“Accuracy and precision in model based EELS quantification”. Bertoni G, Verbeeck J, Ultramicroscopy 108, 782 (2008). http://doi.org/10.1016/j.ultramic.2008.01.004
Abstract: We present results on model based quantification of electron energy loss spectra (EELS), focusing on the factors that influence accuracy and precision in determining chemical concentrations. Several sources of systematical errors are investigated. The spectrometer entrance aperture determines the collection angle, and the effects of its position with respect to the transmitted beam are investigated, taking into account the diffraction by the crystal structure. The effect of the orientation of the sample is tested experimentally and theoretically on SrTiO3, and finally, a simulated experiment on c-BN at different thicknesses confirms the superior results of the model based method with respect to the conventional method. A test on a set of experimental reference compounds is presented, showing that remarkably good accuracy can be obtained. Recommendations are given to achieve high accuracy and precision in practice. (C) 2008 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.843
Times cited: 44
DOI: 10.1016/j.ultramic.2008.01.004
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“Advanced TEM investigation of the plasticity mechanisms in nanocrystalline freestanding palladium films with nanoscale twins”. Wang B, Idrissi H, Galceran M, Colla MS, Turner S, Hui S, Raskin JP, Pardoen T, Godet S, Schryvers D, International journal of plasticity 37, 140 (2012). http://doi.org/10.1016/j.ijplas.2012.04.003
Abstract: Nanocrystalline palladium thin films deposited by electron-beam evaporation and deformed by on-chip tensile testing reveal a surprisingly large strain hardening capacity when considering the small similar to 25 nm grain size. The as-grown films contain several coherent single and multifold twin boundaries. The coherency of the twin boundaries considerably decreases with deformation due to dislocation/twin boundary interactions. These reactions are described based on a detailed analysis of the number and the type of dislocations located at the twin boundaries using high-resolution TEM, including aberration corrected microscopy. Sessile Frank dislocations were observed at the twin/matrix interfaces, explaining the loss of the TB coherency due to the Burgers vector pointing out of the twinning plane. Grain boundary mediated processes were excluded as a mechanism dominating the plastic deformation based on the investigation of the grain size distribution as well as the crystallographic texture using Automated Crystallographic Orientation Indexation TEM. Other factors influencing the plastic deformation such as impurities and the presence of a native passivation oxide layer at the surface of the films were investigated using analytical TEM. The twin boundaries observed in the present work partly explain the high strain hardening capacity by providing both increasing resistance to dislocation motion with deformation and a source for dislocation multiplication. (C) 2012 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 5.702
Times cited: 44
DOI: 10.1016/j.ijplas.2012.04.003
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“Configuration-interaction excitonic absorption in small Si/Ge and Ge/Si core/shell nanocrystals”. de Oliveira EL, Albuquerque EL, de Sousa JS, Farias GA, Peeters FM, The journal of physical chemistry: C : nanomaterials and interfaces 116, 4399 (2012). http://doi.org/10.1021/jp2088516
Abstract: The excitonic properties of Si(core)/Ge(shell) and Ge(core)/Si(shell) nanocrystals (NC's) with diameters of similar to 1.9 nm are investigated using a combination density functional ab initio method to obtain the single particle wave functions and a configuration interaction method to compute the exciton fine structure and absorption coefficient. These core/shell structures exhibit type II confinement, which is more pronounced for the Si/Ge NC as a consequence of strain. The absorption coefficients of these NC's exhibit a single dominant peak, which has a much larger oscillator strength than the multipeaks found for pure Si and Ge NC's. The exciton lifetime in Si, Ge, and Ge/Si shows a small i:emperature dependence in the range 10-300 K, whereas in Si/Ge, the exciton lifetime decreases more than an order of magnitude in the same temperature range.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 4.536
Times cited: 44
DOI: 10.1021/jp2088516
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“Direct evidence of spontaneous quantum dot formation in a thick InGaN epilayer”. Nistor L, Bender H, Vantomme A, Wu MF, van Landuyt J, O'Donnell KP, Martin R, Jacobs K, Moerman I, Applied physics letters 77, 507 (2000). http://doi.org/10.1063/1.127026
Abstract: We report a direct observation of quantum dots formed spontaneously in a thick InGaN epilayer by high resolution transmission electron microscopy. Investigation of a (280 nm thick) In0.22Ga0.78N single layer, emitting in the blue/green spectral region, reveals quantum dots with estimated sizes in the range of 1.5-3 nm. Such sizes are in very good agreement with calculations based on the luminescence spectra of this specimen. (C) 2000 American Institute of Physics. [S0003-6951(00)00930-X].
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.411
Times cited: 44
DOI: 10.1063/1.127026
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“Electronic structure of Pd nanoparticles on carbon nanotubes”. Felten A, Ghijsen J, Pireaux J-J, Drube W, Johnson RL, Liang D, Hecq M, Van Tendeloo G, Bittencourt C, Micron 40, 74 (2009). http://doi.org/10.1016/j.micron.2008.01.013
Abstract: The effect of the oxygen plasma treatment on the electronic states of multi-wall carbon nanotubes (MWCNTs) is analyzed by X-ray photoemission measurements (XPS) and UPS, both using synchrotron radiation. It is found that the plasma treatment effectively grafts oxygen at the CNT-surface. Thereafter, the interaction between evaporated Pd and pristine or oxygen plasma-treated MWCNTs is investigated. Pd is found to nucleate at defective sites, whether initially present or introduced by oxygen plasma treatment. The plasma treatment induced a uniform dispersion of Pd clusters at the CNT-surface. The absence of additional features in the Pd 3d and C I s core levels spectra testifies that no Pd-C bond is formed. The shift of the Pd 3d core level towards high-binding energy for the smallest clusters is attributed to the Coulomb energy of the charged final state. (C) 2008 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.98
Times cited: 44
DOI: 10.1016/j.micron.2008.01.013
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“Growth and characterization of a-axis textured ZnO thin films”. Nistor LC, Ghica C, Matei D, Dinescu G, Dinescu M, Van Tendeloo G, Journal of crystal growth 277, 26 (2005). http://doi.org/10.1016/j.jcrysgro.2004.12.162
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.751
Times cited: 44
DOI: 10.1016/j.jcrysgro.2004.12.162
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“Linear reduction of stiffness and vibration frequencies in defected circular monolayer graphene”. Neek-Amal M, Peeters FM, Physical review : B : condensed matter and materials physics 81, 11 (2010). http://doi.org/10.1103/PhysRevB.81.235437
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 44
DOI: 10.1103/PhysRevB.81.235437
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“Mesoscopic field and current compensator based on a hybrid superconductor-ferromagnet structure”. Milošević, MV, Berdiyorov GR, Peeters FM, Physical review letters 95, 147004 (2005). http://doi.org/10.1103/PhysRevLett.95.147004
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 8.462
Times cited: 44
DOI: 10.1103/PhysRevLett.95.147004
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“Metallic nanoparticles on plasma treated carbon nanotubes : $Nano2hybrids$”. Bittencourt C, Felten A, Douhard B, Colomer J-F, Van Tendeloo G, Drube W, Ghijsen J, Pireaux J-J, Surface science : a journal devoted to the physics and chemistry of interfaces
T2 –, International Conference on NANO-Structures Self Assembling, JUL 02-06, 2006, Aix en Provence, FRANCE 601, 2800 (2007). http://doi.org/10.1016/j.susc.2006.12.045
Abstract: Multi-wall carbon nanotubes (MWCNTs) were decorated with metal clusters by thermal evaporation. Transmission electron microscopy (TEM) shows that the nature and extent of metal coverage can be varied by plasma treating the MWCNT surface. The metal clusters on oxygen plasma treated arc-discharge MWCNTs have a more dense distribution than the clusters evaporated on as-synthesized are-discharge MWCNTs. In contrast, the plasma treatment did not affect the cluster distribution on CVD MWCNTs. Analyses of the valence band and the core levels by X-ray photoelectron spectroscopy suggest poor charge transfer between gold clusters and MWCNTs; on the contrary suggest good charge transfer between Ni clusters and MWCNTs. (c) 2007 Elsevier B. V. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.062
Times cited: 44
DOI: 10.1016/j.susc.2006.12.045
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“Modeling of glow discharge optical emission spectrometry: calculation of the argon atomic optical emission spectrum”. Bogaerts A, Gijbels R, Vlcek J, Spectrochimica acta: part B : atomic spectroscopy 53, 1517 (1998). http://doi.org/10.1016/S0584-8547(98)00139-6
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.241
Times cited: 44
DOI: 10.1016/S0584-8547(98)00139-6
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“Structural and chemical effects on EELS L3,2 ionization edges in Ni-based intermetallic compounds”. Potapov PL, Kulkova SE, Schryvers D, Verbeeck J, Physical review : B : condensed matter and materials physics 64, 184110 (2001). http://doi.org/10.1103/PhysRevB.64.184110
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 44
DOI: 10.1103/PhysRevB.64.184110
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“Structural and dynamical aspects of small three-dimensional spherical Coulomb clusters”. Apolinario SWS, Partoens B, Peeters FM, New journal of physics 9, 283 (2007). http://doi.org/10.1088/1367-2630/9/8/283
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.786
Times cited: 44
DOI: 10.1088/1367-2630/9/8/283
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“Sn20.5-3.5As22I8: a largely disordered cationic clathrate with a new type of superstructure and abnormally low thermal conductivity”. Zaikina JV, Kovnir KA, Sobolev AV, Presniakov IA, Prots Y, Baitinger M, Schnelle W, Olenev AV, Lebedev OI, Van Tendeloo G, Grin Y, Shevelkov AV, Chemistry: a European journal 13, 5090 (2007). http://doi.org/10.1002/chem.200601772
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 5.317
Times cited: 44
DOI: 10.1002/chem.200601772
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“Thermally induced atomic reconstruction of PbSe/CdSe core/shell quantum dots into PbSe/CdSe bi-hemisphere hetero-nanocrystals”. Grodzinska D, Pietra F, van Huis MA, Vanmaekelbergh D, de Mello Donegá, C, Journal of materials chemistry 21, 11556 (2011). http://doi.org/10.1039/c0jm04458j
Abstract: The properties of hetero-nanocrystals (HNCs) depend strongly on the mutual arrangement of the nanoscale components. In this work we have investigated the structural and morphological evolution of colloidal PbSe/CdSe core/shell quantum dots upon annealing under vacuum. Prior to annealing the PbSe core has an approximately octahedral morphology with eight {111} facets, and the CdSe shell has zinc-blende crystal structure. Thermal annealing under vacuum at temperatures between 150 °C and 200 °C induces a structural and morphological reconstruction of the HNCs whereby the PbSe core and the CdSe shell are reorganized into two hemispheres joined by a common {111} Se plane. This thermally induced reconstruction leads to considerable changes in the optical properties of the colloidal PbSe/CdSe HNCs.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 44
DOI: 10.1039/c0jm04458j
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“Two-band superconductors : extended Ginzburg-Landau formalism by a systematic expansion in small deviation from the critical temperature”. Vagov A, Shanenko AA, Milošević, MV, Axt VM, Peeters FM, Physical review : B : condensed matter and materials physics 86, 144514 (2012). http://doi.org/10.1103/PhysRevB.86.144514
Abstract: We derive the extended Ginzburg-Landau (GL) formalism for a clean s-wave two-band superconductor by employing a systematic expansion of the free-energy functional and the corresponding matrix gap equation in powers of the small deviation from the critical temperature tau = 1 – T/T-c. The two lowest orders of this expansion produce the equation for T-c and the standard GL theory. It is shown that in agreement with previous studies, this two-band GL theory maps onto the single-band GL model and thus fails to describe the difference in the spatial profiles of the two-band condensates. We prove that this difference appears already in the leading correction to the standard GL theory, which constitutes the extended GL formalism. We derive linear differential equations that determine the leading corrections to the band order parameters and magnetic field, discuss the validity of these equations, and consider examples of an important interplay between the band condensates. Finally, we present numerical results for the thermodynamic critical magnetic field and temperature-dependent band gaps for recent materials of interest, which are in very good agreement with those obtained from the full BCS approach in a wide temperature range. To this end, we emphasize the advantages of our extended GL theory in comparison with the often used two-component GL-like model based on an unreconstructed two-band generalization of the Gor'kov derivation.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 44
DOI: 10.1103/PhysRevB.86.144514
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“Janus Gold Nanoparticles Obtained via Spontaneous Binary Polymer Shell Segregation”. Percebom AMM, Giner-casares JJ, Claes N, Bals S, Loh W, Liz-Marzan LM, Chemical communications 52, 4278 (2016). http://doi.org/10.1039/C5CC10454H
Abstract: Janus gold nanoparticles are of high interest because they allow directed self-assembly and display plasmonic properties. We succeeded in coating gold nanoparticles with two different polymers that form a Janus shell. The spontaneous segregation of two immiscible polymers at the surface of the nanoparticles was verified by NOESY NMR and most importantly by electron microscopy analysis in two and three dimensions. The Janus structure is additionally shown to affect the aggregation behavior of the nanoparticles.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 6.319
Times cited: 44
DOI: 10.1039/C5CC10454H
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“Electronic properties of triangular and hexagonal MoS2 quantum dots”. Pavlović, S, Peeters FM, Physical review : B : condensed matter and materials physics 91, 155410 (2015). http://doi.org/10.1103/PhysRevB.91.155410
Abstract: Using the tight-binding approach, we calculate the electronic structure of triangular and hexagonal MoS2 quantum dots. Due to the orbital asymmetry we show that it is possible to form quantum dots with the same shape but having different electronic properties. The electronic states of triangular and hexagonal quantum dots are explored, as well as the local and total density of states and the convergence towards the bulk spectrum with dot size is investigated. Our calculations show that: (1) edge states appear in the band gap, (2) that there are a larger number of electronic states in the conduction band as compared to the valence band, and (3) the relative number of edge states decreases with increasing dot size.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 44
DOI: 10.1103/PhysRevB.91.155410
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“Highly efficient rutile TiO2 photocatalysts with single Cu(II) and Fe(III) surface catalytic sites”. Neubert S, Mitoraj D, Shevlin SA, Pulisova P, Heimann M, Du Y, Goh GKL, Pacia M, Kruczała K, Turner S, Macyk W, Guo ZX, Hocking RK, Beranek R;, Journal of materials chemistry A : materials for energy and sustainability 4, 3127 (2016). http://doi.org/10.1039/c5ta07036h
Abstract: Highly active photocatalysts were obtained by impregnation of nanocrystalline rutile TiO2 powders with small amounts of Cu(II) and Fe(III) ions, resulting in the enhancement of initial rates of photocatalytic degradation of 4-chlorophenol in water by factors of 7 and 4, compared to pristine rutile, respectively. Detailed structural analysis by EPR and X-ray absorption spectroscopy (EXAFS) revealed that Cu(II) and Fe(III) are present as single species on the rutile surface. The mechanism of the photoactivity enhancement was elucidated by a combination of DFT calculations and detailed experimental mechanistic studies including photoluminescence measurements, photocatalytic experiments using scavengers, OH radical detection, and photopotential transient measurements. The results demonstrate that the single Cu(II) and Fe(III) ions act as effective cocatalytic sites, enhancing the charge separation, catalyzing “dark” redox reactions at the interface, thus improving the normally very low quantum yields of UV light-activated TiO2 photocatalysts. The exact mechanism of the photoactivity enhancement differs depending on the nature of the cocatalyst. Cu(II)-decorated samples exhibit fast transfer of photogenerated electrons to Cu(II/I) sites, followed by enhanced catalysis of dioxygen reduction, resulting in improved charge separation and higher photocatalytic degradation rates. At Fe(III)-modified rutile the rate of dioxygen reduction is not improved and the photocatalytic enhancement is attributed to higher production of highly oxidizing hydroxyl radicals produced by alternative oxygen reduction pathways opened by the presence of catalytic Fe(III/II) sites. Importantly, it was demonstrated that excessive heat treatment (at 450 degrees C) of photocatalysts leads to loss of activity due to migration of Cu(II) and Fe(III) ions from TiO2 surface to the bulk, accompanied by formation of oxygen vacancies. The demonstrated variety of mechanisms of photoactivity enhancement at single site catalyst-modified photocatalysts holds promise for developing further tailored photocatalysts for various applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 8.867
Times cited: 44
DOI: 10.1039/c5ta07036h
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“Dependence of the shape of graphene nanobubbles on trapped substance”. Ghorbanfekr-Kalashami H, Vasu KS, Nair RR, Peeters FM, Neek-Amal M, Nature communications 8, 15844 (2017). http://doi.org/10.1038/ncomms15844
Abstract: Van der Waals (vdW) interaction between two-dimensional crystals (2D) can trap substances in high pressurized (of order 1 GPa) on nanobubbles. Increasing the adhesion between the 2D crystals further enhances the pressure and can lead to a phase transition of the trapped material. We found that the shape of the nanobubble can depend critically on the properties of the trapped substance. In the absence of any residual strain in the top 2D crystal, flat nanobubbles can be formed by trapped long hydrocarbons (that is, hexadecane). For large nanobubbles with radius 130 nm, our atomic force microscopy measurements show nanobubbles filled with hydrocarbons (water) have a cylindrical symmetry (asymmetric) shape which is in good agreement with our molecular dynamics simulations. This study provides insights into the effects of the specific material and the vdW pressure on the microscopic details of graphene bubbles.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 12.124
Times cited: 44
DOI: 10.1038/ncomms15844
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“Atomically thin micas as proton-conducting membranes”. Mogg L, Hao G-P, Zhang S, Bacaksiz C, Zou Y, Haigh SJ, Peeters FM, Geim AK, Lozada-Hidalgo M, Nature nanotechnology 14, 962 (2019). http://doi.org/10.1038/S41565-019-0536-5
Abstract: Monolayers of graphene and hexagonal boron nitride (hBN) are highly permeable to thermal protons1,2. For thicker two-dimensional (2D) materials, proton conductivity diminishes exponentially, so that, for example, monolayer MoS2 that is just three atoms thick is completely impermeable to protons1. This seemed to suggest that only one-atom-thick crystals could be used as proton-conducting membranes. Here, we show that few-layer micas that are rather thick on the atomic scale become excellent proton conductors if native cations are ion-exchanged for protons. Their areal conductivity exceeds that of graphene and hBN by one to two orders of magnitude. Importantly, ion-exchanged 2D micas exhibit this high conductivity inside the infamous gap for proton-conducting materials3, which extends from ∼100 °C to 500 °C. Areal conductivity of proton-exchanged monolayer micas can reach above 100 S cm−2 at 500 °C, well above the current requirements for the industry roadmap4. We attribute the fast proton permeation to ~5-Å-wide tubular channels that perforate micas’ crystal structure, which, after ion exchange, contain only hydroxyl groups inside. Our work indicates that there could be other 2D crystals5 with similar nanometre-scale channels, which could help close the materials gap in proton-conducting applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 38.986
Times cited: 44
DOI: 10.1038/S41565-019-0536-5
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“Characterization of U/Pu particles originating from the nuclear weapon accidents at Palomares, Spain, 1966 and Thule, Greenland, 1968”. Lind OC, Salbu B, Janssens K, Proost K, Garcia-León M, Garcia-Tenorio R, The science of the total environment 376, 294 (2007). http://doi.org/10.1016/J.SCITOTENV.2006.11.050
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 4.9
Times cited: 44
DOI: 10.1016/J.SCITOTENV.2006.11.050
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“Quantitative trace element analysis of individual fly ash particles by means of X-ray microfluorescence”. Vincze L, Somogyi A, Osán J, Vekemans B, Török S, Janssens K, Adams F, Analytical chemistry 74, 1128 (2002). http://doi.org/10.1021/AC010789B
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 6.32
Times cited: 44
DOI: 10.1021/AC010789B
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“Alloy CsCdxPb1–xBr3Perovskite Nanocrystals: The Role of Surface Passivation in Preserving Composition and Blue Emission”. Imran M, Ramade J, Di Stasio F, De Franco M, Buha J, Van Aert S, Goldoni L, Lauciello S, Prato M, Infante I, Bals S, Manna L, Chemistry Of Materials 32, acs.chemmater.0c03825 (2020). http://doi.org/10.1021/acs.chemmater.0c03825
Abstract: Various strategies have been proposed to engineer the band gap of metal halide perovskite nanocrystals (NCs) while preserving their structure and composition and thus ensuring spectral stability of the emission color. An aspect that has only been marginally investigated is how the type of surface passivation influences the structural/color stability of AMX3 perovskite NCs composed of two different M2+ cations. Here, we report the synthesis of blue-emitting Cs-oleate capped CsCdxPb1–xBr3 NCs, which exhibit a cubic perovskite phase containing Cd-rich domains of Ruddlesden–Popper phases (RP phases). The RP domains spontaneously transform into pure orthorhombic perovskite ones upon NC aging, and the emission color of the NCs shifts from blue to green over days. On the other hand, postsynthesis ligand exchange with various Cs-carboxylate or ammonium bromide salts, right after NC synthesis, provides monocrystalline NCs with cubic phase, highlighting the metastability of RP domains. When NCs are treated with Cs-carboxylates (including Cs-oleate), most of the Cd2+ ions are expelled from NCs upon aging, and the NCs phase evolves from cubic to orthorhombic and their emission color changes from blue to green. Instead, when NCs are coated with ammonium bromides, the loss of Cd2+ ions is suppressed and the NCs tend to retain their blue emission (both in colloidal dispersions and in electroluminescent devices), as well as their cubic phase, over time. The improved compositional and structural stability in the latter cases is ascribed to the saturation of surface vacancies, which may act as channels for the expulsion of Cd2+ ions from NCs.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 8.6
Times cited: 44
DOI: 10.1021/acs.chemmater.0c03825
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