in situ TEM studies will enable me to understand the degradation behavior so that my project will open the route to the incorporation of assemblies of MHP nanocrystals in the next generation of LEDs. I therefore aim at proving the use of self-assembled MHPs for LEDs in an experimental proof-of-concept (TRL 3) up to a technology validated in the laboratory (TRL 4).

Researcher(s)

• Promoter: Bals Sara
• Fellow: Skvortsova Irina

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

By means of Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) thin electron transparent lammela's are being prepared that can be studied by High-Resolution Transmission Electron Microscopy (HR-TEM).

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Transmission electron microscopy (TEM) is a powerful technique to fully characterise the local structure of a broad range of materials. Due to many recent hardware advances, the quality of TEM measurements is nowadays ultimately determined by the sample supports. Surprisingly though, their importance has been majorly overlooked so far. The many benefits of graphene layers as a support have been well-recognised by the community, but commercial "graphene grids" show poor coverage and are dominated by unwanted residues and Cu nanoparticles from the preparation process. Consequently, commercial graphene grids currently correspond to merely 1% of the grids used. A solution to this problem is a novel protocol to produce high-quality graphene grids, developed within my ongoing ERC Consolidator grant "REALNANO". A head-to-head comparison with the state-of-the-art demonstrates the superior quality of the HYPERGRAPH grids. Moreover, our ongoing market survey with leading groups in both materials and life science indicates a very strong need for graphene gridsthat yield high and constant quality. Therefore, the overall aim of this PoC isto deliver our HYPERGRAPH supports to the TEM community, our beachhead market. To reach this goal, our methodology is based on further product development (reproducibility, cost-efficiency and shelf-life), exploration of other possible applications and business planning. In this manner, we aim to increase the Technology Readiness Level for HYPERGRAPH from 4 to 7 and the and Commercial Readiness Level from 4 to 6. Feeling the "pain" related to the poor quality of TEM supports as an end user every day, I am convinced that valorisation of our technology can fill a crucial void in the TEM value chain. In this manner, HYPERGRAPH will enable characterisation and further development of new generations of nano- and biomaterials, with applications in fields as broad as catalysis, medicine, protein research, viral infections and energy.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Graphene and related materials have high potential to be incorporated in a variety of devices because of their high electric and thermal conductivity. However, actual use in real applications demands a thorough understanding of the connection between the physical properties and deviations from the ideal structure. To gain such understanding, a local characterization, by electron microscopy is required. Unfortunately, graphene and multilayers hereof are very sensitive to the electron beam. Therefore, we will exploit novel developments in the field to apply low-dose electron microscopy techniques. The limits of these techniques will be explored, which will be of importance for several ongoing collaborations and future Horizon Europe project applications.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

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.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: Van Aert Sandra

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The project will build upon recent work regarding the development of graphene grids for TEM, supported by new transfer techniques. The availability of graphene grids within EMAT has enabled a series of experiments that were previously not possible due to a lack of necessary TEM support. This gives us the opportunity to explore the potential of using graphene grids for the characterization of the proposed materials. The results of this project are important for users from several domains, such as materials science, life science, or in situ electron microscopy. In terms of licensing opportunities, this research is relevant for three main groups of candidate companies: the current suppliers of TEM graphene grids, manufacturers of in situ TEM holders, and a group of companies that have recently become active in the cryoTEM market focusing on Single Particle Analysis.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

DYNASTY's primary objective is to build in the European South East, and in particular in the Foundation for Research and Technology Hellas (FORTH) in Crete, a significant pole of attraction for nanomaterials researchers and scientists. This will be accomplished through joint research activities and partnering with two well-established European research teams, which are in the forefront of nanomaterials research. The activities will contribute in scientific production that will motivate and attract young scientists in nanomaterials (e.g. 2D materials) science and technology. The partners include: (a) the University of Antwerp (UA) with strong expertise in advanced Electron Microscopy for Materials Science and in Condensed Matter Theory (the EMAT and CMT groups, respectively), which are both part of the UA NANOlab Center of Excellence (Belgium) (b) and the National Institute of Applied Sciences (INSA- University of Toulouse), with deep expertise in advanced spectroscopic characterization techniques of 2D materials. The activities involve training through cross-lab visits, workshops, short courses, joint conferences, and well-designed communication activities to attract young scientists at FORTH. All teams will provide their expertise and collaborate to build advanced Imaging and Spectroscopy expertise at FORTH (combining non-linear and time-resolved optical spectroscopies) that will provide precise fine structural analysis of 2D materials and their heterostructures. By the end of the three-year project, FORTH will gain advanced skills in nanomaterials characterization and knowhow in nanoelectronic devices fabrication. As a result, DYNASTY will create a collaborative platform for widening experimental networks among nanomaterials labs in Europe, enabling local teams to produce excellent interdisciplinary nanoscience, currently lacking in Greece.

Researcher(s)

• Promoter: Verbeeck Johan
• Co-promoter: Bals Sara
• Co-promoter: Covaci Lucian
• Co-promoter: Milosevic Milorad

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Therapeutic drug monitoring (TDM) has the potential to improve patients' quality of life and reduce the healthcare burden. Current TDM methods rely on embedded sensors in catheters or painful venous blood extraction with the analysis in centralised laboratories. This explains the need for non-invasive and real-time TDM through wearable and portable electrochemical devices. However, low limits of detection and continuous monitoring are still unsolved issues, with the biofouling process occurring at the electrode's surface being the main bottleneck. Therefore, the exploration of nanoporous gold (np-Au) as a functional material in microneedles (MN) will provide anti-biofouling features while exhibiting excellent analytical performance. Indeed, protein adsorption (the main cause of biofouling) only occurs at the outer level of the nanoporous material leaving most of the electroactive sites available for the electrochemical process. Microsen will elucidate: 1) the fundamental electrochemical processes at a nanoporous surface, 2) the relationship between the np-Au structure and protein adsorption, and 3) the enhanced electrocatalytic activity of the target molecules, methotrexate and esketamine, using np-Au. By doing, Microsen will introduce novel MN sensors for methotrexate and esketamine to allow long-term monitoring for painless TDM in chemotherapy and depression treatment respectively.

Researcher(s)

• Promoter: De Wael Karolien
• Co-promoter: Bals Sara
• Fellow: Parrilla Pons Marc

Research team(s)

• Antwerp engineering, PhotoElectroChemistry & Sensing (A-PECS)

Project type(s)

• Research Project

Abstract

The main goal of TEMPEL is to develop a new electrolyser that will be able to produce hydrogen from steam and low temperature waste heat. EMAT will characterise the newly developed materials using SEM and TEM.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The main purpose of the CLUE-innovationproject is the development of an efficient electrolyzer for longterm electrochemical conversion of CO2 to ethylene under realistic and industry relevant CO2 streams and using efficient electrodes based on mono- and bimetallic clusters.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Metal-organic frameworks (MOFs) are porous crystalline materials with tailorable chemistry. Their excellent properties are of interest for energy storage devices, gas adsorption and separation, catalysis, drug delivery, and many others. However, there are still many open fundamental questions about their nature and interactions with the surroundings, which could only be answered with in situ transmission electron microscopy (TEM) at the atomic scale. Unfortunately, due to their sensitivity to the electron beam, such studies are highly challenging or even impossible when 3-dimensional (3D) imaging is required. Here, I envision the combination of advanced TEM and dedicated 3D reconstruction algorithms as a groundbreaking new approach to reliably characterize the 3D structure of MOFs under realistic conditions. Visualizing the framework structure of MOFs, including defects and interfaces at high temperature and in a gas is extremely challenging, but will lead to a wealth of new information since deviations from a perfect structure have crucial impact on the properties. My objectives will enable the understanding at the atomic level of reasons behind thermal and moisture degradation of MOFs. My project will provide the much needed understanding of the fundamentals for better engineering of MOFs. Finally, I envision that the newly developed methodologies will also enable imaging of a broad class of nanomaterials that could not be studied by TEM so far because of beam sensitivity.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Kavak Safiyye

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Recently, Prof. Masuhara's group reported a new phenomenon in the optical capture of nanoparticles: particles move like a swarm outside the focus! The effective irradiation area in the optical trap is increased by multiple photon scattering from the formed (nano/micro) assembly. This phenomenon is now called 'Optically Evolved Assembling'. Phenomenologically, the optically evolved assembly/swarm is easy to understand: initially a limited number of nanoparticles are attached to the interface, well within the focal volume, resulting in a small swarm. The captured NPs scatter the light in the optical trap, increasing the out-of-focus optical potential. This allows new nanoparticles to catch up in the swarm and enhance the effect. The concept of "Optically Evolved Assembling" is completely new and has a lot of (practical) potential for light-induced material production in the future. Indeed, achieving a level of control over the nanoscale self-organized collective motion in liquid environments, similar to what has been achieved when manipulating nanoscale objects on surfaces and in high vacuum environments, could revolutionize many aspects of nanotechnology and colloidal science. This scientific research network aims to develop a comprehensive model for the "Optically Evolved Assembling" formation at the nanoscale that goes beyond the intuitive understanding we now have. Optical (scattering, gradient and absorption) forces are at the heart of the observed assemblages/swarms, but the hitherto unexplored hydrodynamic effects probably also play a crucial role. To map these, we will perform super-resolution optical imaging of the different dynamic assemblies under different optical capture conditions to unravel the individual and collective motion of the particles in the assemblage/swarm. We will compare the obtained experimental information with calculated theoretical models and simulations to further prove our developed models.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

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.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: Van Aert Sandra
• Co-promoter: Verbeeck Johan

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The European Training Network CATCHY provides a concerted effort to design novel high-performance thermo- and electrocatalysts for the conversion of CO2 into added-value synthetic fuels, while delivering a unique range of training opportunities providing young researchers with the expertise and skills required by employers in nanotechnology. Catalysis research is dedicated to the understanding and optimization of existing catalysts and the tailor-made design of new materials with a focus on high-activity, high-selectivity, and economic feasibility. CATCHY will tailor new high performance CO2 conversion catalysts by a new multidisciplinary catalysis-by-design approach combining: i. production of bimetallic gas phase clusters of controlled homogeneity mixing transition, noble, and post-transition metals and deposition on various supports; ii. extensive characterization of their morphology (ex situ and in situ) ; iii. fundamental experimental and theoretical reactivity studies; and iv. (electro)catalytic laboratory tests. A prototype of the most promising electrocatalyst will be tested under realistic operative conditions. CATCHY offers an interactive training approach combining new capabilities for the fabrication and characterization of cluster-based nanostructured surfaces to produce innovative applications. A complementary academic and industrial environment ensures an intersectorial training programme. Industry oriented training will be provided by focusing on selected catalysis applications directly related to energy and climate change issues of paramount importance to the EU and the world. The balanced program combines local expert training by academia and industrial partners, a networkwide secondment scheme, and network-wide training. The societal and environmental urgency to mitigate adverse climate change effects in the coming decades, and the particular advanced catalyst design approach, will guarantee the employability of CATCHY's young researchers.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: Altantzis Thomas

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The properties of nanomaterials are essentially determined by their three dimensional (3D) structure. Electron tomography currently enables one to measure the morphology and composition of nanostructures in 3D, even with atomic resolution. Strikingly however, these measurements are always performed at room temperature and in ultrahigh vacuum, which are conditions that are completely irrelevant for the use of nanoparticles in real applications. Moreover, nanoparticles often have ligands at their surface, which form the interface to the environment. They influence the growth, thermal stability and drive self assembly. Surprisingly, their exact role has not yet been completely understood and so far, their presence has been completely neglected during electron microscopy investigations. The aim of this program is to overcome these crucial limitations and to enable a deep understanding of the effect of a relevant climate on the structure-property connection of a broad range of nanoparticles and their assemblies. Since two dimensional in situ electron microscopy experiments are simply not sufficient to understand the complex 3D changes in anisotropic nanosystems, I will develop innovative 3D characterization tools, compatible with the fast changes of nanomaterials that occur in a thermal and gaseous environment. To visualize surface ligands without damaging their structure, I will combine direct electron detection with exit wave reconstruction techniques. Tracking the 3D structure of nanomaterials in a relevant climate is an extremely ambitious goal. However, the preliminary experiments in this application demonstrate the enormous impact. Our objectives will enable 3D dynamic characterization of reshaping of nanoparticles, important to improve thermal stability during drug delivery, sensing, data storage or hyperthermic cancer treatment. We will provide quantitative 3D measurements of the coordination numbers of the surface atoms of catalytic nanoparticles and follow the motion of individual atoms live during catalysis. By visualising surface ligands and their interface with nanoparticles in 3D, we will understand their fundamental influence on particle shape and during self assembly. This program will be the start of a completely new research line in the field of 3D imaging at the atomic scale. Even more essential is that the outcome of these challenging studies will certainly boost the design and performance of nanoparticles. This is not only of importance at a fundamental level, but is a prerequisite for the incorporation of nanomaterials in our future technology.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

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.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: De Wael Karolien
• Co-promoter: Janssens Koen
• Co-promoter: Lenaerts Silvia
• Co-promoter: Milosevic Milorad
• Co-promoter: Neyts Erik
• Co-promoter: Van Aert Sandra
• Co-promoter: Van Passel Steven
• Co-promoter: Verbruggen Sammy

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Using microtomy, thin slices of 60, 80 and 100 nm are made of an NiCrFe alloy. The sample preparation was successful. The slices will be used for synchrotron STXM measurements by the Universiteit Gent.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Bals Sara
• Promoter: Van Tendeloo Staf

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Characterisation of biopolymers using low-dose secondary electron and backscatter electron imaging in an environmental scanning electron microscope. The analysis frame in the study of transition metal recovery processes in waste waters.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Chiral features in metal nanoparticles (NP) result in chiroptical properties, of interest to many applications, such as enantioselective catalysis or separation, chiral sensing or drug delivery. These applications arise from the different interactions of chiral plasmonic NPs with left- and right-handed circularly polarized light (CPL). Therefore, much effort has been put into the development of NPs with complex structures and morphologies. The properties of such nanomaterials are usually characterized by measuring their circular dichroism (CD), which quantifies the interaction of an ensemble of particles with CPL. Multiple factors can be at the origin of the recorded CD signal, such as a helical morphology, chiral features in the crystalline structure, or the presence of chiral molecules at or near the surface of the chiral NPs. Unfortunately, there is no consensus on the relative importance of these different aspects. To obtain NPs with tailored chiroptical properties, it is thus important to understand the connection between the CD signal and the NP morphology. Transmission electron microscopy (TEM) is an excellent technique to investigate the structure of nanomaterials. Several approaches, within the field of expertise of EMAT, can be used to investigate the morphology, structure or properties of chiral nanoparticles. Examples include 3D structural characterization by scanning electron microscopy (SEM), electron tomography in real and reciprocal space and electron beam induced current measurements (SEEBIC). Moreover, there is still debate in the field on the application of electron energy loss spectroscopy (EELS) to measure chiral features of nanoparticles. Although these techniques are already being developed at EMAT in the framework of other projects, their combined application to chiral nanoparticles will require further development. For example, identification of chiral surface facets is currently impossible due to a lack of 3D resolution by electron tomography or SEEBIC. Visualisation of chiral molecules and micelles that lie at the origin of the growth of chiral nanoparticles is another challenge that will require the development of low-dose imaging techniques, ideally combined with in situ TEM to generate a relevant, liquid, environment. Moreover, quantification procedures, e.g. to define the degree of helicity will need to be developed. Such computational techniques, eventually based on the use of training a neural network as well as modeling of the connection between structure and properties are challenging aspects but the knowhow to help talented postdocs to overcome current limitations is available at EMAT.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: Lamoen Dirk
• Co-promoter: Verbeeck Johan
• Fellow: Mychinko Mikhail

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Inorganic nanoparticles and nanostructures with complex morphologies have gained increasing scientific interest, because of the possibility to tune their ability to interact (polarized) light. In some cases, the optical activity is hypothesized to originate from a specific morphology of the nanomaterial. However, quantifying the morphology of objects with sizes of tens of nanometers is far from straightforward. Electron tomography offers the possibility to faithfully retrieve the three-dimensional morphology of nanomaterials, but only a qualitative interpretation of the morphology of nanoparticles has been possible so far. I recently introduced a method to quantify the helicity of complex nanomaterials at the single particle level starting from high-quality electron tomography reconstructions. However, in order to provide significant insights into the fundamental origin of optical properties, further progress is required. Therefore, I will apply quantitative electron tomography (EMAT, University of Antwerp) and perform ensemble and single particle VIS-NIR spectroscopy (AMOLF Institute, Amsterdam). By combining these results, I will carry out a systematic investigation of different types of nanoparticles prepared in the group of Professor Luis Liz-Marzán (CICBiomagune, San Sebastián). I envisage that I will provide critical feedback to improve the synthesis and the optical activity of these exciting materials.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Heyvaert Wouter

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

By using Focussed Ion Beam - Scanning Electron microscopy and Transmission Electron Microscopy - Energy Dispersive X-ray diffraction the interaction between Al2O3 and polyimide layers has been studied.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

By using Transmission Electron Microscopy - Energy Dispersive X-ray diffraction, the location of silver nanoparicles was studied in zeolite samples. The samples have been crushed as preparation for TEM.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Dedicated TEM imaging techniques have been used in order to determine the location and size distribution of silver nanoparticles in zeolites. TEM tomography was used in order to do this characterisation in 3D.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The goal of the FUNY project is to functionalise powders in order to improve for example their adhesive or dispersive characteristics, or their hydrophobicity or hydrophilicity, depending on tthe industrial application.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Metal halide perovskites (MHP) are promising semiconductors for the next generation of optoelectronic applications because of their excellent performance and low-cost processability. Unfortunately, applications are hampered by the lack of stability when MHPs are exposed to relevant conditions. To overcome this limitation, precise knowledge of the structure-property relationship in MHPs is required. Therefore, this project aims to develop novel and advanced transmission electron microscopy (TEM) techniques for in situ experiments, during which MHPS will be exposed to environmental conditions. Hereby, the development of low dose TEM techniques is crucial because of the high electron beam-sensitivity of MHPs. These techniques will be combined with in situ experiments under heat, gaseous environment, and high bias. Based on the outcome of my experiments, I will be able to provide a better understanding of promising stabilization methods such as interfacial clamping. I will hereby reveal the influence of interfacial defects and grain boundary types in textured MHP thin films. Moreover, the local results obtained by TEM will yield novel insights on degradation mechanisms under high bias, oxygen or moisture. In this manner, my project will provide the necessary input to trigger novel strategies for long-term stability of MHPs.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Schrenker Nadine

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The overarching goal of MUMMERING is to create a research tool that encompasses the wealth of new 3D imaging modalities that are surging forward for applications in materials engineering, and to create a doctoral programme that trains 15 early stage researchers (ESRs) in this tool. This is urgently needed to prevent that massive amounts of valuable tomography data ends on a virtual scrapheap. The challenge of handling and analysing terabytes of3D data is already limiting the level of scientific insight that is extracted from many data sets. With faster acquisition times and multidimensional modalities, these challenges will soon scale to the petabyte regime. To meet this challenge, we will create an open access, open source platform that transparently and efficiently handles the complete workflow from data acquisition, over reconstruction and segmentation to physical modelling, including temporal models, i.e. 3D "movies". We consider it essential to reach this final step without compromising scientific standards if 3D imaging is to become a pervasive research tool in the visions for Industry 4.0. The 15 ESRs will be enrolled in an intensive network-wide doctoral training programme that covers all aspects of 3D imaging and will benefit from a varied track of intersectoral secondments that will challenge and broaden their scope and approach to research.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Chen Qiongyang

Research team(s)

• Electron microscopy for materials research (EMAT)

Project website

Project type(s)

• Research Project

Abstract

Transmission electron microscopy is an indispensable characterization tool for many applications in materials and life science. During the last 2 decades, enormous progress was made concerning aberration correctors, novel detectors and samples holders. Still, there is a lot of room for further improvement of TEM experiments by optimizing the carbon support grids that are hereby used. Graphene grids have the potential to bring TEM measurements of low-contrast and beam sensitive samples to the next level. Unfortunately, while being relatively expensive, the quality of commercially available grids is extremely poor. The aim of HYPERGRAPH is to produce high quality graphene grids yielding high coverage, extreme flatness and cleanness at a cost that is at least 4 times lower than what is the current standard. We will also improve throughput, reproducibility and shelf live. This project will bring a variety of TEM investigations to a next level. In this manner, HYPERGRAPH will be of crucial importance for the further development of (nano)materials in fields as broad as catalysis, sensing, medicine and energy applications.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The ARCLATH-2 project aims to overcome current drawbacks in hydrogen transportation and storage by developing a radically new transportation and storage concept based on clathrates. After a year of research, ARCLATH-1 already provided a proof of concept that shows hydrogen can indeed be encapsulated in clathrates under technically and economically relevant conditions, in terms of both pressure and temperature. A follow-up project ARCLATH-2 has now been initiated to maximise the hydrogen storage capacity of the clathrates under similar pressure and temperature conditions. At the same time, ARCLATH-2 will define a practical process of reversible hydrogen storage and delivery based on pressure swing cycling at lab-scale.

Researcher(s)

• Promoter: Cool Pegie
• Co-promoter: Bals Sara
• Co-promoter: Lenaerts Silvia
• Co-promoter: Perreault Patrice
• Co-promoter: Verbruggen Sammy

Research team(s)

• Laboratory of adsorption and catalysis (LADCA)

Project type(s)

• Research Project

Abstract

The 4D characterisation of nanoparticles, i.e., the time evolution of their 3D structures, is essential to understand their transient behaviour under external stimuli such as temperature and pressure. A recent revolution in transmission electron microscopy has made it possible to perform in-situ tomography experiments; hence 4D imaging is within reach. However, novel computational tools are urgently required since the conventional imaging methods fail to produce stable 4D images. 4D-ATOM will develop algorithms and computational techniques to enable 4D imaging of nanoparticles using compressed shape sensing. In particular, 4D-ATOM will construct a numerical scheme based on a dynamic level-set method to track the changes in nanoparticles during their heating or chemical transformations. Moreover, 4D-ATOM will design compressive measurement patterns to facilitate ultra-fast in-situ electron tomography for imaging beam-sensitive nanoparticles. The results of 4D-ATOM will be state-of-the-art in nanotechnology and open up an entirely new set of exciting experiments in the field of electron tomography. These tools will enable researchers to understand and overcome degradation mechanisms for sensitive structures such as metal halide perovskite materials, with applications for solar cells or X-ray detectors. Moreover, understanding the dynamic evolution of the nanoparticles' structure during catalysis will enable one to boost the efficiency and stability of the catalytic process.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Kadu Ajinkya Anil

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Bimetallic MPt (M: Fe, Co, Ni) nanoparticles (NPs) displaying anisotropic morphologies are of great interest for the electrocatalytic oxygen reduction reaction (ORR). Unfortunately, MPt alloys in their native A1 phase rapidly degrade in acidic media and therefore severely restrict fuel cell applications. High temperature thermal annealing of CoPt and FePt NPs to achieve its chemically ordered L10 phase is crucially required to achieve an acid-stable catalyst and boost ORR activity to make fuel cells a financially viable technology. In CATOM, my goal is to establish a controlled route to thermally induce the L10 phase whilst protecting the catalyst morphology, achieving ORR performance and acid-stability within the same NP. I will gain the necessary insights to reach this ambitious goal by exploiting advanced electron microscopy (EM) techniques. Due to the complex NP morphologies, these investigations must be performed in 3D. I will therefore develop innovative quantitative electron tomography techniques to track atom-level dynamics and morphology evolution during the annealing process on the single particle level. Moreover, combining in situ gas cell annealing data with computational simulations will enable me to follow the 3D structure evolution of MPt alloys under realistic industrial conditions with atomic resolution. Finally, the direct comparison of A1 and L10 stability of faceted NPs during electrochemical cycling using a liquid cell holder will allow me to compare activation and degradation processes between the phases and to couple catalyst evolution with its ORR performance. These innovative experiments could not be obtained so far because of a lack of 3D characterization tools suitable to track NP evolution under realistic conditions. The outcome of my program will fundamentally advance in situ EM characterization techniques and direct future catalyst design to prepare highly active and acid-stable ORR catalysts critically needed for fuel cell development.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Jenkinson Kellie

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

One of the greatest global challenges is the minimization of greenhouse gas emissions. Finding a more eco-friendly alternative to the energy-intensive Haber-Bosch process is one way of tackling this problem. This project therefore focuses on the development of the nitrogen reduction reaction (NRR) under ambient conditions since it is more energy efficient. Unfortunately, current catalysts for this process have very low activities and selectivities. Here, we will design a new state-of-the-art catalyst: Fe-Au core-shell NPs on nitrogen-doped ordered mesoporous carbon (NOMC) supports. Both Fe and Au have shown great promise for NRR, but we believe that combining both elements in a core-shell will lead to synergy, in line with observations in other similar reactions. To improve stability as well as activity of the catalyst, the particles will be incorporated into an optimized mesoporous support. By combining advanced electron microscopy with electrochemical testing, links can be established between the 3D structure and the catalytic performance, allowing for a rational optimization of the catalyst. The impacts of the porous support, doping, particle loading, core-shell configuration and the structure of the interfaces on performance will be determined. Degradation mechanisms will also be studied to gain insight into catalyst deactivation and allow for improvement of the long-term stability. This research presents an important step towards making the NRR more industrially viable.

Researcher(s)

• Promoter: Breugelmans Tom
• Co-promoter: Bals Sara
• Fellow: Hoekx Saskia

Research team(s)

• Applied Electrochemistry & Catalysis (ELCAT)

Project type(s)

• Research Project

Abstract

The rapid progress in materials science that enables the design of materials down to the nanoscale also demands characterization techniques able to analyze the materials down to the same scale, such as transmission electron microscopy. As Belgium's foremost electron microscopy group, among the largest in the world, EMAT is continuously contributing to the development of TEM techniques, such as high-resolution imaging, diffraction, electron tomography, and spectroscopies, with an emphasis on quantification and reproducibility, as well as employing TEM methodology at the highest level to solve real-world materials science problems.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

For the University of Gent, high resolution HAADF-STEM images have been recorded in combination with STEM-EDX element mapping. The particles contained palladium and cobalt and did not have the expected shape.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Self-assembly of nanoparticles (NPs) offers a versatile platform for the design of novel materials with enhanced collective properties. A promising route to achieving tailored properties with NPs is to bring them together into superstructures called Supraparticles (SPs). The greatest potential for bringing forth diverse new properties comes from multicomponent SPs, in which multiple types of NPs are used in the SPs. I propose to use spherical confinement to first build SPs which I will then treat with cation exchange (CE), a powerful tool for synthesizing NPs with controlled structures. The goal is to establish a robust route to structuring multicomponent SPs in a controlled manner and enable the engineering of new SPs with optimal properties for applications ranging from catalysis to photovoltaics. A complete structural analysis of cation exchanged (CE-ed) SPs in 3D is essential as it will reveal the CE process in SPs. I will develop innovative quantitative 3D electron microscopy (EM) techniques to investigate the dynamics of the structural evolution of CE-ed SPs on the single NP level, providing insights into how to achieve optimal properties. Optimization of sample support and development of fast multimode electron tomography will make this possible by eliminate beam damage. Liquid tomography will allow me to fully understand the 3D structures of CE-ed SPs under realistic conditions. By combining in-situ heating and fast multimode electron tomography, I will decipher the mechanism of heat-induced intra- and inter- particle CE in SPs. My program will enable me to understand the interplay between NP shape, stacking and heating on the resulting SP structures. This program will be the start of a completely new research line in the fields of both colloidal science and 3D characterization. The outcome will boost the possibilities for the design and application of functional materials as well as push the limits of 3D EM techniques.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Wang Da

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Although recent advances in nanotechnology have provided an excellent platform to revolutionize the domain of health, the efficient and target delivery of many potent drugs in the body still remains an important challenge due to important drawbacks either from the drug (bioavailability, toxicity, etc.) and/or from the nanocarrier (biocompatibility, reproducibility, insufficient targeting). Consequently, there is currently a real demand for drug nanocarriers able to solve these matters for the different administration routes. HeatNMof project aims to develop smart multifunctional nanocarriers of challenging antitumoral drugs based on versatile highly porous biocompatible nanometric Metal Organic Frameworks, associated with exceptional drug payloads and controlled releases, and photo- and/or magnetic inorganic nanoparticles, providing both a specific control of reactions inside living entities (i.e. heating-triggered drug release) and additional properties such as imaging (magnetic resonance, thermal or optoacoustic imaging) and/ or hyperthermia therapy. The successful development of this project, involving academic and industrial partners, will contribute to the improvement of the highly societal relevant cancer therapy. This research objective is strongly related with the prime training/networking aim of HeatNMof: to train the next generation of materials scientists in a highly interdisciplinary and intersectorial research environment, such that they can soundly address upcoming challenges concerning nanomedicine, from the development, optimization and (physicochemical and biological) characterization of inorganic and hybrid materials, as well as their interaction with living entities, with a strong focus on drug delivery platforms based on nanomaterials. HeatNMof will train the next generation of material scientists with sound expertise in nanomedicine, highly needed to bring advanced materials as proposed from the bench to society.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

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.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: Hadermann Joke
• Co-promoter: Van Aert Sandra
• Co-promoter: Verbeeck Johan

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The ARCLATH project investigates how energy, in the form of molecular hydrogen, can be stored and transported in a crystal structure, so-called clathrates. This way, a new storage and transportation system is available so renewable energy can be used where and when it is needed.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

This project encompasses the structural characterisation of non-toxic quantum dots for advanced high intensity lighting applications, by using advanced transmission electron microscopy (TEM) techniques.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The properties of nanomaterials are essentially determined by their 3D structure. Electron tomography enables one to measure the morphology and composition of nanostructures in 3D, even at atomic resolution. Unfortunately, all these measurements are performed at room temperature and in ultra-high vacuum, which are conditions that are completely irrelevant for the use of nanoparticles in real applications! Moreover, nanoparticles often have ligands at their surface, which form the interface to the environment. These ligands are mostly neglected in imaging, although they strongly influence the growth, thermal stability and drive self-assembly. I will develop innovative and quantitative 3D characterisation tools, compatible with the fast changes of nanomaterials that occur in a realistic thermal and gaseous environment. To visualise surface ligands, I will combine direct electron detection with novel exit wave reconstruction techniques. Tracking the 3D structure of nanomaterials in a relevant environment is extremely challenging and ambitious. However, our preliminary experiments demonstrate the enormous impact. We will be able to perform a dynamic characterisation of shape changes of nanoparticles. This is important to improve thermal stability during drug delivery, sensing, data storage or hyperthermic cancer treatment. We will provide quantitative 3D measurements of the coordination numbers of the surface atoms of catalytic nanoparticles and follow the motion of individual atoms live during catalysis. By visualising surface ligands, we will understand their fundamental influence on particle shape and during self-assembly. This program will be the start of a completely new research line in the field of 3D imaging at the atomic scale. The outcome will certainly boost the design and performance of nanomaterials. This is not only of importance at a fundamental level, but is a prerequisite for the incorporation of nanomaterials in our future technology.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Self-assembly of nanoparticles (NPs) offers a versatile platform for the design of novel (meta) materials with enhanced collective properties that are distinct from the sum of the their components. A promising route to structure NPs over multiple length scales is to let the NPs assemble in spherical confinement to form Supraparticles (SPs). It is challenging to design multi-component SPs as the parameter space to achieve the optimum thermodynamics and kinetic effects is large. To tackle this challenge, we will apply cation exchange (CE) to already self-assembled SPs containing quantum dots (QDs). Multi-component SPs with different structures will be obtained, which is impossible to achieve by conventional synthetic routes. A complete analysis of resulting CE-ed SPs is essential because a thorough understanding of the structure-property connection of the SPs will enable more rational synthesis of novel structures with predefined properties. We will apply advanced Energy dispersive X-ray spectroscopy tomography to CE-ed SPs to extract positions, orientations, and elemental distributions of singe QDs in 3D. We will utilize advanced heating holder for electron tomography study heat-induced morphological and compositional- changes of the CE-ed SPs in 3D.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Wang Da

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

This project encompasses the development of a sample preparation protocol by focused ion beam - scanning electron microsopy (FIB-SEM) and (cryo-)ultramicrotomy. The coating of the particles is studied using scanning (SEM) and transmission (TEM) electron microscopy.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

PROCEED aims to develop a new hybrid perovskite material platform for next-generation light detectors, emitters and harvesters. Beyond photovoltaics, hybrid perovskites are materials with high potential for highly relevant applications such as X-ray detectors for medical diagnostic imaging and lasers for lighting and display. To make this potential effective, the chemical and structural flexibility of hybrid perovskites will be exploited to bring the material architecture to a next level of complexity with the introduction of extra functionalities. Implementation of novel hybrid perovskites of different composition and dimensionality (3D, 2D), structures (nanoplatelets, thin films, thick layers including nanocrystals), controlled morphology (crystallinity, uniformity), and their further integration in advanced device structures, will enable order-of-magnitude of improvement of the material stability together with a strong increase of the first figure-of-merit for each selected application – i.e. sensitivity for X-ray detectors, gain for laser, and power conversion efficiency for solar cells – beyond the level achievable by the respective current technologies, and with lower or similar production costs. The scope of this project requires synergy of multiple fields of science and engineering, such as chemistry, material science, processing, device fabrication and testing, demonstrators and reliability.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The design and synthesis of metal nanoparticles (NPs) with predefined size and shape remains a major challenge in materials science. Although the growth of Au NPs is mature, synthetic procedures have evolved largely empirically so far. Obtaining full control over the synthesis of Au NPs is of key importance toward their efficient applicability in e.g. photothermal therapy and plasmonic sensing. However, in order to optimize the synthesis protocols and obtain NPs with specific properties, a detailed quantitative structural characterization of the products during the different growth stages by advanced transmission electron microscopy (TEM) is needed. The aim of this project is to optimize TEM techniques and to develop novel three-dimensional (3D) characterization tools, adequate to elucidate different aspects in the growth of Au NPs that still remain unclear. These novel methodologies will allow me to characterize Au NPs at different growth stages, which will yield the necessary insights to gain control over both the growth of Au seeds as well as the Au NPs. A challenging and ambitious goal in this project will be to realize high throughput 3D studies to perform a statistically relevant analysis concerning the size and shape of NPs. This project will have a major impact on the synthesis of metal NPs. The outcome of our experiments will enable one to optimize the synthesis towards highly monodisperse NPs, which will lead to a more effective use in biomedical applications.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Bladt Eva

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Metal nanoparticles (NPs) are intriguing systems due to their efficient interactions with light stemming from localized surface plasmon resonances (LSPRs), a phenomenon which is exploited in many applications in fields ranging from physics to biology and medicine. In particular, anisotropic shapes are interesting because of strong electromagnetic field enhancements at corners and tips. Next to monometallic NPs, bimetallic NPs offer an additional way of tuning the functionality and plasmon resonance and are advantageous for applications such as photocatalysis. Understanding the delicate interplay between particle morphology, composition and optical properties is of utmost importance in optimizing particle design for the desired applications. While optical properties of metal NPs have been related to structure by using surface imaging techniques like scanning electron microscopy (SEM), a complete connection to the atomically resolved 3D structure has never been accomplished. Here, I propose to investigate the correlation of the full atomic morphology (including composition) and optical properties of (bi)metallic NPs by single-particle optical experiments and electron microscopy techniques such as atomically resolved electron tomography. I will furthermore study the correspondence and differences between electronically-excited and optically-excited plasmon modes. The key aspect of the proposed research is that the correlated measurements will be performed, for the first time, on the same particle allowing for a full understanding of how the morphology and composition of a metal NP is related to its optical properties.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Albrecht Wiebke

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Processes in energy applications and catalysis as well as biological processes become increasingly important as society's focus shifts to sustainable resources and technology. A thorough understanding of these processes needs their detailed observation at a nano or atomic scale. Transmission electron microscopy (TEM) is the optimal tool for this, but in its conventional form it requires the study object to be placed in ultrahigh vacuum, which makes most processes impossible. Using environmental TEM holders, the objects can be placed in a gas/vapour or liquid environment within the microscope, enabling the real time imaging, spectroscopic and diffraction analysis of the ongoing processes. This infrastructure will enable different research groups within the University of Antwerp to perform a wide range of novel research experiments involving the knowledge on processes and interactions, including among others the growth and evolution of biological matter, interaction of solids with gasses/vapours or liquid for catalysis, processes occurring upon charging and discharging rechargeable batteries, the nucleation and growth of nanoparticles and the detailed elucidation of intracellular pathways in biological processes relevant for future drug delivery therapies and treatments.

Researcher(s)

• Promoter: Hadermann Joke
• Co-promoter: Bals Sara
• Co-promoter: Breugelmans Tom
• Co-promoter: Meynen Vera
• Co-promoter: Sijbers Jan
• Co-promoter: Verbruggen Sammy

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

In the future, renewables will gain importance. Combining the use of CO2 as a feedstock along with the supply of renewable energy can compensate for fluctuations in energy production, while at the same time reducing CO2 emissions. In this PhD project, CO2 will be converted to CO through an electrochemical approach. At the moment, the electrochemical reduction of CO2 (ERC) is not yet industrially viable, mainly due to the lack of good electrocatalysts. In the past, different attempts have been made to improve the electrocatalytical activity, selectivity and stability while at the same time reducing the overall electrocatalyst cost. Over the last couple of years, core-shell nanoparticles (NPs) have emerged as promising candidates, reaching a high product selectivity, yet maintaining a low productivity. It is believed that the bimetallic enhancement effects, are behind the improved performance of these core-shell NPs when compared to the individual metals. Unfortunately, as they are still rather unexplored, a fundamental understanding of the core-shell interactions is still absent. This makes their characterization, being the major research objective of this PhD proposal, of the utmost importance to gain insight into the connection between morphology, structure, composition and the electrocatalytic properties and thus to further improve their ERC performance. A combined use of state-of-the-art electrochemistry and electron tomography will provide this in-depth understanding.

Researcher(s)

• Promoter: Breugelmans Tom
• Co-promoter: Bals Sara
• Fellow: Pacquets Lien

Research team(s)

• Applied Electrochemistry & Catalysis (ELCAT)

Project type(s)

• Research Project

Abstract

The overarching goal of MUMMERING is to create a research tool that encompasses the wealth of new 3D imaging modalities that are surging forward for applications in materials engineering, and to create a doctoral programme that trains 15 early stage researchers (ESRs) in this tool. This is urgently needed to prevent that massive amounts of valuable tomography data ends on a virtual scrapheap. The challenge of handling and analysing terabytes of3D data is already limiting the level of scientific insight that is extracted from many data sets. With faster acquisition times and multidimensional modali-ties, these challenges will soon scale to the petabyte regime. To meet this challenge, we will create an open access, open source platform that transparently and efficiently handles the complete workflow from data acquisition, over reconstruction and segmentation to physical modelling, including temporal models, i.e. 3D "movies". We consider it essential to reach this final step without compromising scientific standards if 3D imaging is to become a pervasive research tool in the visions for Industry 4.0. The 15 ESRs will be enrolled in an intensive network-wide doctoral training programme that covers all aspects of 3D imaging and will benefit from a varied track of intersectoral secondments that will challenge and broaden their scope and approach to research.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: De Beenhouwer Jan
• Co-promoter: Sijbers Jan

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

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.

Researcher(s)

• Promoter: Van Aert Sandra
• Co-promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

This project aims to develop a new quantum dot (QD) technology based on III-V elements, on the one hand to improve the color reproduction and reduce the energy consumption of screens, and on the other to broaden the application possibilities to light sources with a custom spectrum. For this, a switch will be made from a remote phosphor to an on-chip configuration, optimizing the performance, stability, cost and composition of the QDs.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The Francqui Foundation awards a Francqui Professorships at a Belgian Universities for a period of three years. The position is intended for young promising candidates, whose research is novel and exceptional and whose field of research belongs to an important and current scientific area. This position allows the mandate holder to fully dedicate themselves to their research.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

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

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

EUSMI will provide the community of European soft-matter researchers with an open-access infrastructure as a platform to support and extend their research, covering characterization, synthesis, and modeling. Where ESMI has set the standard for the past five years, EUSMI will significantly go beyond. EUSMI will enhance the European competitiveness in soft-matter research and innovation through the integration and the extension of the scope of existing specialized infrastructures. A full suite of coherent key infrastructures and the corresponding expertise from 15 toplevel institutions are combined within EUSMI, which will become accessible to a broad community of researchers operating at different levels of the value chain, including SMEs and applied research. Access is offered to infrastructures covering the full chain of functional soft-matter material research, ranging from advanced material characterization by a full suite of specialized experimental installations, including large-scale facilities, chemical synthesis of a full set of soft-matter materials, upscaling of laboratory synthesis, to modeling by high-performance supercomputing. The existing infrastructure will be continuously improved by JRA to allow users to conduct research always employing the most advanced techniques and methods.. In addition, an ambitious networking programme will ensure efficient dissemination and communication, as well as continued education of established researchers and training of an emerging generation of scientist. This approach will drive academic research and innovation in soft nanotechnology by providing a multidisciplinary set of essential research capabilities and expertise to guide users, developing the next generation of techniques and instruments to synthesize, characterize, and numerically simulate novel soft matter materials and contributing to the creation of a broad knowledge basis.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

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

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

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

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

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

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Electron tomography has evolved into a powerful technique to study the three-dimensional (3D) structure of functional nanomaterials. However, a major drawback is the total run time that is required to obtain the necessary 2D projection images, to align them and to compute the final 3D reconstruction. Since several hours are required to study a single nanoparticle, it is impossible to obtain a large set of measurements, required to connect the structure of functional nanomaterials to their properties. The latter is of crucial importance to observe the design of nanostructures with defined functionalities and the incorporation of such structures in future nanotechnology. Here, I will reduce the run time of electron tomography by a factor of 100 using a combination of novel acquisition procedures and dedicated 3D reconstruction algorithms. By applying highthroughput electron tomography, changes in the (surface) structure of catalytic nanoparticles or battery materials can be determined. In addition, the reduced acquisition time and electron dose will allow the 3D investigation of organic materials, zeolites or metalorganic frameworks. Since quasi real-time 3D imaging with the electron microscope will be possible within a few minutes, 3D experiments can be performed in a much more efficient manner to even monitor morphology changes as a function of heating. We therefore consider this project as the next (r)evolution in the field of electron tomography.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Vanrompay Hans

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Electron tomography has evolved into a state-of-the-art technique to investigate the 3 dimensional structure of nanomaterials, also at the atomic scale. However, new developments in the field of nanotechnology drive the need for even more advanced quantitative characterization techniques in 3 dimensions that can be applied to complex (hetero-)nanostructures. Here, we will focus on hetero-metallic particles with electrocatalytic applications and hard-soft core-shell structures that are of interest in the field of photocatalysis. Although catalytic hetero-nanoparticles yield improved properties in comparison to their parent compounds, the underlying reasons for this optimized behaviour are still debated. Therefore, innovative 3 dimensional electron microscopy techniques are required to understand the connection between the structure, composition and catalytic properties. The combination of advanced aberration corrected electron microscopy and novel 3 dimensional reconstruction algorithms is envisaged as a groundbreaking new approach to quantify the structure AND the composition for any given nanomaterial. By combining these innovative experiments with activity and stability tests under relevant conditions we will be able to solve fundamental questions, which are of importance for both electro- and photocatalysis. Through these insights, we aim to boost the activity of catalytic nanostructures and we envisage that the outcome of our project will have major impact. For example, a fundamental understanding of the plasmonic behaviour will greatly improve the photocatalytic performance in sunlight and therefore lies at the base of better air purification technology. Our project will also enable a founded selection of catalysts in order to proceed towards an industrially applicable reaction such as the reduction of CO2 or the Oxidation Reduction Reaction.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: Breugelmans Tom
• Co-promoter: Lenaerts Silvia

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Extensive research has recently been focused on the controllable synthesis of Lanthanide (Ln3+) doped nanomaterials with well-defined size and morphology because of their possible applications in lighting, displays, optoelectronics, solar energy, bio-imaging and photodynamic therapy. However, to optimize the properties and to incorporate these materials in actual devices, a fundamental understanding of the composition-structure-property relation is required. Transmission electron microscopy (TEM) is an excellent technique to investigate nanomaterials, but conventional TEM images are only two-dimensional (2D) projections of three-dimensional(3D) objects. In this project, a complete 3D characterization of Ln3+ doped nanomaterials down to the atomic scale will be provided through the combination of advanced TEM and novel 3D reconstruction algorithms. We will determine the 3D location and local environment of activators and sensitizers in host (core-shell) nanoparticles. Also, strain, intermixing and defects at the different interfaces of core-shell particles will be studied. Furthermore, the mobility of the activators and sensitizers at different temperatures will be monitored in 3D by in situ electron tomography. My project will have important impact since a thorough understanding of the composition-structure-property relation will enable the synthesis of nanomaterials with improved properties and the design of nanostructures with novel functionalities.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Zhang Yang

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Nowadays Li-ion batteries are the dominant technology for portable electronics and automotive applications. This project aims at further development of the new cathode materials for rechargeable batteries, including Li and Na batteries. It involves collaboration between EMAT and College de France (Paris). The group of prof. J.-M. Tarascon at College de France is specialized in synthesis and electrochemical characterization of a wide variety of novel cathode materials for rechargeable batteries. Their structural transformations upon charge/discharge processes cannot be always comprehensively understood using only bulk diffraction methods (X-ray/neutron), hence advanced transmission electron microscopy is often required. EMAT provides in depth characterization of the materials down to the atomic level using a variety TEM method, including electron diffraction methods and imaging techniques (HAADF- and ABF-STEM) that are often combined with chemical analysis using spectroscopy (STEM-EDX and STEM-EELS). As an outcome, the structure, composition and valence state of cathode materials can be directly visualized at different charge/discharge states, allowing for further development of new battery technologies.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Nano assemblies are two- or three-dimensional (3D) collections of nanoparticles. The properties of the assemblies are determined by the number of particles, their position, shape and chemical nature as well as the bonding between them. If we are able to determine these parameters in 3D, we will be able to provide the necessary input for predicting the properties and we can guide the synthesis and development of new assemblies or superstructures. The aim of this project is therefore to provide a complete 3D characterization of complex assemblies down to the atomic scale. We will reach this goal by combining advanced electron microscopy and novel 3D reconstruction algorithms. So far, 3D imaging of nano assemblies was performed for relatively small, model-like systems, consisting of spherical nanoparticles. Here, we will perform 3D measurements of larger and more complex assemblies consisting of anisotropic particles as well as binary systems in which the particles may have different compositions or sizes. Through aberration corrected TEM, we will also investigate the driving forces behind self assembly or oriented attachment at the atomic level. This project will have major impact for a broad range of applications such as drug delivery, magnetic recording or surface enhanced raman scattering. Once the connection between structure and properties is understood, the synthesis of complex assemblies can be optimized and the development of novel materials will be triggered.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Altantzis Thomas

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Electron tomography has evolved into a powerful technique to study the three-dimensional (3D) structure of nanomaterials. However, a major drawback is the total run time that is required to obtain the necessary 2D projection images, to align them and to compute the final 3D reconstruction. Since more than 3 hours are required to study a single nanoparticle in 3D, it is impossible to obtain a large set of measurements, required to connect the structure of nanomaterials to their properties. Also the 3D study of electron beam sensitive materials and realtime 3D studies are hampered. Here, I will reduce the run time of electron tomography by a factor of 100. I will reach this goal by combining novel acquisition procedures with dedicated 3D reconstruction algorithms. This will enable us to perform a whole new range of experiments. For example, by applying highthroughput electron tomography, changes in the (surface) structure of catalytic nanoparticles before and after cycling can be quantified. The reduced acquisition time and electron dose will allow the 3D investigation of zeolites or metalorganic frameworks. Since quasi real-time 3D imaging at the electron microscope will be possible with a temporal resolution of a few minutes, 3D experiments can be performed in a much more efficient manner and morphology changes as a function of heating can be investigated. We therefore consider this project as the next (r)evolution in the field of electron tomography.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: Goris Bart
• Fellow: Vanrompay Hans

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

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

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Over the past years, the complexity of nanosystems has increased tremendously. As a consequence, it is no longer sufficient to only characterise their structure and composition; electronic properties like valency and bonding must also be determined in parallel. This type of information can be retrieved using electron energy loss spectroscopy (EELS) at high energy resolution in a transmission electron microscope (TEM). Unfortunately, conventional TEM data remains a 2D projection of a 3D object. Therefore, the main goal of this project is to gain quantitative 3D information concerning the composition, structure and electronic properties of a wide range of nanomaterials by expanding EELS from 2D to 3D. The combination of advanced aberration corrected TEM and novel 3D reconstruction algorithms is envisioned as a ground-breaking new approach to quantify properties like valency, chemical composition, oxygen coordination, bond lengths, etc. in 3D. These experiments will clearly lead to unique insights that may even trigger the design and synthesis of nanomaterials with novel functionalities. We envisage that we will be able to understand the relationship between the 3D surface structure and catalytic functionalities and investigate the positioning of dopants in semiconductor nanocrystals and nanodiamonds. The combination of materials science, electron tomography and high resolution EELS provided here is unique and will enable us to answer fundamental questions in materials science.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: Batenburg Joost
• Co-promoter: Goris Bart
• Co-promoter: Turner Stuart

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Matter is a three-dimensional (3D) agglomeration of atoms. The properties of materials are determined by the positions of the atoms, their chemical nature and the bonding between them. If we can determine these parameters in 3D, we can provide the necessary input for predicting the properties and we can guide the development of new nanomaterials. The aim of this project is therefore to provide a complete 3D characterisation of complex heteronanosystems down to the atomic scale. The combination of advanced electron microscopy and novel 3D reconstruction algorithms is an innovative approach to quantify the position AND the colour (chemical nature and bonding) of each individual atom in 3D.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Bladt Eva

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

This project represents a research contract awarded by the University of Antwerp. The supervisor provides the Antwerp University research mentioned in the title of the project under the conditions stipulated by the university.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: Partoens Bart
• Fellow: Abakumov Artem
• Fellow: Neirinckx Alexander
• Fellow: Pfannmöller Martin
• Fellow: Pourbabak Saeid

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The NANO consortium of excellence represents the internationally renowned expertise in nanoscience at the University of Anwerp. It consists of three participating groups that are international leaders in their subfield: EMAT, CMT and PLASMANT. The consortium joins forces towards a uniform communication and collaboration in order to further strengthen the international position of the nanosciences at the University of Antwerp.

Researcher(s)

• Promoter: Verbeeck Johan
• Co-promoter: Bals Sara
• Co-promoter: Bogaerts Annemie
• Co-promoter: Partoens Bart
• Co-promoter: Schryvers Nick
• Co-promoter: Van Tendeloo Staf

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

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.

Researcher(s)

• Promoter: Van Aert Sandra
• Co-promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

During my PhD research, we developed and performed electron tomography experiments in order to measure the positions of the atoms in a nanostructure. However, the burning questions in the field of nanoscience can no longer be solved by only determining the atomic structure. Nowadays, it becomes crucial to measure the chemical nature and even the oxidation state of each individual atom in a nanostructure as well. Therefore, the aim of this project is to push the limits of electron tomography beyond the state-of-the-art and to provide a complete 3D quantitative chemical characterisation of complex hetero-nanosystems down to the atomic scale.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Goris Bart

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

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

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

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

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The goal of this program is to investigate the electronic properties of conventional, well-known 2-D semiconductors, which, however, obtain a rich Dirac band structure by their honeycomb nanogeometry. To reach this goal, we propose further efforts in the theoretical development, fabrication and electronic characterization of such systems.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

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

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

We propose a unique combination between in-situ evaluation of electrochemical deposition by nanocluster aggregation, state of the art atomic-scale characterization, and electrochemical modeling of the underlying processes. By means of this approach, we aim to provide a new alternative to obtain enhanced supported nanostructures by exploring nanocluster self-assembly during electrochemical deposition processes.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The overall goal of this project is to characterise and simulate the growth and stability of anisotropic Au and Au/Ag nanocrystals at the atomic scale. In order to reach this final objective, our intermediate technical goals are: • To experimentally determine the p osition and chemical nature of each individual atom in anisotropic Au and Au/Ag NP's. • To develop a reactive force field required for the atomistic simulations.

Researcher(s)

• Promoter: Neyts Erik
• Co-promoter: Bals Sara

Research team(s)

• Plasma Lab for Applications in Sustainability and Medicine - Antwerp (PLASMANT)

Project type(s)

• Research Project

Abstract

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

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The aim of this project is therefore to provide a complete 3D characterisation of complex hetero-nanosystems down to the atomic scale. The combination of advanced aberration corrected electron microscopy and novel 3D reconstruction algorithms is envisioned as a groundbreaking new approach to quantify the position AND the colour (chemical nature and bonding) of each individual atom in 3D for any given nanomaterial.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Matter is a three-dimensional (3D) agglomeration of atoms. The properties of materials are determined by the positions of the atoms, their chemical nature and the bonding between them. If we can determine these parameters in 3D, we can provide the necessary input for predicting the properties and we can guide the development of new nanomaterials. The aim of this project is therefore to provide a complete 3D characterisation of complex heteronanosystems down to the atomic scale. The combination of advanced electron microscopy and novel 3D reconstruction algorithms is an innovative approach to quantify the position AND the colour (chemical nature and bonding) of each individual atom in 3D.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Bladt Eva

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

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

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: Verbeeck Johan

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

SUNFLOWER is a collaborative research project of 17 partner institutions from science and industry. Its goal is the development of highly efficient, long-lasting, cheap and environmentally friendly printed organic photovoltaics. TEM will be used to charactrize degradation.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

We aim to characterize strain at the atomic scale near interfaces in (core-shell) nanoparticles. Such interfaces have a large impact on the properties of the structures and it is therefore crucial to gain a thorough understanding on the atomic structure in order to optimize these core shell particles towards possible optical applications. Moreover, we will investigate the presence of lattice strain near atomic defects such as dislocations or vacancies based on the atomic resolution electron tomography technique that was developed in the first part of the project.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Goris Bart

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

"Soft matter" is anything from a well-defined term. It is used to represent a broad class of materials including colloids, polymers, biological specimens and biomaterials. Although the use of such materials becomes increasingly important in nanotechnology, a successful implementation can only be reached through a thorough structural investigation at the nanolevel. Electron microscopy is the most widely used technique to study inorganic (nano)materials, even at the atomic scale. Such investigations however, are far from straightforward when soft matter is considered. Therefore this application aims at an environmental scanning electron microscope as well as a cryo ultramicrotome.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: Adriaensen Dirk
• Co-promoter: De Wael Karolien

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

This is a fundamental research project financed by the Research Foundation - Flanders (FWO). The project was subsidized after selection by the FWO-expert panel. For the successful realization of the next generation of nano-scale devices, the understanding of contact formation needs to be improved. Both the aggressive downscaling of traditional silicon technology, as well as the introduction of high mobility or large bandgap semiconductors (Ge, InGaAs, GaN, SiC), move contact formation into areas of solid state physics which are relatively unexplored. This project aims at a fundamental study of metal/semiconductor contacts at nanoscale dimensions.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The relation between structure and activity will be optimized for two classes of nanoporous materials: TiO2 nanotubes combined with Ag nanoparticles and Periodic Mesoporous Organosilica's. This will be done based on a multidisciplinary approach combining advanced 3-dimensional imaging with modern computational methods at an atomic scale. This will lead to a more direct optimization of the synthesis and activity of the nanoporous materials in comparison to the classic trial-and-error procedures.

Researcher(s)

• Promoter: Cool Pegie
• Co-promoter: Bals Sara
• Co-promoter: Batenburg Joost
• Co-promoter: Partoens Bart

Research team(s)

• Laboratory of adsorption and catalysis (LADCA)

Project type(s)

• Research Project

Abstract

NaPoS will focus on structural hybrid materials, more specifically on steel fibres or plates/sheets combined with polymers. The aim of the NaPoS research project, within the NanoForce SIBO program is to develop a scientific base to optimise the interaction between steel and polymers.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Structural and chemical characterization of aCNTb's on the atomic level as well as micro-scale will be investigated. Mechanical deformation of aCNTb's as well as aCNTb-based composites will be studied by means of in-situ characterization techniques. Develop a novel process for the synthesis and extraction of CNTs to aCNTb's in a single continuous process to obtain high stiffness and high toughness aCNTb's.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Knowledge on the 3 dimensional structure and composition of nanomaterials at the atomic scale is indispensable when one wants to understand the physical properties of nanostructures in comparison to their bulk counterparts. Several groups have therefore dedicated a lot of effort towards reaching atomic resolution in 3 dimensions by transmission electron microscopy (TEM), but most studies remain theoretical or present experimental results which are not yet convincing. In most of these studies one specific TEM technique is selected, but in my project, I propose to combine different state-of-the-art TEM techniques and to exploit the information they can deliver as much as possible. Such a hybrid approach defines a complete new path on the route towards atomic resolution tomography. I will combine a limited number of in zone-axis projections, yielding atomic resolution, with a full tilt series of projections acquired at lower magnifications. Furthermore, I will expand the so-called "depth sectioning technique" to push its resolution to the sub nanometer level. Beam damage will be kept at a strict minimum by operating an aberration corrected TEM at low acceleration voltage. This will allow me to study the 3D atomic structure of core-shell particles and interfaces present in assemblies of nanocrystals.

Researcher(s)

• Promoter: Bals Sara
• Fellow: Goris Bart

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Magnetic Resonance imaging plays a crucial role in stem cell research in order to investigate whether administered stem cells are able to migrate to the target organ, locally survive, differentiate and contribute to regenerated tissue. However, knowledge regarding the interaction of MRI contrast agents with (sub)cellular structures is lacking. In this project, we will use advanced TEM techniques to investigate different MRI contrast agents and loading techniques for neural stem cells.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: Ponsaerts Peter
• Co-promoter: Van Der Linden Annemie

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The main goal of this project is to understand the formation of metallic nanowires mediated by protein-derived biomolecular templates in such a way that the properties of the fabricated nanowires, including diameter and coverage, become controllable. This goal will be achieved by investigating the effect of different process parameters on the morphology of the nanowires. The structural information which is obtained by TEM and AFM will be combined with the outcome of the modeling studies.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: Milosevic Milorad

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The aim of this project is threefold. First, we aim at the generation of supported metal and alloy particles on different substrates by surface mediated chemical or electrochemical deposition. Second, we concentrate on the modification of these particles by changing their surface properties. In view of the complexity surrounding the investigation of the structure and electronic properties of systems with nanoscale dimensions, a variety of complementary experimental methods will be used. The unification of those techniques into a methodologically homogeneous approach is the third goal of the project.

Researcher(s)

• Promoter: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

The main goal of this project is to develop discrete tomography for electron microscopy. As a starting point for the development of new reconstruction algorithms, the DART (Discrete Algebraic Reconstruction Technique) algorithm will be used. DART is an iterative algebraic reconstruction algorithm that is currently being developed at VISION LAB. It alternates between steps of the SIRT algorithm from continuous tomography and certian descretization steps. Within the SIRT iterations, subsets of the pixels are fixed at one of the constant grey levels, creating a new system of equations with fewer unknown than the original system.

Researcher(s)

• Promoter: Bals Sara
• Co-promoter: Batenburg Joost
• Co-promoter: Sijbers Jan

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

During the last 20 years, a strong evolution can be observed in the demands that are imposed on microscopic and nanoscopic characterization methods. Newly developed materials are becoming increasingly complex with respect to their chemical composition and structure on the micro/nanoscopic level. This has been the driving force for recent and spectacular developments in the world of transmission electron microscopy (TEM). Besides the race towards a better resolution using aberration corrected microscopes, directly interpretable results are obtained using advanced techniques such as exit wave reconstruction and high angular annular dark field scanning transmission electron microscopy (HAADF-STEM). However, these techniques have often been used to obtain results in well known systems such as Si and Au. Most technological applications however require much more complex materials. Apparently, applying the techniques mentioned above in order to solve problems relevant for solid state physics is not straightforward. This challenge forms the goal of our project.

Researcher(s)

• Promoter: Van Tendeloo Staf
• Fellow: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Ceramic thin films have attracted great interest since they exhibit a rich spectrum of physical properties (e.g. ferromagnetism, colossal magnetoresistance and superconductivity). The nature of these properties is determined by very small characteristic length scales. Up till now, high-resolution transmission electron microscopy (HRTEM) was considered as the standard technique to study the atomic structure of thin films. However, the analysis of HRTEM images is hampered by aberrations of the electromagnetic lens system. Another disadvantage of "classical" microscopy is the fact that only intensity (=(amplitude)2), can be recorded and therefore, an essential part of the electron wave, being the phase, is lost. Different techniques have been developed to solve the above-mentioned problems and two of them will be used in this project: the "focus variation" technique and "off-axis electron holography". Up till now, these methodes were only used in experiments in which the structure of the materials was already know. Therefore, the challenge of this project is to use quantitative HRTEM in the study of nanosystems and systems in which local (tiny) structural changes influence their properties. Atom positions near interfaces and defects may deviate from their ideal positions. However, these small changes can have a large influence on the physical properties of the materials. The intention of this project is to determine atom positions (or strain) near planar discontinuities (substrate-film interfaces, crystal defects, ...) in nanostructured materials with a precision of 5-10 pm. In practise, the experiments will primary use superconducting (La-Sr)CuO4 thin films on a LaSrAlO4 substrate and (La-Sr)MnO3 CMR materials, deposited on different substrates.

Researcher(s)

• Promoter: Van Tendeloo Staf
• Fellow: Bals Sara

Research team(s)

• Electron microscopy for materials research (EMAT)

Project type(s)

• Research Project

Abstract

Within this project we will investigate grainboundaries and interfaces in superconducting thin films and tapes using high resolution transmission electron microscopy. This will lead to an optimization of the physical properties of these systems.

Researcher(s)

• Promoter: Van Tendeloo Staf
• Fellow: Bals Sara

Research team(s)

Project type(s)

• Research Project

Abstract

Within this project we will investigate grainboundaries and interfaces in superconducting thin films and tapes using high resolution transmission electron microscopy. This will lead to an optimization of the physical properties of these systems.

Researcher(s)

• Promoter: Van Tendeloo Staf
• Fellow: Bals Sara

Research team(s)

Project type(s)

• Research Project