Friday Lectures

by Ihtasham Ul Haq

Investigation of the nanoscale plasticity/damage mechanisms in Earth mantle silicates by transmission electron microscopy

Practical

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

Ihtasham Ul Haq1, Patrick Cordier2,3, Dominique Schryvers1, Hosni Idrissi1,4
1EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp, Belgium
2Univ. Lille, CNRS, INRAE, Centrale Lille, UMR 8207 - UMET - Unité Matériaux et Transformations, F-59000 Lille, France
3Institut Universitaire de France, F-75005 Paris, France
4Institute of Mechanics, Materials and Civil Engineering (IMMC), UCLouvain, B-1348, Louvain‐la‐Neuve, Belgium

Abstract

Olivine is the most abundant (> 60 % in volume) and weakest phase in the Earth’s upper mantle of which it controls the rheology. The lack of slip systems in this crystal leads to the activation of other intergranular deformation mechanisms to accommodate a general strain. Our study focuses on the grain boundary sliding mechanism, based on grain boundary amorphization which was reported recently (1). For this elementary deformation mechanism, quantitative investigations are carried out on a bi-crystal forsterite tensile specimen by in-situ TEM test with a Push-to-Pull device. This work uses synthetic forsterite (the magnesium-rich end member of the olivine solid solution) samples.  We show that specimens deform exclusively by grain boundary sliding. Detailed microstructural investigation shows direct evidence of stress-induced amorphization in the sliding grain boundaries. In addition, the localization of the small strain onset of the grain boundary sliding mechanism was probed with the help of the in-situ TEM digital image correlation technique. Moreover, the effect of the iron addition (Fayalite; iron-rich end member of olivine solid solution) has been investigated. It is observed that the iron makes the sliding of the grain boundary more difficult.

After successfully adopting the nanomechanical technique on the olivine, it is extended to study the mechanical properties of phyllosilicates. Talc mineral (phyllosilicate) is the alteration product of stress-induced dolomite and silica-rich fluids in fault zones, where it can escalate into a long network that influences crustal mechanics. The formation of the interconnected network in the host rock contributes to the weakening of the fault through the frictional slip mechanism (2). One of the most intriguing aspects of talc is its mechanical anisotropy, which refers to the variation of mechanical properties in different crystal orientations (3). Taking advantage of the in-situ nanomechanical testing, the response of the talc has been determined between different crystallographic directions. This will bridge the gap between materials science and geoscience, contributing to a deep understanding of rock mechanisms, and frictional behavior in geological settings.

1.        Samae V, Cordier P, Demouchy S, Bollinger C, Gasc J, Koizumi S, Mussi, A., Schryvers, D., & Idrissi, H. (2021). Stress-induced amorphization triggers deformation in the lithospheric mantle. Nature. 2021 Mar 4;591(7848):82–6.

2.        Viti C, Collettini C. Growth and deformation mechanisms of talc along a natural fault: A micro/ nanostructural investigation. Contributions to Mineralogy and Petrology. 2009;158(4):529–42.

3.        Gatta GD, Merlini M, Valdrè G, Liermann HP, Nénert G, Rothkirch A, et al. On the crystal structure and compressional behavior of talc: A mineral of interest in petrology and material science. Phys Chem Miner. 2013 Feb 1;40(2):145–56. 

by Saffiyye Kavak

Exploring Metal-Organic Frameworks (MOFs) Through High-Resolution TEM Imaging with Low-Dose Techniques

Practical

• location (online link) by invitation only
• Time: 10:30

Abstract

Metal-organic frameworks (MOFs) possess remarkable features, including high porosity, crystallinity, and customizable chemistry. This flexibility enables precise control over their morphologies, the incorporation of additional elements, and the introduction of defects. Their unlimited combinations of metal ions and organic linkers render them versatile materials applicable in diverse fields, such as catalysis,1 controlled drug delivery,2,3 energy storage,4 gas storage, and separation5,6. Gaining insights into local features of MOFs, including defects and incorporated elements, is very important to fundamentally understand these materials.

Transmission electron microscopy (TEM) is an excellent technique to achieve local characterization. However, the extreme sensitivity of MOFs to the electron beam represents a significant challenge. Radiolysis emerges as the main mechanism behind beam-induced damage in MOFs,7,8 leading to structural alterations and loss of crystallinity.

In this lecture, I will first delve into the beam stability of MOFs, quantifying their critical dose (Dc) and half-life time dose (D1/2) to understand their structural changes over accumulated electron dose. Furthermore, the impact of working conditions, such as gaseous mixtures, on MOF stability will be also presented.

High-resolution investigation of various MOFs performed by respecting their D1/2 will be presented. To achieve this, we employ low-dose imaging techniques. These include integrated differential phase contrast (iDPC) by using segmented DF4 detector, and 4D-STEM datasets acquired using pixelated Timepix39 detector, from which the signal is reconstructed by using real-time integrated center of mass (riCOM)10 algorithm. These methods enable us to study pristine and pure-phase MOFs, as well as MOF-MOF interfaces, where two similarly structured MOFs are intergrown. Additionally, recent electron tomography results from MOFs will be discussed, on the way to achieve high-resolution 3D imaging while minimizing damage. 

1.         Yang, D.; Gates, B. C. Catalysis by Metal Organic Frameworks: Perspective and Suggestions for Future Research. ACS Catal 2019, 9, 1779–1798.

2.        Zheng, H.; Zhang, Y.; Liu, L.; Wan, W.; Guo, P.; Nyström, A. M.; Zou, X. One-Pot Synthesis of Metal–Organic Frameworks with Encapsulated Target Molecules and Their Applications for Controlled Drug Delivery. J Am Chem Soc 2016, 138, 962–968.

3.        Picchi, D. F.; Biglione, C.; Horcajada, P. Nanocomposites Based on Magnetic Nanoparticles and Metal–Organic Frameworks for Therapy, Diagnosis, and Theragnostics. ACS Nanoscience Au 2023.

4.        Baumann, A. E.; Burns, D. A.; Liu, B.; Thoi, V. S. Metal-Organic Framework Functionalization and Design Strategies for Advanced Electrochemical Energy Storage Devices. Commun Chem 2019, 2, 86.

5.        Li, B.; Wen, H.-M.; Zhou, W.; Chen, B. Porous Metal–Organic Frameworks for Gas Storage and Separation: What, How, and Why? J Phys Chem Lett 2014, 5, 3468–3479.

6.        Li, H.; Wang, K.; Sun, Y.; Lollar, C. T.; Li, J.; Zhou, H.-C. Recent Advances in Gas Storage and Separation Using Metal–Organic Frameworks. Materials Today2018, 21, 108–121.

7.        Liu, L.; Zhang, D.; Zhu, Y.; Han, Y. Bulk and Local Structures of Metal–Organic Frameworks Unravelled by High-Resolution Electron Microscopy. Commun Chem2020, 3, 99.

8.        Ghosh, S.; Kumar, P.; Conrad, S.; Tsapatsis, M.; Mkhoyan, K. A. Electron-Beam-Damage in Metal Organic Frameworks in the TEM. Microscopy and Microanalysis 2019, 25, 1704–1705.

9.        Poikela, T.; Plosila, J.; Westerlund, T.; Campbell, M.; Gaspari, M. De; Llopart, X.; Gromov, V.; Kluit, R.; van Beuzekom, M.; Zappon, F.; Zivkovic, V.; Brezina, C.; Desch, K.; Fu, Y.; Kruth, A. Timepix3: A 65K Channel Hybrid Pixel Readout Chip with Simultaneous ToA/ToT and Sparse Readout. Journal of Instrumentation 2014, 9, C05013.

10.       Yu, C.-P.; Friedrich, T.; Jannis, D.; Van Aert, S.; Verbeeck, J. Real-Time Integration Center of Mass (RiCOM) Reconstruction for 4D STEM. Microscopy and Microanalysis 2022, 28, 1526–1537.

by Daesung Park (Dept of Energy Conversion and Storage, Functional Oxides, DTU , Copenhagen, Denmark)

Emergence of Piezoelectric and Pyroelectric Effects in Centrosymmetric Oxides by Controlling Ionic Defects

Practical

• location (online link) by invitation only
• Time: 10:30

Abstract

For next generation energy and electronic device applications, piezoelectric, pyroelectric, and ferroelectric materials are of high technological and industrial importance due to their energy conversion properties. Piezoelectricity converts mechanical energy to electrical energy, and vice versa, while pyroelectricity utilizes temporal changes in temperature-dependent spontaneous polarization for electricity generation. These phenomena have been extensively investigated over the centuries for their applications such as actuation, sensing, energy harvesting, and thermal management. However, within the current research paradigm, the choice of piezoelectric and pyroelectric materials is limited to those with non-centrosymmetric crystal structures. Besides the existing strategies for material design and engineering, controlling ionic defects such as vacancies can be an effective approach for modifying material crystal symmetry/dimension, enabling the generation of new functional properties including emergent piezoelectricity and pyroelectricity. In this talk, I will introduce how the fundamental crystal limitation can be circumvented by breaking the lattice symmetry of intrinsically centrosymmetric oxide materials [e.g., Gd-doped CeO2-x (CGO) and undoped SrTiO3] to induce emergent electromechanical coupling and pyroelectricity. These can be achieved by creating, controlling, and stabilizing atomic charge defects through different approaches, for example, applying thin film growth techniques and electric field control. Such defect engineering can remarkably lead to generating sustainable and highly efficient piezoelectric and pyroelectric effects in the engineered CGO and STO thin films, which are comparable with or even beyond those of current high-performance piezoelectric and pyroelectric materials. The unprecedented defect-mediated phase separation and domain-like structure formation observed in these film materials will be also discussed. 

By Sepideh Rahimi

In-situ TEM on lithium-sulfur battery cathode materials

Practical

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

Abstract

Sulfur is known for its high specific capacity (1675 mAh/g) as the cathode material in Lithium-sulfur batteries (LSBs). LSBs have attracted a lot of attention among industrial and scientific parties due to the light weight of the active material, low-cost ingredients, and being more environmentally friendly than conventional lithium-ion batteries (LIBs). In LSBs, the limitation is the shuttling effect where different polysulfides (Sn with n=1,2,…,8) are (re)produced during the oxidation reaction of sulfur with lithium, and dissolve in the electrolyte. As a consequence, sulfur will deposit on the lithium anode and cause capacity loss since the cathode material is consumed in each cycle. Therefore, the evolution of the sulfur structure during cycling is important for its lifetime capacity. In literature, many studies are trying to prevent this effect, but details about the crystal structure of different species during the shuttling have remained unclear. This is due to the small particle size of the newly generated solid species during the reaction that in-situ XRD cannot accurately follow. Now with the development of the in-situ TEM holders, it is possible to study the Li-S battery system with electron diffraction. In this work, we tried to investigate the use of pure sulfur and Li2S as the starting solid materials for the charge and discharge procedures, respectively. Also, a parallel investigation of the Li electrochemical deposition on the counter electrode was carried out to be used as the negative electrode for the battery cycling reaction afterward.

By Gizem Şentürk

Unscrambling complex heterogeneous nanostructures by using quantitative 4D STEM

Practical

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

Abstract

To understand the structure-property relationship of nanostructures, reliably quantifying parameters, such as the number and types of atoms, is important. Advanced statistics- and simulations-based methodologies have made it possible to count the number of atoms for monotype crystalline nanostructures from a single ADF STEM image [1,2]. For this purpose, the so-called scattering cross-sections (SCS), corresponding to the total scattered intensity for each atomic column, perform as a successful measurement [3]. However, extending this technique to heterogeneous materials consisting of multiple types of elements is complicated since the SCS measurements of mixed-type atomic columns with varying thicknesses and chemical composition overlap in the presence of noise.

To characterise these types of nanostructures employing traditional methodologies, one often needs prior information on shape or size [4] which is not always available. 

To perform characterisation by avoiding prior knowledge, we offer to use a combination of multiple ADF STEM images obtained from non-overlapping annular detector collection regions, revealing independent information concerning thickness and composition of atomic columns. For this purpose, 4D STEM technique is beneficial since it provides a flexibility to create multiple 2D STEM images with arbitrary annular detector settings [5]. 

In this study, we explore the extension of both statistics- and simulations-based methodologies for such a multimode ADF STEM imaging approach and achieve atom counting of each type of element in heterogeneous nanostructures [9, 10]. Moreover, strategies that would reveal these unknown atom counts with the highest attainable accuracy and precision are investigated by deriving optimal statistical experimental settings [6,7,8]. This talk will show the benefits of using additional signals resulting from multiple ADF STEM images and ultimately from a 4D dataset especially when characterising multi-element nanostructures, offering a dose-efficient alternative when investigating beam sensitive materials. 

[1] A. De Backer et al, Nanoscale 9 (2017) 8791-8798.

[2] T. Altantzis et al, Nanoletters 19 (2019) 477-481.

[3] A. De Backer et al, Ultramicroscopy 134 (2013) 23-33.

[4] K.H.W van den Bos et al, Phys. Rev. Lett.116 (2016) 246101.

[5] N. Shibata et al, J. Electron Microsc. 59 (2010) 473.

[6] J. Gonnissen et al., Appl. Phys. Lett. 105 (2014) 063116.

[7] A. De Backer et al., Ultramicroscopy 151 (2015) 46.

[8] D.G. Senturk et al., Ultramicroscopy, 242 (2022) 113626.

[9] D.G. Senturk et al., Ultramicroscopy, 255 (2024) 113859.

[10] D.G. Senturk et al., Ultramicroscopy, 259 (2024) 113941.

By Amirhossein Hajizadeh

In-situ microscopy of energy-related materials in gas and liquid environments. Challenges and progress

Practical

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

Abstract

The phase transformation of electroactive materials under electrical load in several applications such as lithium-ion batteries, electrocatalysts, and solid-oxide fuel cells reveals the mechanism of the electrochemical process. In addition, it provides the answer to the degradation of the materials at the atomic scale during the electrochemical process.

Nowadays, 3D electron diffraction (3D ED) is a powerful method for studying the crystal structure of materials. The intensive electron interaction in this method with the specimen revealed new features about the structure of different types of materials which were indistinguishable by other methods like X-ray or Neutron diffraction.

In-situ holders for transmission electron microscopy (TEM) facilitate studying the phase transformation for different applications while heating or during the electrochemical measurements under the desired atmosphere. However, the special configuration of these holders produces new challenges in researching different materials.

In this lecture, my challenges of in-situ studying different materials in liquid and gas environments and the methods to overcome these difficulties will be discussed. Furthermore, the results obtained for different materials will be presented.

By Nikita Denisov

Development of an Automated Electron Diffractometer for high throughput identification of nanocrystalline materials (Automat-ED)

Practical

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

Abstract

Diffraction is a reliable tool to obtain information about the crystalline structure. The most used method for performing diffraction analysis is X-ray diffraction (XRD). Alongside XRD, diffraction in a transmission electron microscope (TEM) has also been commonly used. Electron diffraction has several advantages over XRD. Electrons provide more information for the same beam damage and the same volume of material; they are more sensitive to lighter atoms in the presence of heavy ones; they can be focused to probes of sub-Angstrom size. This means that when particles to be studied get smaller, the benefit of electron diffraction as compared to X-ray diffraction becomes higher. Especially with the trend to an ever-decreasing size of nanoparticles also in an industrial context, the method of electron diffraction is becoming more and more attractive.

Such smaller nanoparticles could also shift the required acceleration voltage used for electron diffraction and even relatively simple SEM tools start to form an interesting platform for electron diffraction. Indeed, the form factor of an SEM instrument provides more flexibility in terms of sample manipulation and offers more space for alternative experimental setups. Also, SEM instruments lend themselves very well for automation through full software control over the instrument, take up far less lab space, and are considerably more affordable than TEM instruments.

CCD cameras were and still are commonly used in TEM diffraction studies even though they impose several limitations and can show artifacts that are difficult to correct for. Nowadays Direct Electron Detectors (DED) are becoming available showing great potential for electron diffraction, especially with the hybrid pixel configuration. These new detectors can provide single electron detection capabilities with counting noise remaining the only source of error.

A lower acceleration voltage as compared to conventional TEM leads to a decrease of maximal sample thickness. The combination of using quasi-ideal detectors, rapid automation and smart scanning strategies helps to push the limit of transmission in SEM, fight beam damage and sample contamination. By merging scanning electron microscope, direct electron detector and automatic control Automat-ED project aims to create a versatile tool for a high-resolution electron diffraction structure investigation requiring minimum user input.

During this talk, I will characterize DED detector for diffraction studies at acceleration voltages in the SEM range, discuss the current prototype setup and present data acquisition / processing approaches that were developed working on project.

By Evgenii Vlasov

Exploiting secondary electrons in transmission electron microscopy for 3D characterization of nanoparticle morphologies

Practical

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

Abstract

In past decades, electron tomography (ET) has become a powerful tool for determining the three-dimensional (3D) structure of nanomaterials in transmission electron microscopy (TEM). ET enables 3D characterization of a variety of nanomaterials in different fields, such as life sciences, chemistry, solid-state physics, and materials science down to atomic resolution. However, the acquisition of a conventional tilt series for ET is a time-consuming process and thus cannot capture fast transformations of materials in realistic conditions. Moreover, only a limited number of nanoparticles (NPs) can be investigated, hampering a general understanding of the average properties of the material. Even though current state-of-the-art approaches allow for significant acceleration of the acquisition process, ET in situ heating experiments remain challenging, since the specimen needs to be quenched to room temperature to avoid changes of the NPs during the acquisition. Therefore, alternative characterization techniques that allow for high-resolution characterization of the surface structure without the need to acquire a full tilt series in ET are required which would enable a more time-efficient investigation with better statistical value and more representative in situ experiments.

In this talk, I will discuss an alternative technique for the characterization of the morphology of NPs to improve the throughput and temporal resolution of ET. The proposed technique exploits surface-sensitive secondary electron (SE) imaging employed using a modification of electron beam-induced current (EBIC) setup [1]. The first part of my presentation is concerned with the development of SEEBIC as an alternative way for the visualization of the 3D structure of NPs. The time- and dose efficiency of SEEBIC are tested in comparison with ET and superior spatial resolution is shown compared to SEM. Finally, contrast artefacts arising in SEEBIC images are described, and their origin is discussed [2]. 

In the second part of my presentation, I will discuss real applications of the developed technique and introduce a high-throughput methodology that combines images acquired by SEEBIC with quantitative image analysis to retrieve information about the helicity of Au nanorods. I will show that SEEBIC imaging overcomes the limitation of ET providing a general understanding of the connection between structure and chiroptical properties.

In the final part of my talk, I will present the overall outcome of my PhD work, and provide a perspective on the future application of SEEBIC for the characterization of the 3D structure of nanomaterials.

References:

1. W. Hubbard, et al, Phys Rev Appl 2018, 10, 044066.
2. E. Vlasov et al, ACS Mater Lett 2023, 5, 1916.

By Maciej Pasniewski

Influence of Instrumental Parameters of FIB-SEM on Polyolefins

Practical

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

Abstract

Polyolefins such as polyethylene (PE) and polypropylene (PP) are the most used polymers worldwide. They play a crucial role in everyday applications such as food packaging, agriculture, hygiene, automotive applications… The development of new materials with improved properties is guided by an in-depth understanding of the microstructure and compositional distribution, enabled by a suite of microscopy techniques, including electron (SEM, TEM) and atomic force microscopies (AFM), and derived combined methods like AFM-IR (infrared spectroscopy).

The versatility of the FIB-SEM as both an in situ analysis tool and a sample preparation tool makes it very useful for multi-scale analysis. However, interaction of matter with ions brings concerns regarding the nature of the newly created surfaces and how representative they are of the bulk phase, especially for such beam-sensitive materials as polyolefins. In general, fundamental effects of ion beams on such materials have not been investigated in-depth yet. This work tries to create a better understanding of these effects and how they could be managed.

This presentation will focus on the influence of instrumental parameters of gallium and gas plasma (Xe, O2) FIBs on Low Density Polyethylene (LDPE) and PP. The studied effects include implantation depth of ions into bulk matter and molecular damage caused by the impact of the FIB. The analyses were performed with Time-of-Flight – Secondary Ion Mass Spectrometry (ToF-SIMS) depth profiling. Depth calibration with optical profilometry is ongoing. Final analyses including study of FIB’ed surfaces with AFM are ongoing.

By Tiago Rebelo

Characterization and quantification of chirality in nanoparticles

Practical

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

Abstract

Chirality, or the inability of superimposing an object and its mirror reflection, is a symmetry property that has an enormous impact in different fields The interaction of two enantiomers the object and its mirror reflection ) with other compounds or external stimuli can not only shed light on fundamental phenomena and mechanisms but also find applicability in many areas from chemistry to physics [ 1], drug design, biology and medicine [2]. 

However, control over chirality is still limited and many aspects are not fully understood, such as how chiral compounds crystallize from 2D to 3D or how systems opt for one enantiomer over another [ 3]. Of particular interest are chiral nanoparticles (NPs), which despite the huge potential for applications, are still elu sive in terms of achieving precise control over their shape . Furthermore, there is a lack of techniques to quantify objectively how chiral a NP is, which would provide in valuable information on their design. 

In this presentation, I will show how HAADF STEM can be used to investigate chirality at the atomic scale . Additionally , when combined with electron tomography, it enables the evaluation of the shape of chiral NPs . I will also present quantification results obtained using an existing methodology [4] and explore its limitations, along with suggestions for possible next steps in this effort. 

[1] Ma, W., Xu, L., de Moura, A. F., Wu, X., Kuang, H., Xu, C., & Kotov, N. A. (2017). Chiral inorganic nanostructures. Chemical Reviews, 117(12), 8041 8093.
[2] Volpatti, L. R., Vendruscolo, M., Dobson, C. M., & Knowles, T. P. (2013). A clear view of polymorphism, twist, and chirality in amyloid fibril formation. ACS nano , 7 (12), 10443 10448
[3] Kondepudi, D. K., & Asakura, K. (2001). Chiral autocatalysis, spontaneous symmetry breaking, and stochastic behavior. Accounts of chemical research , 34 (12), 946 954.
[4] Heyvaert, W., Pedrazo Tardajos, A., Kadu, A., Claes, N., González Rubio, G., Liz Marzán, L. M., Albrecht , W. & Bals, S. (2022). Quantification of the helical morphology of chiral gold nanorods. ACS materials letters, 4(4), 642-649.

By Noa Olluyn

Physicochemical characterization methods for advancing NAM based approaches for risk assessment of nanomaterials applied in the food chain applied on synthetic amorphous silica, pearlescent pigments, and iron oxide impurities. 

Practical

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

Abstract

Applications of nanomaterials (NMs) in the food sector are increasing rapidly e.g. as novel foods, food/feed additives and flavourings, nutrients, food contact materials, and nano-formulated pesticides. The European Food Safety Authority (EFSA) identified nanotechnology as an area with high interest and potential for rapid implementation of animal free “New Approach Methodologies” (NAMs). Using NAMs, EFSA is committed to support next generation risk assessment approaches while minimizing the use of animal testing, and assuring the “safe by design” concept for new applications.

To implement NAMs, a detailed physicochemical characterization of NMs, which requires several more sophisticated methods and goes far beyond the usual characterization of chemicals, is required.  

This lecture will focus on the development of physicochemical characterization methods to further advance integrated/tiered testing strategies using NAMs and are demonstrated on three different food additives. Methods to determine impurities of nano-additives based on ICP-MS/OES are also shown and can be used as a starting point to develop methodologies to test solubility and dissolution rate, which are key physicochemical properties to determine whether consumers are exposed to nanomaterials after consumption. To envisage hazard of NM, TEM-based approaches combined with image analysis are developed to investigate intrinsic, material specific properties such as constituent particle size and shape distributions, as well as extrinsic environment dependent properties such as agglomeration state.