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“Single Crystal and Pentatwinned Gold Nanorods Result in Chiral Nanocrystals with Reverse Handedness”. Van Gordon K, Ni B, Girod R, Mychinko M, Bevilacqua F, Bals S, Liz‐Marzán LM, Angewandte Chemie International Edition (2024). http://doi.org/10.1002/anie.202403116
Abstract: Handedness is an essential attribute of chiral nanocrystals, having a major influence on their properties. During chemical growth, the handedness of nanocrystals is usually tuned by selecting the corresponding enantiomer of chiral molecules involved in asymmetric growth, often known as chiral inducers. We report that, even using the same chiral inducer enantiomer, the handedness of chiral gold nanocrystals can be reversed by using Au nanorod seeds with either single crystalline or pentatwinned structure. This effect holds for chiral growth induced both by amino acids and by chiral micelles. Although it was challenging to discern the morphological handedness for<italic>L</italic>‐cystine‐directed particles, even using electron tomography, both cases showed circular dichroism bands of opposite sign, with nearly mirrored chiroptical signatures for chiral micelle‐directed growth, along with quasi‐helical wrinkles of inverted handedness. These results expand the chiral growth toolbox with an effect that might be exploited to yield a host of interesting morphologies with tunable optical properties.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Impact Factor: 16.6
DOI: 10.1002/anie.202403116
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“Decoding Excimer Formation in Covalent–Organic Frameworks Induced by Morphology and Ring Torsion”. Chakraborty J, Chatterjee A, Molkens K, Nath I, Arenas Esteban D, Bourda L, Watson G, Liu C, Van Thourhout D, Bals S, Geiregat P, Van der Voort P, Advanced materials (2024). http://doi.org/10.1002/adma.202314056
Abstract: A thorough and quantitative understanding of the fate of excitons in covalent–organic frameworks (COFs) after photoexcitation is essential for their augmented optoelectronic and photocatalytic applications via precise structure tuning. The synthesis of a library of COFs having identical chemical backbone with impeded conjugation, but varied morphology and surface topography to study the effect of these physical properties on the photophysics of the materials is herein reported. The variation of crystallite size and surface topography substantified different aggregation pattern in the COFs, which leads to disparities in their photoexcitation and relaxation properties. Depending on aggregation, an inverse correlation between bulk luminescence decay time and exciton binding energy of the materials is perceived. Further transient absorption spectroscopic analysis confirms the presence of highly localized, immobile, Frenkel excitons (of diameter 0.3–0.5 nm) via an absence of annihilation at high density, most likely induced by structural torsion of the COF skeletons, which in turn preferentially relaxes via long‐lived (nanosecond to microsecond) excimer formation (in femtosecond scale) over direct emission. These insights underpin the importance of structural and topological design of COFs for their targeted use in photocatalysis.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 29.4
DOI: 10.1002/adma.202314056
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“Sampling real-time atomic dynamics in metal nanoparticles by combining experiments, simulations, and machine learning”. Cioni M, Delle Piane M, Polino D, Rapetti D, Crippa M, Arslan Irmak E, Van Aert S, Bals S, Pavan GM, Advanced Science , 1 (2024). http://doi.org/10.1002/ADVS.202307261
Abstract: Even at low temperatures, metal nanoparticles (NPs) possess atomic dynamics that are key for their properties but challenging to elucidate. Recent experimental advances allow obtaining atomic-resolution snapshots of the NPs in realistic regimes, but data acquisition limitations hinder the experimental reconstruction of the atomic dynamics present within them. Molecular simulations have the advantage that these allow directly tracking the motion of atoms over time. However, these typically start from ideal/perfect NP structures and, suffering from sampling limits, provide results that are often dependent on the initial/putative structure and remain purely indicative. Here, by combining state-of-the-art experimental and computational approaches, how it is possible to tackle the limitations of both approaches and resolve the atomistic dynamics present in metal NPs in realistic conditions is demonstrated. Annular dark-field scanning transmission electron microscopy enables the acquisition of ten high-resolution images of an Au NP at intervals of 0.6 s. These are used to reconstruct atomistic 3D models of the real NP used to run ten independent molecular dynamics simulations. Machine learning analyses of the simulation trajectories allow resolving the real-time atomic dynamics present within the NP. This provides a robust combined experimental/computational approach to characterize the structural dynamics of metal NPs in realistic conditions. Experimental and computational techniques are bridged to unveil atomic dynamics in gold nanoparticles (NPs), using annular dark-field scanning transmission electron microscopy and molecular dynamics simulations informed by machine learning. The approach provides unprecedented insights into the real-time structural behaviors of NPs, merging state-of-the-art techniques to accurately characterize their dynamics under realistic conditions. image
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 15.1
DOI: 10.1002/ADVS.202307261
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“Single-layered imine-linked porphyrin-based two-dimensional covalent organic frameworks targeting CO₂, reduction”. Arisnabarreta N, Hao Y, Jin E, Salame A, Muellen K, Robert M, Lazzaroni R, Van Aert S, Mali KS, De Feyter S, Advanced energy materials (2024). http://doi.org/10.1002/AENM.202304371
Abstract: The reduction of carbon dioxide (CO2) using porphyrin-containing 2D covalent organic frameworks (2D-COFs) catalysts is widely explored nowadays. While these framework materials are normally fabricated as powders followed by their uncontrolled surface heterogenization or directly grown as thin films (thickness >200 nm), very little is known about the performance of substrate-supported single-layered (approximate to 0.5 nm thickness) 2D-COFs films (s2D-COFs) due to its highly challenging synthesis and characterization protocols. In this work, a fast and straightforward fabrication method of porphyrin-containing s2D-COFs is demonstrated, which allows their extensive high-resolution visualization via scanning tunneling microscopy (STM) in liquid conditions with the support of STM simulations. The as-prepared single-layered film is then employed as a cathode for the electrochemical reduction of CO2. Fe porphyrin-containing s2D-COF@graphite used as a single-layered heterogeneous catalyst provided moderate-to-high carbon monoxide selectivity (82%) and partial CO current density (5.1 mA cm(-2)). This work establishes the value of using single-layered films as heterogene ous catalysts and demonstrates the possibility of achieving high performance in CO2 reduction even with extremely low catalyst loadings.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 27.8
DOI: 10.1002/AENM.202304371
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“Ab initio study of the adsorption of O, O2, H2O and H2O2 on UO2 surfaces using DFT+U and non-collinear magnetism”. Arts I, Saniz R, Baldinozzi G, Leinders G, Verwerft M, Lamoen D, Journal of Nuclear Materials 599, 155249 (2024). http://doi.org/10.1016/j.jnucmat.2024.155249
Abstract: In order to model correctly the corrosion of spent nuclear fuel under disposal conditions, it is important to understand its behavior in the presence of oxidants. To advance in this direction, we consider the oxidation of UO2. We investigate computationally the adsorption of various species on its three most stable surfaces: (111), (110), and (100), with emphasis on incorporating a full non-collinear PBE+U approach. Various species, namely O, O2, H2O and H2O2 are considered due to their relevance for the oxidation of UO2. The dissociation energy and an estimate for the dissociation barrier for O2 were obtained, using the preferred adsorption configurations of O and O2. The adsorption configurations for H2O in our study compare well with previous studies that used collinear approximations, both in terms of relative stability of configurations and bond lengths. Differences in adsorption energies were found, which may be important for reaction kinetics. Dissociative reactions in which the water molecule splits in hydrogen and hydroxyl occur only on one of the three surfaces. The hydrogen further reacts with a surface oxygen to also form a hydroxyl group. Not surprisingly, we find that H2O2 binds more strongly to the three surfaces than water (lower formation energy), and similar to H2O adsorption, dissociative reactions may occur. The dissociated hydrogen reacts with a surface oxygen to form a hydroxyl group and the hydroperoxyl molecule binds with a surface uranium. Our study, which includes a detailed study of electron transfer, magnetic structure and the preferred adsorption configurations, gives insight into the uranium oxidation states and the influence of surface geometry on adsorption. The findings contribute to a more comprehensive understanding of the early stages of UO2 oxidation.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Impact Factor: 3.1
DOI: 10.1016/j.jnucmat.2024.155249
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“Cs3Bi2Br9 nanoparticles decorated C3N4 nanotubes composite photocatalyst for highly selective oxidation of benzylic alcohol”. Ding Y, Wang C, Bandaru S, Pei L, Zheng R, Hau Ng Y, Arenas Esteban D, Bals S, Zhong J, Hofkens J, Van Tendeloo G, Roeffaers MBJ, Chen L-H, Su B-L, Journal of Colloid and Interface Science 672, 600 (2024). http://doi.org/10.1016/j.jcis.2024.06.017
Abstract: Solar-light driven oxidation of benzylic alcohols over photocatalysts endows significant prospects in value-added organics evolution owing to its facile, inexpensive and sustainable process. However, the unsatisfactory performance of actual photocatalysts due to the inefficient charge separation, low photoredox potential and sluggish surface reaction impedes the practical application of this process. Herein, we developed an innovative Z-Scheme Cs3BiBr9 nanoparticles@porous C3N4 tubes (CBB-NP@P-tube-CN) heterojunction photocatalyst for highly selective benzyl alcohol oxidation. Such composite combining increased photo-oxidation potential, Z-Scheme charge migration route as well as the structural advantages of porous tubular C3N4 ensures the accelerated mass and ions diffusion kinetics, the fast photoinduced carriers dissociation and sufficient photoredox potentials. The CBB-NP@P-tube-CN photocatalyst demonstrates an exceptional performance for selective photo-oxidation of benzylic alcohol into benzaldehyde with 19, 14 and 3 times higher benzylic alcohols conversion rate than those of C3N4 nanotubes, Cs3Bi2Br9 and Cs3Bi2Br9@bulk C3N4 photocatalysts, respectively. This work offers a sustainable photocatalytic system based on lead-free halide perovskite toward large scale solar-light driven value-added chemicals production.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Impact Factor: 9.9
DOI: 10.1016/j.jcis.2024.06.017
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“In SituStudy of the Activation Process of MOF-74 Using Three-Dimensional Electron Diffraction”. Quintelier M, Hajizadeh A, Zintler A, Gonçalves BF, Fernández de Luis R, Esrafili Dizaji L, Vande Velde CML, Wuttke S, Hadermann J, Chemistry of Materials (2024). http://doi.org/10.1021/acs.chemmater.4c01153
Abstract: Metal–organic framework (MOF)-74 is known for its effectiveness in selectively capturing carbon dioxide (CO2). Especially the Zn and Cu versions of MOF-74 show high efficiency of this material for CO2. However, the activation of this MOF, which is a crucial step for its utilization, is so far not well understood. Here, we are closing the knowledge gap by examining the activation using, for the first time in the MOF, three-dimensional electron diffraction (3DED) during in situ heating. The use of state-of-the-art direct electron detectors enables rapid acquisition and minimal exposure times, therefore minimizing beam damage to the very electron beam-sensitive MOF material. The activation process of Zn-MOF-74 and Cu-MOF-74 is systematically studied in situ, proving the creation of open metal sites. Differences in thermal stability between Zn-MOF-74 and Cu-MOF-74 are attributed to the strength of the metal–oxygen bonds and Jahn–Teller distortions. In the case of Zn-MOF-74, we observe previously unknown remaining electrostatic potentials inside the MOF pores, which indicate the presence of remaining atoms that might impede gas flow throughout the structure when using the MOF for absorption purposes. We believe our study exemplifies the significance of employing advanced characterization techniques to enhance our material understanding, which is a crucial step for unlocking the full potential of MOFs in various applications.
Keywords: A1 Journal Article; 3DED; MOFs; in situ; Electron Microscopy for Materials Science (EMAT) ;
Impact Factor: 8.6
DOI: 10.1021/acs.chemmater.4c01153
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“Direct visualization of ligands on gold nanoparticles in a liquid environment”. Pedrazo-Tardajos A, Claes N, Wang D, Sánchez-Iglesias A, Nandi P, Jenkinson K, De Meyer R, Liz-Marzán LM, Bals S, Nature Chemistry (2024). http://doi.org/10.1038/s41557-024-01574-1
Abstract: The interaction among Au nanoparticles, their surface ligands and the solvent critically influences the properties of nanoparticles. Despite employing spectroscopic and scattering techniques to investigate their ensemble structure, a comprehensive understanding at the nanoscale remains elusive. Electron microscopy enables characterization of the local structure and composition but is limited by insufficient contrast, electron beam sensitivity and ultra-high vacuum, which prevent the investigation of dynamic aspects. Here we show that, by exploiting high-quality graphene liquid cells, we can overcome these limitations and investigate the structure of the ligand shell around the Au nanoparticles, as well as the ligand-Au interface in a liquid environment. Using this graphene liquid cell, we visualize the anisotropy, composition and dynamics of ligand distribution at the Au nanorod surface. Our results indicate a micellar model for the surfactant organisation. This work opens up a reliable and direct visualization of ligand distribution around colloidal nanoparticles.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Impact Factor: 21.8
DOI: 10.1038/s41557-024-01574-1
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“Insight on Zn-Al LDH as electrocatalyst for CO2 reduction reaction: An in-situ ATR-IR study”. Cavallo M, Dosa M, Nakazato R, Porcaro NG, Signorile M, Quintelier M, Hadermann J, Bordiga S, Rosero-Navarro NC, Tadanaga K, Crocellà, V, Bonino F, Journal of CO2 Utilization 83, 102804 (2024). http://doi.org/10.1016/j.jcou.2024.102804
Abstract: Electrochemical reduction of CO2 (CO2RR) is expected to play a key role among the various strategies being explored to limit global warming. In this scenario, Layered Double Hydroxides (LDHs) are emerging as a promising class of electrocatalysts to replace the most used noble metals. In this work three Zn-Al LDH with different Zn2+/Al3+ ratio were synthesized and characterized by means of XRD, STEM-EDX and HR-TEM. Their suitability for CO2RR to CO was assessed by means of a custom-made three-compartment cell, showing an increase in CO selectivity by decreasing the Zn2+/Al3+ ratio. The CO2 interaction with the samples was firstly
characterized by means of volumetric adsorption measurements, exhibiting an increase in capture capacity by decreasing the Zn2+/Al3+ ratio. The evolution of the samples in interaction with a CO2-saturated liquid flow was then deeply investigated by means of in-situ ATR-IR spectroscopy. The samples displayed a different evolution in the vibrational region of the carbonate-like species (1800–1200 cm???? 1). To better discriminate the different carbonate cyclohexane was also employed. A definitive assignment of the main IR bands of the carbonate was
carried out by studying the spectral behavior of the different bands observed in the ATR-IR experiments and by comparing these results with the existing literature. Interestingly, Zn-Al 1:2 LDH, the most efficient electrocatalyst for CO2RR, is also the sole sample exhibiting a higher monodentate to total bidentate carbonates ratio, suggesting that the existence of a higher content of low coordination oxygen anions with stronger basic character can influence the final catalytic activity.
Keywords: A1 Journal Article; In-situ ATR-IR spectroscopy; Layered Double Hydroxide; CO2 reduction reaction; Electrocatalysis; Electron Microscopy for Materials Science (EMAT) ;
Impact Factor: 7.7
DOI: 10.1016/j.jcou.2024.102804
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“The effect of the acceleration voltage on the quality of structure determination by 3D-electron diffraction”. Gholam S, Hadermann J, Ultramicroscopy 266, 114022 (2024). http://doi.org/10.1016/j.ultramic.2024.114022
Abstract: Nowadays, 3D Electron Diffraction (3DED) is widely used for the structure determination of sub-micron-sized particles. In this work, we investigate the influence of the acceleration voltage on the quality of 3DED datasets acquired on BaTiO3 nanoparticles. Datasets were acquired using a wide range of beam energies, from common, high acceleration voltages (300 kV and 200 kV) to medium (120 kV and 80 kV) and low acceleration voltages (60 kV and 30 kV). In the integration process, Rint increases as the beam energy reduces, which is mainly due to the increased dynamical scattering. Nevertheless, the structure was solved successfully in all cases. The structure refinement was comparable for all beam energies with small deficiencies such as negative atomic displacements for the heaviest atom in the structure, barium. Including extinction correction in the refinement noticeably improved the model for low acceleration voltages, probably due to higher beam absorption in these cases. Dynamical refinement, however, shows superior results for higher acceleration voltages, since the dynamical refinement calculations currently discard inelastic scattering effects.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Impact Factor: 2.2
DOI: 10.1016/j.ultramic.2024.114022
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“Obtaining 3D Atomic Reconstructions from Electron Microscopy Images Using a Bayesian Genetic Algorithm: Possibilities, Insights, and Limitations”. Stoops T, De Backer A, Lobato I, Van Aert S, Microscopy and Microanalysis (2024). http://doi.org/10.1093/mam/ozae090
Abstract: The Bayesian genetic algorithm (BGA) is a powerful tool to reconstruct the 3D structure of mono-atomic single-crystalline metallic nanoparticles imaged using annular dark field scanning transmission electron microscopy. The number of atoms in a projected atomic column in the image is used as input to obtain an accurate and atomically precise reconstruction of the nanoparticle, taking prior knowledge and the finite precision of atom counting into account. However, as the number of parameters required to describe a nanoparticle with atomic detail rises quickly with the size of the studied particle, the computational costs of the BGA rise to prohibitively expensive levels. In this study, we investigate these computational costs and propose methods and control parameters for efficient application of the algorithm to nanoparticles of at least up to 10 nm in size.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Impact Factor: 2.8
DOI: 10.1093/mam/ozae090
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“Optimization of three-dimensional electron diffuse scattering data acquisition”. Poppe R, Hadermann J, Ultramicroscopy 265, 114023 (2024). http://doi.org/10.1016/j.ultramic.2024.114023
Abstract: The diffraction patterns of crystalline materials with local order contain sharp Bragg reflections as well as highly structured diffuse scattering. In this study, we quantitatively show how the diffuse scattering in three-dimensional electron diffraction (3D ED) data is influenced by various parameters, including the data acquisition mode, the detector type and the use of an energy filter. We found that diffuse scattering data used for quantitative analysis are preferably acquired in selected area electron diffraction (SAED) mode using a CCD and an energy filter. In this study, we also show that the diffuse scattering in 3D ED data can be obtained with a quality comparable to that from single-crystal X-ray diffraction. As electron diffraction requires much smaller crystal sizes than X-ray diffraction, this opens up the possibility to investigate the local structure of many technologically relevant materials for which no crystals large enough for single-crystal X-ray diffraction are available.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Impact Factor: 2.2
DOI: 10.1016/j.ultramic.2024.114023
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“Core–Shell Colloidal Nanocomposites for Local Temperature Monitoring during Photothermal Heating”. Zani V, Renero-Lecuna C, Jimenez de Aberasturi D, di Silvio D, Kavak S, Bals S, Signorini R, Liz-Marzán LM, The Journal of Physical Chemistry C (2024). http://doi.org/10.1021/acs.jpcc.4c05593
Abstract: Determining temperature changes at the heating site to accurately control thermal treatments has been a major goal in the field of nanothermometry. In this study, we address the need to effectively monitor local temperature during the application of photothermal therapies, which is essential to prevent uncontrolled heating induced by nanoparticle sensitizers used in such treatments. For this purpose, we developed a synthetic protocol to produce a nanocomposite probe that allows local photothermal heating and simultaneous in situ optical nanothermometry, within the biological transparency windows. The nanocomposite material comprises gold nanorods for light-to-heat conversion and neodymium (Nd3+)-based nanoparticles for local temperature monitoring. An inert spacer made of mesoporous silica provides a core-shell structure and ensures uniform separation between both functionalities to prevent photoluminescence quenching. By using an 808 nm laser as the source for both heating and photoluminescence excitation, we demonstrate a direct correlation between local temperature and near infrared Nd3+ emission intensities, thereby providing precise local temperature monitoring. Different levels of local heating were studied by varying the incident laser power, resulting in a maximum temperature increase of 47 °C detected with the nanothermometers. Albeit presented here as a proof of concept, this concept can be translated to the design of materials for photothermal therapy.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Impact Factor: 3.7
DOI: 10.1021/acs.jpcc.4c05593
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“Ab initio based atomic scattering amplitudes and {002} electron structure factors of InxGa1-xAs/GaAs quantum wells”. Titantah JT, Lamoen D, Schowalter M, Rosenauer A, Journal of physics : conference series 209, 012040 (2010). http://doi.org/10.1088/1742-6596/209/1/012040
Abstract: The atomic scattering amplitudes of the various atoms of the systems Ga1−xInxAs, GaAs1−xNx and InAs1−xNx are calculated using the density functional theory (DFT) approach. The scattering amplitudes of N, Ga, As and In in the model systems are compared with the frequently used Doyle and Turner values. Deviation from the latter values is found for small scattering vectors (s<0.3Å−1) and for these scattering vectors dependence on the orientation of the scattering vector and the chemical environment is reported. We suggest a parametrization of these modified scattering amplitudes (MASAs) for small scattering vectors (s<1.0Å−1). The MASAs are exploited within zero pressure classical Metropolis Monte Carlo (MC), finite temperature calculations to investigate the effect of quantum well size on the electron {002} structure factor (SF) of Ga1−xInxAs quantum wells.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.1088/1742-6596/209/1/012040
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“Ab initio calculation of the energy-loss near-edge structure of some carbon allotropes: comparison with n-diamond”. Dadsetani M, Titantah JT, Lamoen D, Diamond and related materials 19, 73 (2010). http://doi.org/10.1016/j.diamond.2009.11.004
Abstract: The energy-loss near-edge structure (ELNES) spectra of several carbon allotropes (non-hydrogenated and hydrogenated face-centered cubic (FCC) carbon, rhombohedral carbon, glitter, hexagonite and lonsdaleite) are calculated within the supercell-core-excited density functional theory approach. In particular an experimental ELNES spectrum of new diamond (n-diamond) [Konyashin et al., Diamond Relat. Mater. 10, (2001) 99102] is compared with the ELNES spectra of FCC carbon, rhombohedral carbon and the so-called glitter structure. Our calculations show that the ELNES spectrum considered in that publication cannot be that of FCC carbon.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.561
Times cited: 11
DOI: 10.1016/j.diamond.2009.11.004
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“Adsorption of sulfur onto a surface of silver nanoparticles stabilized with sago starch biopolymer”. Djoković, V, Krsmanović, R, Božanić, DK, McPherson M, Van Tendeloo G, Nair PS, Georges MK, Radhakrishnan T, Colloids and surfaces: B : biointerfaces 73, 30 (2009). http://doi.org/10.1016/j.colsurfb.2009.04.022
Abstract: Adsorption of sulfide ions onto a surface of starch capped silver nanoparticles upon addition of thioacetamide was investigated. UVvis absorption spectroscopy revealed that the adsorption of the sulfide ion on the surface of the silver nanoparticles induced damping as well as blue shift of the silver surface plasmon resonance band. Further increase in thioacetamide concentration led to shift of the resonance band toward higher wavelengths indicating the formation of the continuous Ag2S layer on the silver surface. Thus fabricated nanoparticles were investigated using electron microscopy techniques (TEM, HRTEM, and HAADF-STEM) and X-ray photoelectron spectroscopy (XPS), which confirmed their coreshell structure.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.887
Times cited: 41
DOI: 10.1016/j.colsurfb.2009.04.022
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“Advanced electron microscopy characterisation of important precipitation and ordering phenomena in shape memory systems”. Schryvers D, Shape memory and superelasticity 1, 78 (2015). http://doi.org/10.1007/s40830-015-0006-3
Abstract: The present paper discusses some important aspects of precipitation and ordering in alloy systems that show a martensitic transformation and can or are used as shape memory or superelastic metallic systems. The precipitates are investigated by a variety of conventional and advanced electron microscopy techniques, including atomic resolution, 3D slice-and-view, energy loss spectroscopy etc. Depending on the system, such secondary phases can decrease the probability of a displacive transformation by changing the phase stability in the system, such as in the case of NiAl or NiTiPd, or can mechanically hinder the passage of the transformation interface, as in NiTiNb. On the other hand, properly controlling the nucleation and growth of some precipitates can strongly improve the properties of some types of materials, as is the case for the well-known Ni4Ti3 precipitates.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.1007/s40830-015-0006-3
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“Advanced three-dimensional electron microscopy techniques in the quest for better structural and functional materials”. Schryvers D, Cao S, Tirry W, Idrissi H, Van Aert S, Science and technology of advanced materials 14, 014206 (2013). http://doi.org/10.1088/1468-6996/14/1/014206
Abstract: After a short review of electron tomography techniques for materials science, this overview will cover some recent results on different shape memory and nanostructured metallic systems obtained by various three-dimensional (3D) electron imaging techniques. In binary NiTi, the 3D morphology and distribution of Ni4Ti3 precipitates are investigated by using FIB/SEM slice-and-view yielding 3D data stacks. Different quantification techniques will be presented including the principal ellipsoid for a given precipitate, shape classification following a Zingg scheme, particle distribution function, distance transform and water penetration. The latter is a novel approach to quantifying the expected matrix transformation in between the precipitates. The different samples investigated include a single crystal annealed with and without compression yielding layered and autocatalytic precipitation, respectively, and a polycrystal revealing different densities and sizes of the precipitates resulting in a multistage transformation process. Electron tomography was used to understand the interaction between focused ion beam-induced Frank loops and long dislocation structures in nanobeams of Al exhibiting special mechanical behaviour measured by on-chip deposition. Atomic resolution electron tomography is demonstrated on Ag nanoparticles in an Al matrix.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.798
Times cited: 6
DOI: 10.1088/1468-6996/14/1/014206
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“Aerosol synthesis of fullerene nanocrystals in controlled flow reactor conditions”. Joutsensaari J, Ahonen PP, Kauppinen EI, Brown DP, Lehtinen KEJ, Jokiniemi JK, Pauwels B, Van Tendeloo G, Journal of nanoparticle research 2, 53 (2000)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.02
Times cited: 5
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“Atomic structure of quantum gold nanowires : quantification of the lattice strain”. Kundu P, Turner S, Van Aert S, Ravishankar N, Van Tendeloo G, ACS nano 8, 599 (2014). http://doi.org/10.1021/nn4052315
Abstract: Theoretical studies exist to compute the atomic arrangement in gold nanowires and the influence on their electronic behavior with decreasing diameter. Experimental studies, e.g., by transmission electron microscopy, on chemically synthesized ultrafine wires are however lacking owing to the unavailability of suitable protocols for sample preparation and the stability of the wires under electron beam irradiation. In this work, we present an atomic scale structural investigation on quantum single crystalline gold nanowires of 2 nm diameter, chemically prepared on a carbon film grid. Using low dose aberration-corrected high resolution (S)TEM, we observe an inhomogeneous strain distribution in the crystal, largely concentrated at the twin boundaries and the surface along with the presence of facets and surface steps leading to a noncircular cross section of the wires. These structural aspects are critical inputs needed to determine their unique electronic character and their potential as a suitable catalyst material. Furthermore, electron-beam-induced structural changes at the atomic scale, having implications on their mechanical behavior and their suitability as interconnects, are discussed.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 20
DOI: 10.1021/nn4052315
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“Behavior of Ni-doped MgMoO4 single-phase catalysts for synthesis of multiwalled carbon nanotube bundles”. Li Y, Zhang X, Geise HJ, Van Tendeloo G, Chemical vapor deposition 13, 30 (2007). http://doi.org/10.1002/cvde.200606531
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.333
Times cited: 4
DOI: 10.1002/cvde.200606531
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“Catalytic and molecular separation properties of Zeogrids and Zeotiles”. Martens JA, Thybaut JW, Denayer JFM, Sree SP, Aerts A, Reyniers M-F, van Speybroeck V, Waroquier M, Buekenhoudt A, Vankelecom I, Buijs W, Persoons J, Baron GV, Bals S, Van Tendeloo G, Marin GB, Jacobs PA, Kirschhock CEA, Catalysis today 168, 17 (2011). http://doi.org/10.1016/j.cattod.2011.01.036
Abstract: Zeogrids and Zeotiles are hierarchical materials built from assembled MFI zeolite precursor units. Permanent secondary porosity in these materials is obtained through self assembly of nanoparticles encountered in MFI zeolite synthesis in the presence of supramolecular templates. Hereon, the aggregated species are termed nanoslabs. Zeogrids are layered materials with lateral spacings between nanoslabs creating galleries qualifying as supermicropores. Zeotiles present a diversity of tridimensional nanoslab assemblies with mesopores. Zeotile-1, -4 and -6 are hexagonal mesostructures. Zeotile-1 has triangular and hexagonal channels; Zeotile-4 has hexagonal channels interconnected via slits. Zeotile-2 has a cubic structure with gyroid type mesoporosity. The behavior of Zeogrids and Zeotiles in adsorption, membrane and chromatographic separation and catalysis has been characterized and compared with zeolites and mesoporous materials derived from unstructured silica sources. Shape selectivity was detected via adsorption of n- and iso-alkanes. The mesoporosity of Zeotiles can be exploited in chromatographic separation of biomolecules. Zeotiles present attractive separation properties relevant to CO2 sequestration. Because of its facile synthesis procedure without hydrothermal steps Zeogrid is convenient for membrane synthesis. The performance of Zeogrid membrane in gas separation, nanofiltration and pervaporation is reported. In the Beckmann rearrangement of cyclohexanone oxime Zeogrids and Zeotiles display a catalytic activity characteristic of silicalite-1 zeolites. Introduction of acidity and redox catalytic activity can be achieved via incorporation of Al and Ti atoms in the nanoslabs during synthesis. Zeogrids are active in hydrocracking, catalytic cracking, alkylation and epoxidation reactions. Zeogrids and Zeotiles often behave differently from ordered mesoporous materials as well as from zeolites and present a valuable extension of the family of hierarchical silicate based materials.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.636
Times cited: 13
DOI: 10.1016/j.cattod.2011.01.036
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“Characterization of nickel silicides using EELS-based methods”. Verleysen E, Bender H, Richard O, Schryvers D, Vandervorst W, Journal of microscopy 240, 75 (2010). http://doi.org/10.1111/j.1365-2818.2010.03391.x
Abstract: The characterization of Ni-silicides using electron energy loss spectroscopy (EELS) based methods is discussed. A series of Ni-silicide phases is examined: Ni3Si, Ni31Si12, Ni2Si, NiSi and NiSi2. The composition of these phases is determined by quantitative core-loss EELS. A study of the low loss part of the EELS spectrum shows that both the energy and the shape of the plasmon peak are characteristic for each phase. Examination of the Ni-L edge energy loss near edge structure (ELNES) shows that the ratio and the sum of the L2 and L3 white line intensities are also characteristic for each phase. The sum of the white line intensities is used to determine the trend in electron occupation of the 3d states of the phases. The dependence of the plasmon energy on the electron occupation of the 3d states is demonstrated.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.692
Times cited: 11
DOI: 10.1111/j.1365-2818.2010.03391.x
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“The chemical vapor infiltration of exfoliated graphite to produce carbon/carbon composites”. Tikhomirov AS, Sorokina NE, Shornikova ON, Morozov VA, Van Tendeloo G, Avdeev VV, Carbon 49, 147 (2011). http://doi.org/10.1016/j.carbon.2010.08.054
Abstract: Chemical vapor infiltration was used for the production of carbon/carbon composites based on exfoliated graphite and pyrolytic carbon Two different exfoliated graphites compacted to densities of 0 05-0 4 g/cm(3) were used as a preform The influence of the synthesis conditions (temperature, pressure, time etc) on the degree of infiltration, the pyrolytic carbon morphology and the C/C composite characteristics was examined using Raman spectroscopy, scanning electron microscopy and low-temperature nitrogen adsorption (C) 2010 Elsevier Ltd All rights reserved
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 6.337
Times cited: 7
DOI: 10.1016/j.carbon.2010.08.054
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“Computation and parametrization of the temperature dependence of Debye-Waller factors for group IV, III-V and II-VI semiconductors”. Schowalter M, Rosenauer A, Titantah JT, Lamoen D, Acta crystallographica: section A: foundations of crystallography 65, 5 (2009). http://doi.org/10.1107/S0108767308031437
Abstract: We calculated the temperature dependence of the Debye-Waller factors for a variety of group IV, III-V and II-VI semiconductors from 0.1 to 1000 K. The approach used to fit the temperature dependence is described and resulting fit parameters are tabulated for each material. The Debye-Waller factors are deduced from generalized phonon densities of states which were derived from first principles using the WIEN2k and the ABINIT codes.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 5.725
Times cited: 51
DOI: 10.1107/S0108767308031437
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“Conformational analysis of TMC114, a novel HIV-1 protease inhibitor”. Nivesanond K, Peeters A, Lamoen D, van Alsenoy C, Journal of Chemical Information and Modeling 48, 99 (2008). http://doi.org/10.1021/ci7001318
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.76
Times cited: 13
DOI: 10.1021/ci7001318
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“Controllable synthesis of novel one-dimensional carbon nanomaterials on an alkali-element-modified Cu catalyst”. Tao XY, Zhang XB, Cheng J-P, Liu F, Li Y, Van Tendeloo G, Nanotechnology 17, 224 (2006). http://doi.org/10.1088/0957-4484/17/1/037
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.44
Times cited: 4
DOI: 10.1088/0957-4484/17/1/037
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“Correlation of microstructure and magnetotransport properties of epitaxially grown La-Ca-Mn-O3 thin films”. Habermeier HU, Razavi F, Lebedev O, Gross GM, Praus R, Zhang PX, Physica status solidi: B: basic research
T2 –, International Conference on Solid State Spectroscopy –, (ICSSS), SEP 05-07, 1999, SCHWABISCH-GMUND, GERMANY 215, 679 (1999). http://doi.org/10.1002/(SICI)1521-3951(199909)215:1<679::AID-PSSB679>3.0.CO;2-H
Abstract: We have investigated epitaxially grown single-crystalline Ca-doped LaMnO3 thin films using the pulsed laser deposition technique in a case study aimed to explore the possibilities buried in epitaxial stress tailoring in order to control the transport properties of CMR materials beyond the limits set by equilibrium thermodynamics. Depending on the film thickness there is an abrupt transition from pseudomorphic to epitaxial granular growth observable which is related to the epitaxial strain of the films. This is associated with microscopic stress relaxation and leads to well controllable modifications of the atomic arrangements of the Mn-O sublattice in the films. Due to the interrelation of double exchange, spin-, charge- and orbital ordering and the Jahn-Teller effect mediated coupling of the electronic system to the crystal lattice, the magnetotransport properties of the firms can be modified in a controllable way.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.674
Times cited: 3
DOI: 10.1002/(SICI)1521-3951(199909)215:1<679::AID-PSSB679>3.0.CO;2-H
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“Critical size for exchange bias in ferromagnetic-antiferromagnetic particles”. Dobrynin AN, Ievlev DN, Temst K, Lievens P, Margueritat J, Gonzalo J, Afonso CN, Zhou SQ, Vantomme A, Piscopiello E, Van Tendeloo G, Applied physics letters 87, 012501 (2005). http://doi.org/10.1063/1.1978977
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.411
Times cited: 92
DOI: 10.1063/1.1978977
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“Crystal growth of CsCl-type Yb0.24Sn0.76Ru”. Klimczuk T, Wang CH, Xu Q, Lawrence J, Durakiewicz T, Ronning F, Llobet A, Bauer ED, Griveau J-C, Sadowski W, Zandbergen HW, Thompson JD, Cava RJ, Journal of crystal growth 318, 1005 (2011). http://doi.org/10.1016/j.jcrysgro.2010.10.045
Abstract: The YbRuSn ternary system was investigated and a new material, Yb0.24Sn0.76Ru, with a simple cubic crystal structure, was discovered. Yb0.24Sn0.76Ru has a smaller lattice parameter a=3.217(4) Å, than its isostructural YbRu analogue (a=3.360 Å). Both X-ray diffraction and electron microscopy techniques were used to refine the crystal structure of Yb0.24Sn0.76Ru. It was found that a new compound forms in the CsCl structure, with Ru on the 1a site and a (Yb, Sn) mixture on site 1b. The XRD Rietveld analysis provides the occupation of Yb equal to 0.24, in agreement with the single crystal nano-electron diffraction refinement, which gives the occupation 0.21.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.751
Times cited: 1
DOI: 10.1016/j.jcrysgro.2010.10.045
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