|
“3D characterization of the structural transformation undergone by Cu@Ag core-shell nanoparticles following CO₂, reduction reaction”. Arenas Esteban D, Pacquets L, Choukroun D, Hoekx S, Kadu AA, Schalck J, Daems N, Breugelmans T, Bals S, Chemistry of materials 35, 6682 (2023). http://doi.org/10.1021/ACS.CHEMMATER.3C00649
Abstract: The increasing use of metallic nanoparticles (NPs) is significantly advancing the field of electrocatalysis. In particular, Cu/Ag bimetallic interfaces are widely used to enhance the electrochemical CO2 reduction reaction (eCO(2)RR) toward CO and, more recently, C-2 products. However, drastic changes in the product distribution and performance when Cu@Ag core-shell configurations are used can often be observed under electrochemical reaction conditions, especially during the first few minutes of the reaction. Possible structural changes that generate these observations remain underexplored; therefore, the structure-property relationship is hardly understood. In this study, we use electron tomography to investigate the structural transformation mechanism of Cu@Ag core-shells NPs during the critical first minutes of the eCO(2)RR. In this manner, we found that the crystallinity of the Cu seed determines whether the formation of a complete and homogeneous Ag shell is possible. Moreover, by tracking the particles' transformations, we conclude that modifications of the Cu-Ag interface and Cu2O enrichment at the surface of the NPs are key factors contributing to the product generation changes. These insights provide a better understanding of how bimetallic core-shell NPs transform under electrochemical conditions.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Applied Electrochemistry & Catalysis (ELCAT)
Impact Factor: 8.6
Times cited: 1
DOI: 10.1021/ACS.CHEMMATER.3C00649
|
|
|
“Phase object reconstruction for 4D-STEM using deep learning”. Friedrich T, Yu C-P, Verbeeck J, Van Aert S, Microscopy and microanalysis 29, 395 (2023). http://doi.org/10.1093/MICMIC/OZAC002
Abstract: In this study, we explore the possibility to use deep learning for the reconstruction of phase images from 4D scanning transmission electron microscopy (4D-STEM) data. The process can be divided into two main steps. First, the complex electron wave function is recovered for a convergent beam electron diffraction pattern (CBED) using a convolutional neural network (CNN). Subsequently, a corresponding patch of the phase object is recovered using the phase object approximation. Repeating this for each scan position in a 4D-STEM dataset and combining the patches by complex summation yields the full-phase object. Each patch is recovered from a kernel of 3x3 adjacent CBEDs only, which eliminates common, large memory requirements and enables live processing during an experiment. The machine learning pipeline, data generation, and the reconstruction algorithm are presented. We demonstrate that the CNN can retrieve phase information beyond the aperture angle, enabling super-resolution imaging. The image contrast formation is evaluated showing a dependence on the thickness and atomic column type. Columns containing light and heavy elements can be imaged simultaneously and are distinguishable. The combination of super-resolution, good noise robustness, and intuitive image contrast characteristics makes the approach unique among live imaging methods in 4D-STEM.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.8
Times cited: 1
DOI: 10.1093/MICMIC/OZAC002
|
|
|
“Synthesis and characterization of a highly electroactive composite based on Au nanoparticles supported on nanoporous activated carbon for electrocatalysis”. Moggia G, Hoekx S, Daems N, Bals S, Breugelmans T, ChemElectroChem , 1 (2023). http://doi.org/10.1002/CELC.202300293
Abstract: A facile, “one-pot”, chemical approach to synthesize gold-based nanoparticles finely dispersed on porous activated carbon (Norit) was demonstrated in this work. The pH of the synthesis bath played a critical role in determining the optimal gold-carbon interaction, which enabled a successful deposition of the gold nanoparticles onto the carbon matrix with a maximized metal utilization of 93 %. The obtained AuNP/C nanocomposite was characterized using SEM, HAADF-STEM electron tomography and electrochemical techniques. It was found that the Au nanoparticles, with diameters between 5 and 20 nm, were evenly distributed over the carbon matrix, both inside and outside the pores. Electrochemical characterization indicated that the composite had a very large electroactive surface area (EASA), as high as 282.4 m2 gAu-1. By exploiting its very high EASA, the catalyst was intended to boost the productivity of glucaric acid in the electrooxidation of its precursor, gluconic acid. However, cyclic voltammetry experiments revealed a very limited reactivity towards gluconic acid oxidation, due to the spacial hindrance of gluconic acid molecule which prevented diffusion inside the catalyst nanopores. On the other hand, the as-synthesized nanocomposite promises to be effective towards the ORR, and might thus find potential application as anode catalyst for fuel cells as well as for the scalability of all those electrochemical reactions involving small molecules with high diffusivity and catalysed by noble metals (i. e. CO2, CH4, N2, etc..). Electrocatalysis: Gold nanoparticles with diameter between 5 and 20 nm evenly distributed onto porous activated carbon (Norit) were obtained using a facile “one-pot” chemical synthesis technique with very high metal utilization. The AuNP/C nanocomposite was characterized using SEM, HAADF-STEM electron tomography and electrochemical techniques, revealing a very large electroactive surface area (EASA). The figure shows the HAADF-STEM image (a) and the respective EDX elemental distribution (b) for the AuNP/C composite with 9.3 % Au-loading developed in this work (Au is marked in red and C in green).image
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Applied Electrochemistry & Catalysis (ELCAT)
Impact Factor: 4
Times cited: 1
DOI: 10.1002/CELC.202300293
|
|
|
“Influence of neutron irradiation on X-ray diffraction, Raman spectrum and photoluminescence from pyrolytic and hot-pressed hexagonal boron nitride”. Zhou S, Xu W, Xiao Y, Xiao H, Zhang J, Wang Z, He G, Liu J, Li Y, Peeters FM, Journal of luminescence 263, 120118 (2023). http://doi.org/10.1016/J.JLUMIN.2023.120118
Abstract: Hexagonal boron nitride (hBN) is considered as an ideal semiconductor material for solid-state neutron detector, owing to its large neutron scattering section because of the low atomic number of B and excellent physical properties. Here we study the influence of neutron irradiation on crystal structure and on intermediate energy state (IMES) levels induced by the presence of impurities and defects in hBN. Large-size and thick pyrolytic and hot-pressed hBN (PBN and HBN) samples, which can be directly applied for neutron detector devices, are prepared and bombarded by neutrons with different irradiation fluences. The SEM and TEM are used to observe the sample difference of PBN and HBN. X-ray diffraction and Raman spectroscopy are applied to examine the influence of neutron irradiation on lattice structures along different crystal directions of PBN and HBN samples. Photoluminescence (PL) is employed to study the effect of neutron irradiation on IMESs in these samples. We find that the neutron irradiation does not alter the in-plane lattice structures of both PBN and HBN samples, but it can release the inter-layer tensions induced by sample growth of the PBN samples. Interestingly and surprisingly, the neutron irradiation does not affect the IMES levels responsible for PL generation, where PL is attributed mainly from phonon-assisted radiative electron-hole coupling for both PBN and HBN samples. Furthermore, the results indicate that the neutron irradiation can weaken the effective carrier-phonon coupling and exciton transitions in PBN and HBN samples. Overall, both PBN and HBN samples show some degree of the resistance to neutron irradiation in terms of these basic physical properties. The interesting and important findings from this work can help us to gain an in-depth understanding of the influence of neutron irradiation on basic physical properties of hBN materials. These effects can be taken into account when designing and applying the hBN materials for neutron detectors.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.6
Times cited: 1
DOI: 10.1016/J.JLUMIN.2023.120118
|
|
|
“Intra-zero-energy Landau level crossings in bilayer graphene at high electric fields”. Xiang F, Gupta A, Chaves A, Krix ZE, Watanabe K, Taniguchi T, Fuhrer MS, Peeters FM, Neilson D, Milošević, MV, Hamilton AR, Nano letters 23, 9683 (2023). http://doi.org/10.1021/ACS.NANOLETT.3C01456
Abstract: The highly tunable band structure of the zero-energy Landau level (zLL) of bilayer graphene makes it an ideal platform for engineering novel quantum states. However, the zero-energy Landau level at high electric fields has remained largely unexplored. Here we present magnetotransport measurements of bilayer graphene in high transverse electric fields. We observe previously undetected Landau level crossings at filling factors nu = -2, 1, and 3 at high electric fields. These crossings provide constraints for theoretical models of the zero-energy Landau level and show that the orbital, valley, and spin character of the quantum Hall states at high electric fields is very different from low electric fields. At high E, new transitions between states at nu = -2 with different orbital and spin polarization can be controlled by the gate bias, while the transitions between nu = 0 -> 1 and nu = 2 -> 3 show anomalous behavior.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 10.8
Times cited: 1
DOI: 10.1021/ACS.NANOLETT.3C01456
|
|
|
“Tuning of exciton type by environmental screening”. Lima ILC, Milošević, MV, Peeters FM, Chaves A, Physical review B 108, 115303 (2023). http://doi.org/10.1103/PHYSREVB.108.115303
Abstract: We theoretically investigate the binding energy and electron-hole (e-h) overlap of excitonic states confined at the interface between two-dimensional materials with type-II band alignment, i.e., with lowest conduction and highest valence band edges placed in different materials, arranged in a side-by-side planar heterostructure. We propose a variational procedure within the effective mass approximation to calculate the exciton ground state and apply our model to a monolayer MoS2/WS2 heterostructure. The role of nonabrupt interfaces between the materials is accounted for in our model by assuming a WxMo1-xS2 alloy around the interfacial region. Our results demonstrate that (i) interface-bound excitons are energetically favorable only for small interface thickness and/or for systems under high dielectric screening by the materials surrounding the monolayer, and that (ii) the interface exciton binding energy and its e-h overlap are controllable by the interface width and dielectric environment.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.7
Times cited: 1
DOI: 10.1103/PHYSREVB.108.115303
|
|
|
“Tailoring weak and metallic phases in a strong topological insulator by strain and disorder : conductance fluctuations signatures”. Shafiei M, Fazileh F, Peeters FM, Milošević, MV, Physical review B 109, 045129 (2024). http://doi.org/10.1103/PHYSREVB.109.045129
Abstract: Transport measurements are readily used to probe different phases in disordered topological insulators (TIs), where determining topological invariants explicitly is challenging. On that note, universal conductance fluctuations (UCF) theory asserts the conductance G for an ensemble has a Gaussian distribution, and that standard deviation 8G depends solely on the symmetries and dimensions of the system. Using a real-space tight -binding Hamiltonian on a system with Anderson disorder, we explore conductance fluctuations in a thin Bi2Se3 film and demonstrate the agreement of their behavior with UCF hypotheses. We further show that magnetic field applied out-of-plane breaks the time -reversal symmetry and transforms the system's Wigner-Dyson class from root symplectic to unitary, increasing 8G by 2. Finally, we reveal that while Bi2Se3 is a strong TI, weak TI and metallic phases can be stabilized in presence of strain and disorder, and detected by monitoring the conductance fluctuations.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.7
Times cited: 1
DOI: 10.1103/PHYSREVB.109.045129
|
|
|
“Atomic resolution mapping using quantitative high-angle annular dark field scanning transmission electron microscopy”. Van Aert S, Verbeeck J, Bals S, Erni R, van Dyck D, Van Tendeloo G, Microscopy and microanalysis 15, 464 (2009). http://doi.org/10.1017/S1431927609093957
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 1.891
Times cited: 1
DOI: 10.1017/S1431927609093957
|
|
|
“Magnetic field dependence of the properties of excitons confined in a quantum disk”. Janssens KL, Peeters FM, Schweigert VA, Physica status solidi: B: basic research 224, 763 (2001). http://doi.org/10.1002/(SICI)1521-3951(200104)224:3<763::AID-PSSB763>3.0.CO;2-9
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.674
Times cited: 1
DOI: 10.1002/(SICI)1521-3951(200104)224:3<763::AID-PSSB763>3.0.CO;2-9
|
|
|
“Skyrmion rows, vortex rows, and phase slip lines in sheared multi-component condensates”. Tempère J, Vermeyen E, Van Duppen B, Physica: C : superconductivity 479, 61 (2012). http://doi.org/10.1016/j.physc.2012.01.016
Abstract: When a condensate is sheared by imparting a velocity to a part of the condensate, phase singularities must appear at the interface between the region that is still at rest and the region that has acquired a velocity. For helium, Feynman argued that these phase singularies will arrange themselves in the form of a vortex row. BoseEinstein condensates of ultracold atomic gases differ from helium in that the healing length is generally much larger and is, in fact, tunable. Another difference is that multicomponent condensates can be created, where the two components forming the mixture are usually two different hyperfine states of the condensed atoms. These two components can be manipulated separately and can be interconverted. In this contribution, we investigate how these additional degrees of freedom, available in quantum gases, change what happens in sheared condensates. In particular, we consider skyrmion rows as an alternative to vortex rows, and we also consider phase slip lines filled with the second, unmoving component, in a condensate mixture. We show that depending on the ratios of the interaction strengths between the components, and depending on the shear velocity, skyrmion rows and phase slip lines can become lower in energy than vortex rows, and hence should be observable in quantum gases. Moreover, we find that the velocity field affects the stability region of the condensate with respect to phase separation.
Keywords: A1 Journal article; Theory of quantum systems and complex systems; Condensed Matter Theory (CMT)
Impact Factor: 1.404
Times cited: 1
DOI: 10.1016/j.physc.2012.01.016
|
|
|
“Vortex states in axially symmetric superconductors in applied magnetic field”. Ludu A, Milošević, MV, Peeters FM, Sn –, 0378-4754 82, 1258 (2012). http://doi.org/10.1016/j.matcom.2012.02.001
Abstract: We solve analytically the linearized Ginzburg-Landau (GL) equation in the presence of an uniform magnetic field with cylindrical boundary conditions. The solution of the non-linear GL equation is provided as an expansion in the basis of linearized solutions. We present examples of the resulting vortex structure for a solid and perforated superconducting cylinder. (C) 2012 IMACS. Published by Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.218
Times cited: 1
DOI: 10.1016/j.matcom.2012.02.001
|
|
|
“Optimization of Automated Crystal Orientation and Phase Mapping in TEM Applied to Ni-Ti All Round Shape Memory Alloy”. Yao X, Li Y, Cao S, Ma X, Zhang X-ping, Schryvers D, MATEC web of conferences
T2 –, Proceedings of ESOMAT 2015 10th European Symposium on Martensitic Transformations, September 14-18, 2015, Antwerp, Belgium 33, 03022 (2015). http://doi.org/10.1051/matecconf/20153303022
Abstract: A new application which focuses on an artificial sphincter fabricated by Ni-Ti SMAs for human implantation is under investigation by applying the all-round shape memory effect with precise control of the phase transformation temperatures. In this study, a Ni51at.%-Ti alloy was fabricated by arc melting with fast solidification, followed by a proper strained aging which induces the two way shape memory effect needed for this particular application. Differential scanning calorimetry was used to investigate the thermal behavior and transmission electron microscopy was used for studying the microstructure of the alloys. With the latter the novel technique of automated crystal orientation microscopy is used and optimized to obtain phase and orientation mapping of the various structures.
Keywords: P1 Proceeding; Electron microscopy for materials research (EMAT)
Times cited: 1
DOI: 10.1051/matecconf/20153303022
|
|
|
“Synthesis, structure and electrochemical properties of LiNaCo0.5Fe0.5PO4F fluoride-phosphate”. Fedotov SS, Kuzovchikov SM, Khasanova NR, Drozhzhin OA, Filimonov DS, Karakulina OM, Hadermann J, Abakumov AM, Antipov EV, Journal of solid state chemistry 242, 70 (2016). http://doi.org/10.1016/j.jssc.2016.02.042
Abstract: LiNaCo 0.5 Fe 0.5 PO 4 F fluoride-phosphate was synthesized via conventional solid-state and novel freeze-drying routes. The crystal structure was refined based on neutron powder diffraction (NPD) data and validated by electron diffraction (ED) and high-resolution transmission electron microscopy (HRTEM). The alkali ions are ordered in LiNaCo 0.5 Fe 0.5 PO 4 F and the transition metals jointly occupy the same crystallographic sites. The oxidation state and oxygen coordination environment of the Fe atoms were verified by 57 Fe Mössbauer spectroscopy. Electrochemical tests of the LiNaCo 0.5 Fe 0.5 PO 4 F cathode material demonstrated a reversible activity of the Fe 3+ /Fe 2+ redox couple at the electrode potential near 3.4 V and minor activity of the Co 3+ /Co 2+ redox couple over 5 V vs Li/Li + . The material exhibits a good capacity retention in the 2.4÷4.6 V vs Li/Li + potential range with the delivered discharge capacity of more than 82% (theo.) regarding Fe 3+ /Fe 2+ .
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.299
Times cited: 1
DOI: 10.1016/j.jssc.2016.02.042
|
|
|
“Elucidating the effects of gas flow rate on an SF6inductively coupled plasma and on the silicon etch rate, by a combined experimental and theoretical investigation”. Tinck S, Tillocher T, Dussart R, Neyts EC, Bogaerts A, Journal of physics: D: applied physics 49, 385201 (2016). http://doi.org/10.1088/0022-3727/49/38/385201
Abstract: Experiments show that the etch rate of Si with SF6 inductively coupled plasma (ICP) is significantly influenced by the absolute gas flow rate in the range of 50–600 sccm, with a maximum at around 200 sccm. Therefore, we numerically investigate the effects of the gas flow rate on the bulk plasma properties and on the etch rate, to obtain more insight in the underlying reasons of this effect. A hybrid Monte Carlo—fluid model is applied to simulate an SF6 ICP. It is found that the etch rate is influenced by two simultaneous effects: (i) the residence time of the gas and (ii) the temperature profile of the plasma in the ICP volume, resulting indeed in a maximum etch rate at 200 sccm.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.588
Times cited: 1
DOI: 10.1088/0022-3727/49/38/385201
|
|
|
“Surface states and positron annihilation spectroscopy: results and prospects from a first-principles approach”. Callewaert V, Saniz R, Barbiellini B, Partoens B, Journal of physics : conference series 791, 012036 (2017). http://doi.org/10.1088/1742-6596/791/1/012036
Abstract: The trapping of positrons at the surface of a material can be exploited to study quite selectively the surface properties of the latter by means of positron annihilation spectroscopy techniques. To support these, it is desirable to be able to theoretically predict the existence of such positronic surface states and to describe their annihilation characteristics with core or valence surface electrons in a reliable way. Here, we build on the well-developed first-principles techniques for the study of positrons in bulk solids as well as on previous models for surfaces, and investigate two schemes that can improve the theoretical description of the interaction of positrons with surfaces. One is based on supplementing the local-density correlation potential with the corrugated image potential at the surface, and the other is based on the weighted-density approximation to correlation. We discuss our results for topological insulators, graphene layers, and quantum dots, with emphasis on the information that can be directly related to experiment. We also discuss some open theoretical problems that should be addressed by future research.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Times cited: 1
DOI: 10.1088/1742-6596/791/1/012036
|
|
|
“New insights into the nanostructure of innovative thin film solar cells gained by positron annihilation spectroscopy”. Eijt SWH, Shi W, Mannheim A, Butterling M, Schut H, Egger W, Dickmann M, Hugenschmidt C, Shakeri B, Meulenberg RW, Callewaert V, Saniz R, Partoens B, Barbiellini B, Bansil A, Melskens J, Zeman M, Smets AHM, Kulbak M, Hodes G, Cahen D, Brück E, Journal of physics : conference series 791, 012021 (2017). http://doi.org/10.1088/1742-6596/791/1/012021
Abstract: Recent studies showed that positron annihilation methods can provide key insights into the nanostructure and electronic structure of thin film solar cells. In this study, positron annihilation lifetime spectroscopy (PALS) is applied to investigate CdSe quantum dot (QD) light absorbing layers, providing evidence of positron trapping at the surfaces of the QDs. This enables one to monitor their surface composition and electronic structure. Further, 2D-Angular Correlation of Annihilation Radiation (2D-ACAR) is used to investigate the nanostructure of divacancies in photovoltaic-high-quality a-Si:H films. The collected momentum distributions were converted by Fourier transformation to the direct space representation of the electron-positron autocorrelation function. The evolution of the size of the divacancies as a function of hydrogen dilution during deposition of a-Si:H thin films was examined. Finally, we present a first positron Doppler Broadening of Annihilation Radiation (DBAR) study of the emerging class of highly efficient thin film solar cells based on perovskites.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Times cited: 1
DOI: 10.1088/1742-6596/791/1/012021
|
|
|
“Plasma processes and polymers third special issue on plasma and cancer”. Laroussi M, Bogaerts A, Barekzi N, Plasma processes and polymers 13, 1142 (2016). http://doi.org/10.1002/ppap.201600193
Keywords: Editorial; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.846
Times cited: 1
DOI: 10.1002/ppap.201600193
|
|
|
“Composition-dependent charge transfer and phase separation in the V1-xRexO2 solid solution”. Mikhailova D, Kuratieva NN, Utsumi Y, Tsirlin AA, Abakumov AM, Schmidt M, Oswald S, Fuess H, Ehrenberg H, Journal of the Chemical Society : Dalton transactions 46, 1606 (2017). http://doi.org/10.1039/C6DT04389E
Abstract: The substitution of vanadium in vanadium dioxide VO2 influences the critical temperatures of structural and metal-to-insulator transitions in different ways depending on the valence of the dopant. Rhenium adopts valence states between + 4 and + 7 in an octahedral oxygen surrounding and is particularly interesting in this context. Structural investigation of V1-xRexO2 solid solutions (0.01 <= x <= 0.30) between 80 and 1200 K using synchrotron X-ray powder diffraction revealed only two polymorphs that resemble VO2: the low-temperature monoclinic MoO2-type form (space group P2(1)/c), and the tetragonal rutile-like form (space group P4(2)/mnm). However, for compositions with 0.03 < x <= 0.15 a phase separation in the solid solution was observed below 1000 K upon cooling down from 1200 K, giving rise to two isostructural phases with slightly different lattice parameters. This is reflected in the appearance of two metal-toinsulator transition temperatures detected by magnetization and specific heat measurements. Comprehensive X-ray photoelectron spectroscopy studies showed that an increased amount of Re leads to a change in the Re valence state from solely Re6+ at a low doping level (<= 3 at% Re) via mixed-valence states Re4+/Re6+ for at least 0.03 < x <= 0.10, up to nearly pure Re4+ in V0.70Re0.30O2. Thus, compositions V1-xRexO2 with only one valence state of Re in the material (Re6+ or Re4+) can be obtained as a single phase, while intermediate compositions are subjected to a phase separation, presumably due to different valence states of Re.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.029
Times cited: 1
DOI: 10.1039/C6DT04389E
|
|
|
“Achieving independent control of core diameter and carbon shell thickness in Pd-C core–shell nanoparticles by gas phase synthesis”. Singh V, Mehta BR, Sengar SK, Karakulina OM, Hadermann J, Kaushal A, Nanotechnology 28, 295603 (2017). http://doi.org/10.1088/1361-6528/aa7660
Abstract: Pd-C core–shell nanoparticles with independently controllable core size and shell thickness are grown by gas phase synthesis. First, the core size is selected by electrical mobility values of charged particles, and second, the shell thickness is controlled by the concentration of carbon precursor gas. The carbon shell grows by adsorption of carbon precursor gas molecules on the surface of nanoparticles, followed by sintering. The presence of a carbon shell on Pd nanoparticles is potentially important in hydrogen-related applications operating at high temperatures or in catalytic reactions in acidic/aqueous environments.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.44
Times cited: 1
DOI: 10.1088/1361-6528/aa7660
|
|
|
“Pressure as an additional control handle for non-thermal atmospheric plasma processes”. Belov I, Paulussen S, Bogaerts A, Plasma processes and polymers 14, 1700046 (2017). http://doi.org/10.1002/ppap.201700046
Abstract: above atmospheric) pressure regimes (1–3.5 bar). It was demonstrated that these operational conditions significantly influence both the discharge dynamics and the process efficiencies of O2 and CO2 discharges. For the case of the O2 DBD, the pressure rise results in the amplification of the discharge current, the appearance of emission lines of the metal electrode material (Fe, Cr, Ni) in the optical emission spectrum and the formation of a granular film of the erosion products (10–300 nm iron oxide nanoparticles) on the reactor walls. Somewhat similar behavior was observed also for the CO2 DBD. The discharge current, the relative intensity of the CO Angstrom band measured by Optical Emission Spectroscopy (OES) and the CO2 conversion rates could be stimulated to some extent by the rise in pressure. The optimal conditions for the O2 DBD (P = 2 bar) and the CO2 DBD (P = 1.5 bar) are demonstrated. It can be argued that the dynamics of the microdischarges (MD) define the underlying process of this behavior. It could be
demonstrated that the pressure increase stimulates the formation of more intensive but fewer MDs. In this way, the operating pressure can represent an additional tool to manipulate the properties of the MDs in a DBD, and as a result also the discharge performance.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.846
Times cited: 1
DOI: 10.1002/ppap.201700046
|
|
|
“StatSTEM: An efficient program for accurate and precise model-based quantification of atomic resolution electron microscopy images”. De Backer A, van den Bos KHW, Van den Broek W, Sijbers J, Van Aert S, Journal of physics : conference series
T2 –, Electron Microscopy and Analysis Group Conference 2017 (EMAG2017), 3-6 July 2017, Manchester, UK 902, 012013 (2017). http://doi.org/10.1088/1742-6596/902/1/012013
Abstract: An efficient model-based estimation algorithm is introduced in order to quantify the atomic column positions and intensities from atomic resolution (scanning) transmission electron microscopy ((S)TEM) images. This algorithm uses the least squares estimator on image segments containing individual columns fully accounting for the overlap between neighbouring columns, enabling the analysis of a large field of view. For this algorithm, the accuracy and precision with which measurements for the atomic column positions and scattering cross-sections from annular dark field (ADF) STEM images can be estimated, is investigated. The highest attainable precision is reached even for low dose images. Furthermore, advantages of the model- based approach taking into account overlap between neighbouring columns are highlighted. To provide end-users this well-established quantification method, a user friendly program, StatSTEM, is developed which is freely available under a GNU public license.
Keywords: P1 Proceeding; Electron microscopy for materials research (EMAT); Vision lab
Times cited: 1
DOI: 10.1088/1742-6596/902/1/012013
|
|
|
“Synthesis and structural characterization of a novel Sillén &ndash, Aurivillius bismuth oxyhalide, PbBi3VO7.5Cl, and its derivatives”. Charkin DO, Plokhikh IV, Kazakov SM, Kalmykov SN, Akinfiev VS, Gorbachev AV, Batuk M, Abakumov AM, Teterin YA, Maslakov KI, Teterin AY, Ivanov KE, Solid state sciences 75, 27 (2018). http://doi.org/10.1016/j.solidstatesciences.2017.11.006
Abstract: A new Sillen – Aurivillius family of layered bismuth oxyhalides has been designed and successfully constructed on the basis of PbBiO2X(X = halogen) synthetic perites and g-form of Bi2VO5.5 solid elec- trolyte. This demonstrates, for the first time, the ability of the latter to serve as a building block in construction of mixed-layer structures. The parent compound PbBi3VO7.5-dCl (d = 0.05) has been investigated by powder XRD, TEM, XPS methods and magnetic susceptibility measurements. An unexpected but important condition for the formation of the mixed-layer structure is partial (ca. 5%) reduction of VV into VIV which probably suppresses competitive formation of apatite-like Pb – Bi vanadates. This reduction also stabilizes the g polymorphic form of Bi2VO5.5 not only in the intergrowth structure, but in Bi2V1-xMxO5.5-y (M – Nb, Sb) solid solutions.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.811
Times cited: 1
DOI: 10.1016/j.solidstatesciences.2017.11.006
|
|
|
“Enhancement of cellular glucose uptake by reactive species: a promising approach for diabetes therapy”. Kumar N, Shaw P, Razzokov J, Yusupov M, Attri P, Uhm HS, Choi EH, Bogaerts A, RSC advances 8, 9887 (2018). http://doi.org/10.1039/C7RA13389H
Abstract: It is generally known that antidiabetic activity is associated with an increased level of glucose uptake in adipocytes and skeletal muscle cells. However, the role of exogenous reactive oxygen and nitrogen species (RONS) in muscle development and more importantly in glucose uptake is largely unknown. We investigate the effect of RONS generated by cold atmospheric plasma (CAP) in glucose uptake. We show that the glucose uptake is significantly enhanced in differentiated L6 skeletal muscle cells after CAP treatment. We also observe a significant increase of the intracellular Ca++ and ROS level, without causing toxicity. One of the possible reasons for an elevated level of glucose uptake as well as intracellular ROS and Ca++ ions is probably the increased oxidative stress leading to glucose transport.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.108
Times cited: 1
DOI: 10.1039/C7RA13389H
|
|
|
“Quantification by aberration corrected (S)TEM of boundaries formed by symmetry breaking phase transformations”. Schryvers D, Salje EKH, Nishida M, De Backer A, Idrissi H, Van Aert S, Ultramicroscopy 176, 194 (2017). http://doi.org/10.1016/j.ultramic.2016.12.022
Abstract: The present contribution gives a review of recent quantification work of atom displacements, atom site occupations and level of crystallinity in various systems and based on aberration corrected HR(S)TEM images. Depending on the case studied, picometer range precisions for individual distances can be obtained, boundary widths at the unit cell level determined or statistical evolutions of fractions of the ordered areas calculated. In all of these cases, these quantitative measures imply new routes for the applications of the respective materials.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.843
Times cited: 1
DOI: 10.1016/j.ultramic.2016.12.022
|
|
|
“Thick secondary phase pinning-enhanced YBCO films on technical templates”. Sieger M, Pahlke P, Lao M, Meledin A, Eisterer M, Van Tendeloo G, Schultz L, Nielsch K, Huehne R, IEEE transactions on applied superconductivity 28, 8000505 (2018). http://doi.org/10.1109/TASC.2018.2799419
Abstract: The critical current I-c(B) of YBa2Cu3O7-delta (YBCO) coated conductors can be increased by growing thicker superconductor layers as well as improving the critical current density J(c)(B) by the incorporation of artificial pinning centers. We studied the properties of pulsed laser deposited BaHfO3 (BHO)-doped YBCO films with thicknesses of up to 5 mu m on buffered rolling-assisted biaxially textured Ni-5 at % W tape and alternating beam assisted deposition textured Yttrium-stabilized ZrO2 layers on stainless steel. X-Ray diffraction confirms the epitaxial growth of the superconductor on the buffered metallic template. BHO additions reduce the film porosity and lower the probability to grow misoriented grains, hence preventing the J(c) decrease observed in undoped YBCO films with thicknesses > 2 mu m. Thereby, a continuous increase in I-c at 77 K is achieved. A mixed structure of secondary phase nanorods and platelets with different orientations increases J(c)(B) in the full angular range and simultaneously lowers the J(c) anisotropy compared to pristine YBCO.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.288
Times cited: 1
DOI: 10.1109/TASC.2018.2799419
|
|
|
“High Coke Resistance of a TiO2Anatase (001) Catalyst Surface during Dry Reforming of Methane”. Huygh S, Bogaerts A, Bal KM, Neyts EC, Journal Of Physical Chemistry C 122, 9389 (2018). http://doi.org/10.1021/acs.jpcc.7b10963
Abstract: The resistance of a TiO2 anatase (001) surface to coke formation was studied in the context of dry reforming of methane using density functional theory (DFT) calculations. As carbon atoms act as precursors for coke formation, the resistance to coke formation can be measured by the carbon coverage of the surface. This is related to the stability of different CHx (x = 0−3) species and their rate of hydrogenation and dehydrogenation on the TiO2 surface. Therefore, we studied the reaction mechanisms and their corresponding rates as a function of the temperature for the dehydrogenation of the species on the surface. We found that the stabilities of C and CH are significantly lower than those of CH3 and CH2. The hydrogenation rates of the different species are significantly higher than the dehydrogenation rates in a temperature range of 300−1000 K. Furthermore, we found that dehydrogenation of CH3, CH2, and CH will only occur at appreciable rates starting from 600, 900, and 900 K, respectively. On the basis of these results, it is clear that the anatase (001) surface has a high coke resistance, and it is thus not likely that the surface will become poisoned by coke during dry reforming of methane. As the rate limiting step in dry reforming is the dissociative adsorption of CH4, we studied an alternative approach to thermal catalysis. We found that the temperature threshold for dry reforming is at least 700 K. This threshold temperature may be lowered by the use of plasma-catalysis, where the appreciable rates of adsorption of plasma-generated CHx radicals result in bypassing the rate limiting step of the reaction.
Keywords: A1 Journal Article; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Impact Factor: 4.536
Times cited: 1
DOI: 10.1021/acs.jpcc.7b10963
|
|
|
“Influence of 4H-SiC substrate miscut on the epitaxy and microstructure of AlGaN/GaN heterostructures”. Gkanatsiou A, Lioutas CB, Frangis N, Polychroniadis EK, Prystawko P, Leszczynski M, Altantzis T, Van Tendeloo G, Materials science in semiconductor processing 91, 159 (2019). http://doi.org/10.1016/j.mssp.2018.11.008
Abstract: AlGaN/GaN heterostructures were grown on “on-axis” and 2° off (0001) 4H-SiC substrates by metalorganic vapor phase epitaxy (MOVPE). Structural characterization was performed by transmission electron microscopy. The dislocation density, being greater in the on-axis case, is gradually reduced in the GaN layer and is forming
dislocation loops in the lower region. Steps aligned along [11̅00] in the off-axis case give rise to simultaneous defect formation. In the on-axis case, an almost zero density of steps is observed, with the main origin of defects probably being the orientation mismatch at the grain boundaries between the small not fully coalesced AlN grains. V-shaped formations are observed in the AlN nucleation layer, but are more frequent in the off-axis case, probably enhanced by the presence of steps. These V-shaped formations are completely overgrown by the GaN layer, during the subsequent deposition, presenting AlGaN areas in the walls of the defect, indicating an interdiffusion between the layers. Finally, at the AlGaN/GaN heterostructure surface in the on-axis case, V-shapes are observed, with the AlN spacer and AlGaN (21% Al) thickness on relaxed GaN exceeding the critical thickness for relaxation. On the other hand, no relaxation in the form of V-shape creation is observed in the off-axis case, probably due to the smaller AlGaN thickness (less than 21% Al). The AlN spacer layer, grown in between the heterostructure, presents a uniform thickness and clear interfaces.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.359
Times cited: 1
DOI: 10.1016/j.mssp.2018.11.008
|
|
|
“Capacitive electrical asymmetry effect in an inductively coupled plasma reactor”. Zhang Q-Z, Bogaerts A, Plasma Sources Science &, Technology 27, 105019 (2018). http://doi.org/10.1088/1361-6595/aad796
Abstract: The electrical asymmetry effect is realized by applying multiple frequency power sources
(13.56 MHz and 27.12 MHz) to a capacitively biased substrate electrode in a specific inductively
coupled plasma reactor. On the one hand, by adjusting the phase angle θ between the multiple
frequency power sources, an almost linear self-bias develops on the substrate electrode, and
consequently the ion energy can be well modulated, while the ion flux stays constant within a
large range of θ. On the other hand, the plasma density and ion flux can be significantly
modulated by tuning the inductive power supply, while only inducing a small change in the self-
bias. Independent control of self-bias/ion energy and ion flux can thus be realized in this specific
inductively coupled plasma reactor.
Keywords: A1 Journal Article; electrical asymmetry effect, inductively coupled plasma, self-bias, independent control of the ion fluxes and ion energy; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Impact Factor: 3.302
Times cited: 1
DOI: 10.1088/1361-6595/aad796
|
|
|
“Nanoscale insight into silk-like protein self-assembly: effect of design and number of repeat units”. Razzokov J, Naderi S, van der Schoot P, Physical biology 15, 066010 (2018). http://doi.org/10.1088/1478-3975/aadb5e
Abstract: By means of replica exchange molecular dynamics simulations we investigate how the length of a silk-like, alternating diblock oligopeptide influences its secondary and quaternary structure. We carry out simulations for two protein sizes consisting of three and five blocks, and study the stability of a single protein, a dimer, a trimer and a tetramer. Initial configurations of our simulations are β-roll and β-sheet structures. We find that for the triblock the secondary and quaternary structures upto and including the tetramer are unstable: the proteins melt into random coil structures and the aggregates disassemble either completely or partially. We attribute this to the competition between conformational entropy of the proteins and the formation of hydrogen bonds and hydrophobic interactions between proteins. This is confirmed by our simulations on the pentablock proteins, where we find that, as the number of monomers in the aggregate increases, individual monomers form more hydrogen bonds whereas their solvent accessible surface area decreases. For the pentablock β-sheet protein, the monomer and the dimer melt as well, although for the β-roll protein only the monomer melts. For both trimers and tetramers remain stable. Apparently, for these the entropy loss of forming β-rolls and β-sheets is compensated for in the free-energy gain due to the hydrogen-bonding and hydrophobic interactions. We also find that the middle monomers in the trimers and tetramers are conformationally much more stable than the ones on the top and the bottom. Interestingly, the latter are more stable on the tetramer than on the trimer, suggesting that as the number of monomers increases protein-protein interactions cooperatively stabilize the assembly.
According to our simulations, the β-roll and β-sheet aggregates must be approximately equally
stable.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Times cited: 1
DOI: 10.1088/1478-3975/aadb5e
|
|
|
“The maximum a posteriori probability rule for atom column detection from HAADF STEM images”. Fatermans J, Van Aert S, den Dekker AJ, Ultramicroscopy 201, 81 (2019). http://doi.org/10.1016/j.ultramic.2019.02.003
Abstract: Recently, the maximum a posteriori (MAP) probability rule has been proposed as an objective and quantitative method to detect atom columns and even single atoms from high-resolution high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) images. The method combines statistical parameter estimation and model-order selection using a Bayesian framework and has been shown to be especially useful for the analysis of the structure of beam-sensitive nanomaterials. In order to avoid beam damage, images of such materials are usually acquired using a limited incoming electron dose resulting in a low contrast-to-noise ratio (CNR) which makes visual inspection unreliable. This creates a need for an objective and quantitative approach. The present paper describes the methodology of the MAP probability rule, gives its step-by-step derivation and discusses its algorithmic implementation for atom column detection. In addition, simulation results are presented showing that the performance of the MAP probability rule to detect the correct number of atomic columns from HAADF STEM images is superior to that of other model-order selection criteria, including the Akaike Information Criterion (AIC) and the Bayesian Information Criterion (BIC). Moreover, the MAP probability rule is used as a tool to evaluate the relation between STEM image quality measures and atom detectability resulting in the introduction of the so-called integrated CNR (ICNR) as a new image quality measure that better correlates with atom detectability than conventional measures such as signal-to-noise ratio (SNR) and CNR.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 2.843
Times cited: 1
DOI: 10.1016/j.ultramic.2019.02.003
|
|