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“Efficiency of applying ammonium oxalate for protection of monumental limestone by poultice, immersion and brushing methods”. Mudronja D, Vanmeert F, Hellemans K, Fazinic S, Janssens K, Tibljas D, Rogosic M, Jakovljevic S, Applied physics A : materials science &, processing 111, 109 (2013). http://doi.org/10.1007/S00339-012-7365-9
Abstract: Samples of cretaceous limestone have been treated with three application methods (poultice, immersion and brushing) using different concentrations of ammonium oxalate solution (AmOx) and varying treatment time in order to test the efficiency of surface and in-depth formation of a protective layer of calcium oxalate (CaOx). Synchrotron-based microanalytical techniques (SR-mu XRD with 12.5 mu mx7.5 mu m (HxV) probe size, SR-mu FTIR with 10 mu mx10 mu m and 8 mu mx20 mu m probe sizes) and laboratory mu FTIR, XRD and SEM have been employed for analysis of the treated samples. Synchrotron-based techniques showed variations in the CaOx distribution along the surface on a micrometer scale. All treatments resulted in the development of a CaOx layer with a maximum thickness of approximately 40 mu m. Application by the brushing method with 10 1-min applications with 5-min breaks during one hour showed a development of the calcium oxalate layer equivalent to the poultice treatment taking 10 h. This treatment could be preferred for large marble or limestone surfaces where poultice usage is economically not feasible.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 1.455
Times cited: 13
DOI: 10.1007/S00339-012-7365-9
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“Scanning XRF investigation of a Flower Still Life and its underlying composition from the collection of the Kröller-Muller Museum”. Alfeld M, van der Snickt G, Vanmeert F, Janssens K, Dik J, Appel K, van der Loeff L, Chavannes M, Meedendorp T, Hendriks E, Applied physics A : materials science &, processing 111, 165 (2013). http://doi.org/10.1007/S00339-012-7526-X
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 1.455
Times cited: 35
DOI: 10.1007/S00339-012-7526-X
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“Visualizing the 17th century underpainting in Portrait of an Old Man by Rembrandt van Rijn using synchrotron-based scanning macro-XRF”. Alfeld M, Siddons DP, Janssens K, Dik J, Woll A, Kirkham R, van de Wetering E, Applied physics A : materials science &, processing 111, 157 (2013). http://doi.org/10.1007/S00339-012-7490-5
Abstract: In 17th century Old Master Paintings, the underpainting generally refers to the first sketch of a composition. The underpainting is applied to a prepared ground using a monochrome, brown oil paint to roughly indicate light, shade and contours. So far, methods to visualize the underpainting-other than in localized cross-sections-have been very limited. Neither infrared reflectography nor neutron induced autoradiography have proven to be practical, adequate visualization tools. Thus, although of fundamental interest in the understanding of a painting's genesis, the underpainting has virtually escaped all imaging efforts. In this contribution we will show that 17th century underpainting may consist of a highly heterogeneous mixture of pigments, including copper pigments. We suggest that this brown pigment mixture is actually the recycled left-over of a palette scraping. With copper as the heaviest exclusive elemental component, we will hence show in a case study on a Portrait of an Old Man attributed to Rembrandt van Rijn how scanning macro-XRF can be used to efficiently visualize the underpainting below the surface painting and how this information can contribute to the discussion of the painting's authenticity.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 1.455
Times cited: 26
DOI: 10.1007/S00339-012-7490-5
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“Ciliary white light : optical aspect of ultrashort laser ablation on transparent dielectrics”. Liu Y, Brelet Y, He Z, Yu L, Mitryukovskiy S, Houard A, Forestier B, Couairon A, Mysyrowicz A, Physical review letters 110, 097601 (2013). http://doi.org/10.1103/PhysRevLett.110.097601
Abstract: We report on a novel nonlinear optical phenomenon, coined as ciliary white light, during laser ablation of transparent dielectrics. It is observed in 14 different transparent materials including glasses, crystals, and polymers. This phenomenon is also universal with respect to laser polarization, pulse duration, and focusing geometry. We interpret its formation in terms of the nonlinear diffraction of the laser generated white light by the ablation crater covered by nanostructures. It carries rich information on the damage profile and morphology dynamics of the ablated surface, providing a real time in situ observation of the laser ablation process. DOI: 10.1103/PhysRevLett.110.097601
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 8.462
Times cited: 10
DOI: 10.1103/PhysRevLett.110.097601
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“Comment on “Quantized orbital angular momentum transfer and magnetic dichroism in the interaction of electron vortices with matter””. Schattschneider P, Löffler S, Verbeeck J, Physical review letters 110, 189501 (2013). http://doi.org/10.1103/PhysRevLett.110.189501
Keywords: Editorial; Electron microscopy for materials research (EMAT)
Impact Factor: 8.462
Times cited: 8
DOI: 10.1103/PhysRevLett.110.189501
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“Defect healing and enhanced nucleation of carbon nanotubes by low-energy ion bombardment”. Neyts EC, Ostrikov K, Han ZJ, Kumar S, van Duin ACT, Bogaerts A, Physical review letters 110, 065501 (2013). http://doi.org/10.1103/PhysRevLett.110.065501
Abstract: Structural defects inevitably appear during the nucleation event that determines the structure and properties of single-walled carbon nanotubes. By combining ion bombardment experiments with atomistic simulations we reveal that ion bombardment in a suitable energy range allows these defects to be healed resulting in an enhanced nucleation of the carbon nanotube cap. The enhanced growth of the nanotube cap is explained by a nonthermal ion-induced graphene network restructuring mechanism.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 8.462
Times cited: 50
DOI: 10.1103/PhysRevLett.110.065501
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“Observation of the Larmor and Gouy rotations with electron vortex beams”. Guzzinati G, Schattschneider P, Bliokh KY, Nori F, Verbeeck J, Physical review letters 110, 093601 (2013). http://doi.org/10.1103/PhysRevLett.110.093601
Abstract: Electron vortex beams carrying intrinsic orbital angular momentum (OAM) are produced in electron microscopes where they are controlled and focused by using magnetic lenses. We observe various rotational phenomena arising from the interaction between the OAM and magnetic lenses. First, the Zeeman coupling, proportional to the OAM and magnetic field strength, produces an OAM-independent Larmor rotation of a mode superposition inside the lens. Second, when passing through the focal plane, the electron beam acquires an additional Gouy phase dependent on the absolute value of the OAM. This brings about the Gouy rotation of the superposition image proportional to the sign of the OAM. A combination of the Larmor and Gouy effects can result in the addition (or subtraction) of rotations, depending on the OAM sign. This behavior is unique to electron vortex beams and has no optical counterpart, as Larmor rotation occurs only for charged particles. Our experimental results are in agreement with recent theoretical predictions.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 8.462
Times cited: 91
DOI: 10.1103/PhysRevLett.110.093601
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“Origin of magnetism and quasiparticles properties in Cr-doped TiO2”. da Pieve F, Di Matteo S, Rangel T, Giantomassi M, Lamoen D, Rignanese G-M, Gonze X, Physical review letters 110, 136402 (2013). http://doi.org/10.1103/PhysRevLett.110.136402
Abstract: Combining the local spin density approximation (LSDA)+U and an analysis of superexchange interactions beyond density functional theory, we describe the magnetic ground state of Cr-doped TiO2, an intensively studied and debated dilute magnetic oxide. In parallel, we correct our LSDA+U (+ superexchange) ground state through GW corrections (GW@LSDA+U) that reproduce the position of the impurity states and the band gaps in satisfying agreement with experiments. Because of the different topological coordinations of Cr-Cr bonds in the ground states of rutile and anatase, superexchange interactions induce either ferromagnetic or antiferromagnetic couplings of Cr ions. In Cr-doped anatase, this interaction leads to a new mechanism which stabilizes a (nonrobust) ferromagnetic ground state, in keeping with experimental evidence, without the need to invoke F-center exchange. The interplay between structural defects and vacancies in contributing to the superexchange is also unveiled.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 8.462
Times cited: 15
DOI: 10.1103/PhysRevLett.110.136402
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“Self-propelled Janus particles in a ratchet : numerical simulations”. Ghosh PK, Misko VR, Marchesoni F, Nori F, Physical review letters 110, 1 (2013). http://doi.org/10.1103/PhysRevLett.110.268301
Abstract: Brownian transport of self-propelled overdamped microswimmers (like Janus particles) in a two-dimensional periodically compartmentalized channel is numerically investigated for different compartment geometries, boundary collisional dynamics, and particle rotational diffusion. The resulting time-correlated active Brownian motion is subject to rectification in the presence of spatial asymmetry. We prove that ratcheting of Janus particles can be orders of magnitude stronger than for ordinary thermal potential ratchets and thus experimentally accessible. In particular, autonomous pumping of a large mixture of passive particles can be induced by just adding a small fraction of Janus particles.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 8.462
Times cited: 143
DOI: 10.1103/PhysRevLett.110.268301
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“Air quality monitoring in a museum for preventive conservation : results of a three-year study in the Plantin-Moretus Museum in Antwerp, Belgium”. Krupińska B, Van Grieken R, De Wael K, Microchemical journal 110, 350 (2013). http://doi.org/10.1016/J.MICROC.2013.05.006
Abstract: Through different research projects on air quality in museums, researcher and conservators try identifying various risks of air pollution on materials. The conclusions may be later translated into specific actions for a maximum preservation of the museum collections, a process known as preventive conservation. Air pollution is a particular problem in historical buildings such as museums, because they were not originally built to exhibit and protect art objects in a sustainable way. This article reports on the data and results that were obtained during 10 sampling campaigns, in the period between November 2008 and February 2012 in a museum in Antwerp (Belgium), i.e. Plantin-Moretus Museum/Print Room. Different pollutants were measured inside and outside the museum such as inorganic gases, particulate matter and black carbon. The report specifically addresses environmental factors that may be responsible for damage to the collections present in museums. Thanks to the knowledge about the current situation in the museum, accurate solutions regarding preventive conservation, in general, are suggested.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.034
Times cited: 46
DOI: 10.1016/J.MICROC.2013.05.006
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“The wear of polished and glazed zirconia against enamel”. Janyavula S, Lawson N, Çakir D, Beck P, Ramp LC, Burgess JO, Journal Of Prosthetic Dentistry 109, 22 (2013). http://doi.org/10.1016/S0022-3913(13)60005-0
Abstract: Statement of problem. The wear of tooth structure opposing anatomically contoured zirconia crowns requires further investigation. Purpose. The purpose of this in vitro study was to measure the roughness and wear of polished, glazed, and polished then reglazed zirconia against human enamel antagonists and compare the measurements to those of veneering porcelain and natural enamel. Material and methods. Zirconia specimens were divided into polished, glazed, and polished then reglazed groups (n=8). A veneering porcelain (Ceramco3) and enamel were used as controls. The surface roughness of all pretest specimens was measured. Wear testing was performed in the newly designed Alabama wear testing device. The mesiobuccal cusps of extracted molars were standardized and used as antagonists. Three-dimensional (3D) scans of the specimens and antagonists were obtained at baseline and after 200 000 and 400 000 cycles with a profilometer. The baseline scans were superimposed on the posttesting scans to determine volumetric wear. Data were analyzed with a 1-way ANOVA and Tukey Honestly Significant Difference (HSD) post hoc tests (alpha=.05) Results. Surface roughness ranked in order of least rough to roughest was: polished zirconia, glazed zirconia, polished then reglazed zirconia, veneering porcelain, and enamel. For ceramic, there was no measureable loss on polished zirconia, moderate loss on the surface of enamel, and significant loss on glazed and polished then reglazed zirconia. The highest ceramic wear was exhibited by the veneering ceramic. For enamel antagonists, polished zirconia caused the least wear, and enamel caused moderate wear. Glazed and polished then reglazed zirconia showed significant opposing enamel wear, and veneering porcelain demonstrated the most. Conclusions. Within the limitations of the study, polished zirconia is wear-friendly to the opposing tooth. Glazed zirconia causes more material and antagonist wear than polished zirconia. The surface roughness of the zirconia aided in predicting the wear of the opposing dentition. (J Prosthet Dent 2013;109:22-29)
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.095
Times cited: 89
DOI: 10.1016/S0022-3913(13)60005-0
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“Microchemical investigation of bone derived from mice treated with strontium in different chemical forms using scanning electron microscopy and micro-Raman spectroscopy”. Jabłoński MB, Stefaniak EA, Darchuk L, Turzańska K, Gorzelak M, Kuduk R, Dorriné, W, Van Grieken R, Microchemical journal 108, 168 (2013). http://doi.org/10.1016/J.MICROC.2012.10.015
Abstract: We used SEM/EDX and micro-Raman spectroscopy to investigate the chemical changes (both on the level of elementary and molecular composition) of mice bones when strontium is incorporated in their microstructure after being administered in the form of two salts: chloride and ranelate. Strontium accumulated mainly in vicinity of bone edges, both cortical and close to bone marrow. The distribution of other elements comprising bone samples (Ca, P, Mg, K etc.) was also determined by energy-dispersive X-ray analysis (EDX). The area adjacent to a cortical bone edge with accumulated strontium has presented modified Raman spectral profiles. Besides most of the Raman bands typical for both mineral (hydroxyapatite with carbonate substitution type B) and organic phases of a bone, we observed a Raman band at 811 cm− 1. It was detected regularly in the sample with high strontium concentration.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/J.MICROC.2012.10.015
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“Towards CMOS-compatible single-walled carbon nanotube resonators”. Pathangi H, Cherman V, Khaled A, Sorée B, Groeseneken G, Witvrouw A, Microelectronic engineering 107, 219 (2013). http://doi.org/10.1016/j.mee.2012.06.007
Abstract: We report a totally CMOS-compatible fabrication technique to assemble horizontally suspended single-walled carbon nanotube (SWCNT) resonators. Individual SWCNTs are assembled in parallel at multiple sites by a technique called dielectrophoresis. The mechanical resonance frequencies of the suspended SWCNTs are in the range of 2035 MHz as determined from the piezoresistive response of the resonators during electrostatic actuation. The resistance of the suspended SWCNT either remains unchanged or increases or decreases significantly as a function of the actuation frequency. This can be explained by the effect the nanotube chirality has on the piezoresistive gauge factor.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 1.806
Times cited: 6
DOI: 10.1016/j.mee.2012.06.007
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“Stable carbon isotopic ratio measurement of polycyclic aromatic hydrocarbons as a tool for source identification and apportionment : a review of analytical methodologies”. Buczyńska AJ, Geypens B, Van Grieken R, De Wael K, Talanta : the international journal of pure and applied analytical chemistry 105, 435 (2013). http://doi.org/10.1016/J.TALANTA.2012.10.075
Abstract: The measurement of the ratio of stable isotopes of carbon (13C/12C expressed as a δ13C) in the individual components of a sample may be used as a means to identify the origin of these components. This article reviews the approaches and reports on the successes and failures of source identification and apportionment of Polycyclic Aromatic Hydrocarbons (PAHs) with the use of compound-specific isotope analysis (CSIA). One of the conditions for a precise and accurate analysis of isotope ratios with the use of GC-C-IRMS is the need for well separated peaks, with no co-elutions, and reduced unresolved complex mixture (UCM). Additionally, special care needs to be taken for an investigation of possible isotope fractionation effects introduced during the analytical treatment of samples. With the above-mentioned problems in mind, this review discusses in detail and compares current laboratory methodologies, mainly in the extraction and subsequent clean-up techniques used for environmental samples (air particulate matter, soil and sediments). Sampling strategies, the use of isotopic internal standards and the ranges for precision and accuracy are also reported and discussed.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 4.162
Times cited: 19
DOI: 10.1016/J.TALANTA.2012.10.075
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“A techno-economic evaluation of a biomass energy conversion park”. Van Dael M, Van Passel S, Pelkmans L, Guisson R, Reumermann P, Luzardo NM, Witters N, Broeze J, Applied Energy 104, 611 (2013). http://doi.org/10.1016/J.APENERGY.2012.11.071
Abstract: Biomass as a renewable energy source has many advantages and is therefore recognized as one of the main renewable energy sources to be deployed in order to attain the target of 20% renewable energy use of final energy consumption by 2020 in Europe. In this paper the concept of a biomass Energy Conversion Park (ECP) is introduced. A biomass ECP can be defined as a synergetic, multi-dimensional biomass conversion site with a highly integrated set of conversion technologies in which a multitude of regionally available biomass (residue) sources are converted into energy and materials. A techno-economic assessment is performed on a case study in the Netherlands to illustrate the concept and to comparatively assess the highly integrated system with two mono-dimensional models. The three evaluated models consist of (1) digestion of the organic fraction of municipal solid waste, (2) co-digestion of manure and co-substrates, and (3) integration. From a socio-economic point of view it can be concluded that it is economically and energetically more interesting to invest in the integrated model than in two separate models. The integration is economically feasible and environmental benefits can be realized. For example, the integrated model allows the implementation of a co-digester. Unmanaged manure would otherwise represent a constant pollution risk. However, from an investor's standpoint one should firstly invest in the municipal solid waste digester since the net present value (NPV) of this mono-dimensional model is higher than that of the multi-dimensional model. A sensitivity analysis is performed to identify the most influencing parameters. Our results are of interest for companies involved in the conversion of biomass. The conclusions are useful for policy makers when deciding on policy instruments concerning manure processing or biogas production. (C) 2012 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Engineering Management (ENM)
Impact Factor: 7.182
Times cited: 45
DOI: 10.1016/J.APENERGY.2012.11.071
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“Local bond length variations in boron-doped nanocrystalline diamond measured by spatially resolved electron energy-loss spectroscopy”. Lu Y-G, Turner S, Verbeeck J, Janssens SD, Haenen K, Van Tendeloo G, Applied physics letters 103, 032105 (2013). http://doi.org/10.1063/1.4813842
Abstract: Variations in local bond length and coordination in boron-doped nanocrystalline diamond (NCD) films have been studied through changes in the fine structure of boron and carbon K-edges in electron energy-loss spectra, acquired in a scanning transmission electron microscope. The presence of high concentrations of B in pristine diamond regions and enrichment of B at defects in single NCD grains is demonstrated. Local bond length variations are evidenced through an energy shift of the carbon 1s → σ* edge at B-rich defective regions within single diamond grains, indicating an expansion of the diamond bond length at sites with local high B content.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.411
Times cited: 15
DOI: 10.1063/1.4813842
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“Modeling ultrashort laser-induced emission from a negatively biased metal”. Wendelen W, Mueller BY, Autrique D, Bogaerts A, Rethfeld B, Applied physics letters 103, 221603 (2013). http://doi.org/10.1063/1.4830378
Abstract: A theoretical study of ultrashort laser-induced electron emission from a negatively biased metallic cathode has been performed. Classical as well as tunneling electron emission mechanisms are considered. It was found that electron emission is governed by an interplay of processes inside as well as above the cathode. A hybrid model is proposed, where the electron distribution within the target is retrieved from Boltzmann scattering integrals, while the charge distribution above it is studied by a Particle-In-Cell simulation. The results indicate that non-equilibrium effects determine the initial emission process, whereas the space charge above the target suppresses the effectively emitted charge.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.411
Times cited: 8
DOI: 10.1063/1.4830378
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“Realization of free-standing silicene using bilayer graphene”. Neek-Amal M, Sadeghi A, Berdiyorov GR, Peeters FM, Applied physics letters 103, 261904 (2013). http://doi.org/10.1063/1.4852636
Abstract: The available synthesized silicene-like structures have been only realized on metallic substrates which are very different from the standalone buckled silicene, e. g., the Dirac cone of silicene is destroyed due to lattice distortion and the interaction with the substrate. Using graphene bilayer as a scaffold, a route is proposed to synthesize silicene with electronic properties decoupled from the substrate. The buckled hexagonal arrangement of silicene between the graphene layers is found to be very similar to the theoretically predicted standalone buckled silicene which is only very weakly van der Waals coupled to the graphene layers with a graphite-like interlayer distance of 3.42 angstrom and without any lattice distortion. We found that these stacked layers are stable well above room temperature. (C) 2013 AIP Publishing LLC.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 74
DOI: 10.1063/1.4852636
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“Revisiting the interplay between ablation, collisional, and radiative processes during ns-laser ablation”. Autrique D, Gornushkin I, Alexiades V, Chen Z, Bogaerts A, Rethfeld B, Applied physics letters 103, 174102 (2013). http://doi.org/10.1063/1.4826505
Abstract: A study of ns-laser ablation is presented, which focuses on the transient behavior of the physical processes that act in and above a copper sample. A dimensionless multiphase collisional radiative model describes the interplay between the ablation, collisional, and radiative mechanisms. Calculations are done for a 6 ns-Nd:YAG laser pulse operating at 532 nm and fluences up to 15 J/cm2. Temporal intensity profiles as well as transmissivities are in good agreement with experimental results. It is found that volumetric ablation mechanisms and photo-processes both play an essential role in the onset of ns-laser induced breakdown.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.411
Times cited: 13
DOI: 10.1063/1.4826505
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“Spectroscopy of snake states using a graphene Hall bar”. Milovanović, SP, Masir MR, Peeters FM, Applied physics letters 103, 233502 (2013). http://doi.org/10.1063/1.4838557
Abstract: An approach to observe snake states in a graphene Hall bar containing a pn-junction is proposed. The magnetic field dependence of the bend resistance in a ballistic graphene Hall bar structure containing a tilted pn-junction oscillates as a function of applied magnetic field. We show that each oscillation is due to a specific snake state that moves along the pn-interface. Furthermore, depending on the value of the magnetic field and applied potential, we can control the lead in which the electrons will end up and hence control the response of the system.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 15
DOI: 10.1063/1.4838557
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“Tunable double Dirac cone spectrum in bilayer \alpha-graphyne”. Leenaerts O, Partoens B, Peeters FM, Applied physics letters 103, 013105 (2013). http://doi.org/10.1063/1.4812977
Abstract: Monolayer alpha-graphyne was recently proposed as a new all-carbon material having an electronic spectrum consisting of Dirac cones. Based on a first-principles investigation of bilayer alpha-graphyne, we show that the electronic band structure is qualitatively different from its monolayer form and depends crucially on the stacking mode of the two layers. Two stable stacking modes are found: a configuration with a gapless parabolic band structure, similar to AB stacked bilayer graphene, and another one which exhibits a doubled Dirac-cone spectrum. The latter can be tuned by an electric field with a gap opening rate of 0.3 eA. (C) 2013 AIP Publishing LLC.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 58
DOI: 10.1063/1.4812977
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“Attenuation of superconductivity in manganite/cuprate heterostructures by epitaxially induced CuO intergrowths”. H Zhang N Gauquelin GA Botton and JYT Wei, Applied Physics Letters 103, 052606 (2013). http://doi.org/10.1063/1.4813840
Abstract: We examine the effect of CuO intergrowths on the superconductivity in epitaxial
La 2/3 Ca 1/3 MnO 3 / YBa 2 Cu 3 O 7−δ La2/3Ca1/3MnO3/YBa2Cu3O7−δ
(LCMO/YBCO) thin-film heterostructures. Scanning transmission electron microscopy on bilayer LCMO/YBCO thin films revealed double CuO-chain intergrowths which form regions with the 247 lattice structure in the YBCO layer. These nanoscale 247 regions do not appear in x-ray diffraction, but can physically account for the reduced critical temperature (Tc) of bilayer thin films relative to unilayer films with the same YBCO thickness, at least down to ∼25 nm. We attribute the CuO intergrowths to the bilayer heteroepitaxial mismatch and the Tc reduction to the generally lower Tc seen in bulk 247 samples. These epitaxially-induced CuO intergrowths provide a microstructural mechanism for the attenuation of superconductivity in LCMO/YBCO heterostructures.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Times cited: 12
DOI: 10.1063/1.4813840
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“Ti4O7 supported Ru@Pt core–shell catalyst for CO-tolerance in PEM fuel cell hydrogen oxidation reaction”. L Zhang J Kim J Zhang F Nan N Gauquelin GA Botton P He R Bashyam S Knights, Applied Energy 103, 507 (2013). http://doi.org/10.1016/j.apenergy.2012.10.017
Abstract: A new method is developed for synthesizing Ti4O7 supported Ru@Pt core–shell catalyst (Ru@Pt/Ti4O7) through pyrolysis followed by microwave irradiation. The purpose is to improve the Ru durability of PtRu from core–shell structure and strong bonding to Ti4O7 oxide. In this method, the first step is to co-reduce the mixture of ruthenium precursor and TiO2 in a H2 reducing atmosphere under heat-treatment to obtain a Ru core on Ti4O7 support, and the second step is to create a shell of platinum via microwave irradiation. Energy dispersive X-ray spectrometry, X-ray Diffraction, High-resolution Scanning Transmission Electron Microscopy with the high-angle annular dark-field method and Electron Energy-Loss Spectroscopy are used to demonstrate that this catalyst with larger particles has a core–shell structure with a Ru core and a Pt shell. Electrochemical measurements show Ru@Pt/Ti4O7 catalyst has a higher CO-tolerance capability than that of PtRu/C alloy catalyst.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Times cited: 33
DOI: 10.1016/j.apenergy.2012.10.017
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“Towards rapid nanoscale measurement of strain in III-nitride heterostructures”. Jones E, Cooper D, Rouvière J-L, Béché, A, Azize M, Palacios T, Gradecak S, Applied Physics Letters 103, 231904 (2013). http://doi.org/10.1063/1.4838617
Abstract: We report the structural and compositional nanoscale characterization of InAlN/GaN nanoribbon-structured high electron mobility transistors (HEMTs) through the use of geometric phase analysis (GPA) and nanobeam electron diffraction (NBED). The strain distribution in the HEMT layer is quantified and compared to the expected strain profile for the nominal structure predicted by finite element analysis (FEA). Using the experimental strain results, the actual structure is determined and used to modify the FEA model. The improved fit of the model demonstrates that GPA and NBED provide a powerful platform for routine and rapid characterization of strain in III-V semiconducting device systems leading to insights into device evolution during processing and future device optimization.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.411
Times cited: 6
DOI: 10.1063/1.4838617
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“Improved strain precision with high spatial resolution using nanobeam precession electron diffraction”. Rouvière J-L, Béché, A, Martin Y, Denneulin T, Cooper D, Applied physics letters 103, 241913 (2013). http://doi.org/10.1063/1.4829154
Abstract: NanoBeam Electron Diffraction is a simple and efficient technique to measure strain in nanostructures. Here, we show that improved results can be obtained by precessing the electron beam while maintaining a few nanometer probe size, i.e., by doing Nanobeam Precession Electron Diffraction (N-PED). The precession of the beam makes the diffraction spots more uniform and numerous, making N-PED more robust and precise. In N-PED, smaller probe size and better precision are achieved by having diffraction disks instead of diffraction dots. Precision in the strain measurement better than 2 × 10−4 is obtained with a probe size approaching 1 nm in diameter.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.411
Times cited: 53
DOI: 10.1063/1.4829154
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“Atomic scale investigation of a PbTiO3/SrRuO3/DyScO3 heterostructure”. Egoavil R, Tan H, Verbeeck J, Bals S, Smith B, Kuiper B, Rijnders G, Koster G, Van Tendeloo G, Applied physics letters 102, 223106 (2013). http://doi.org/10.1063/1.4809597
Abstract: An epitaxial PbTiO3 thin film grown on self-organized crystalline SrRuO3 nanowires deposited on a DyScO3 substrate with ordered DyO and ScO2 chemical terminations is investigated by transmission electron microscopy. In this PbTiO3/SrRuO3/DyScO3 heterostructure, the SrRuO3 nanowires are assumed to grow on only one type of substrate termination. Here, we report on the structure, morphology, and chemical composition analysis of this heterostructure. Electron energy loss spectroscopy reveals the exact termination sequence in this complex structure. The energy loss near-edge structure of the Ti-L-2,L-3, Sc-L-2,L-3, and O K edges shows intrinsic interfacial electronic reconstruction. Furthermore, PbTiO3 domain walls are observed to start at the end of the nanowires resulting in atomic steps on the film surface. (C) 2013 AIP Publishing LLC.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.411
Times cited: 12
DOI: 10.1063/1.4809597
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“Cerenkov emission of terahertz acoustic-phonons from graphene”. Zhao CX, Xu W, Peeters FM, Applied physics letters 102, 222101 (2013). http://doi.org/10.1063/1.4808392
Abstract: We present a theoretical study of the electrical generation of acoustic-phonon emission from graphene at room temperature. The drift velocity (v(x)) and temperature of electrons driven by dc electric field (F-x) are determined by solving self-consistently the momentum-and energy-balance equations derived from the Boltzmann equation. We find that in the presence of impurity, acoustic-and optic-phonon scattering, v(x) can be much larger than the longitudinal (v(l)) and transverse (v(t)) sound velocities in graphene even within the linear response regime. As a result, although the acoustic Cerenkov effect cannot be obviously seen in the analytical formulas, the enhanced acoustic-phonon emission can be observed with increasing F-x when v(x) > v(l) and v > v(t). The frequency of acoustic-phonon emission from graphene can be above 10 THz, which is much higher than that generated from conventional semiconductor systems. This study is pertinent to the application of graphene as hypersonic devices such as terahertz sound sources. (C) 2013 AIP Publishing LLC.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 25
DOI: 10.1063/1.4808392
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“Figure of merit for and identification of sub-60 mV/decade devices”. Vandenberghe WG, Verhulst AS, Sorée B, Magnus W, Groeseneken G, Smets Q, Heyns M, Fischetti MV, Applied physics letters 102, 013510 (2013). http://doi.org/10.1063/1.4773521
Abstract: A figure of merit I60 is proposed for sub-60 mV/decade devices as the highest current where the input characteristics exhibit a transition from sub- to super-60 mV/decade behavior. For sub-60 mV/decade devices to be competitive with metal-oxide-semiconductor field-effect devices, I60 has to be in the 1-10 μA/μm range. The best experimental tunnel field-effect transistors (TFETs) in the literature only have an I60 of 6×10-3 μA/μm but using theoretical simulations, we show that an I60 of up to 10 μA/μm should be attainable. It is proven that the Schottky barrier FET (SBFET) has a 60 mV/decade subthreshold swing limit while combining a SBFET and a TFET does improve performance.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 64
DOI: 10.1063/1.4773521
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“High resolution transmission electron microscopy characterization of fcc ->, 9R transformation in nanocrystalline palladium films due to hydriding”. Amin-Ahmadi B, Idrissi H, Delmelle R, Pardoen T, Proost J, Schryvers D, Applied physics letters 102, 071911 (2013). http://doi.org/10.1063/1.4793512
Abstract: Sputtered nanocrystalline palladium thin films with nanoscale growth twins have been subjected to hydriding cycles. The evolution of the twin boundaries has been investigated using high resolution transmission electron microscopy. Surprisingly, the Sigma 3{112} incoherent twin boundaries dissociate after hydriding into two phase boundaries bounding a 9R phase. This phase which corresponds to single stacking faults located every three {111} planes in the fcc Pd structure was not expected because of the high stacking fault energy of Pd. This observation is connected to the influence of the Hydrogen on the stacking fault energy of palladium and the high compressive stresses building up during hydriding. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4793512]
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.411
Times cited: 14
DOI: 10.1063/1.4793512
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“Klein paradox for a pn junction in multilayer graphene”. Van Duppen B, Peeters FM, Europhysics letters 102, 27001 (2013). http://doi.org/10.1209/0295-5075/102/27001
Abstract: Charge carriers in single and multilayered graphene systems behave as chiral particles due to the particular lattice symmetry of the crystal. We show that the interplay between the meta-material properties of graphene multilayers and the pseudospinorial properties of the charge carriers result in the occurrence of Klein and anti-Klein tunneling for rhombohedral stacked multilayers. We derive an algebraic formula predicting the angles at which these phenomena occur and support this with numerical calculations for systems up to four layers. We present a decomposition of an arbitrarily stacked multilayer into pseudospin doublets that have the same properties as rhombohedral systems with a lower number of layers. Copyright (C) EPLA, 2013
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.957
Times cited: 17
DOI: 10.1209/0295-5075/102/27001
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