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“Adaptively time stepping the stochastic Landau-Lifshitz-Gilbert equation at nonzero temperature: Implementation and validation in MuMax3”. Leliaert J, Mulkers J, De Clercq J, Coene A, Dvornik M, Van Waeyenberge B, AIP advances 7, 125010 (2017). http://doi.org/10.1063/1.5003957
Abstract: Thermal fluctuations play an increasingly important role in micromagnetic research relevant for various biomedical and other technological applications. Until now, it was deemed necessary to use a time stepping algorithm with a fixed time step in order to perform micromagnetic simulations at nonzero temperatures. However, Berkov and Gorn have shown in [D. Berkov and N. Gorn, J. Phys.: Condens. Matter,14, L281, 2002] that the drift term which generally appears when solving stochastic differential equations can only influence the length of the magnetization. This quantity is however fixed in the case of the stochastic Landau-Lifshitz-Gilbert equation. In this paper, we exploit this fact to straightforwardly extend existing high order solvers with an adaptive time stepping algorithm. We implemented the presented methods in the freely available GPU-accelerated micromagnetic software package MuMax3 and used it to extensively validate the presented methods. Next to the advantage of having control over the error tolerance, we report a twenty fold speedup without a loss of accuracy, when using the presented methods as compared to the hereto best practice of using Heun’s solver with a small fixed time step.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 1.568
Times cited: 13
DOI: 10.1063/1.5003957
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“Nonlinear light mixing by graphene plasmons”. Kundys D, Van Duppen B, Marshall OP, Rodriguez F, Torre I, Tomadin A, Polini M, Grigorenko AN, Nano letters 18, 282 (2018). http://doi.org/10.1021/ACS.NANOLETT.7B04114
Abstract: <script type='text/javascript'>document.write(unpmarked('Graphene is known to possess strong optical nonlinearity which turned out to be suitable for creation of efficient saturable absorbers in mode locked fiber lasers. Nonlinear response of graphene can be further enhanced by the presence of graphene plasmons. Here, we report a novel nonlinear effect observed in nanostructured graphene which comes about due to excitation of graphene plasmons. We experimentally detect and theoretically explain enhanced mixing of near-infrared and mid-infrared light in arrays of graphene nanoribbons. Strong compression of light by graphene plasmons implies that the described effect of light mixing is nonlocal in nature and orders of magnitude larger than the conventional local graphene nonlinearity. Both second and third order nonlinear effects were observed in our experiments with the recalculated third-order nonlinearity coefficient reaching values of 4.5 x 10(-6) esu. The suggested effect could be used in variety of applications including nonlinear light modulators, light multiplexers, light logic, and sensing devices.'));
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 12.712
Times cited: 12
DOI: 10.1021/ACS.NANOLETT.7B04114
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“Exploring the Optical and Morphological Properties of Ag and Ag/TiO2 Nanocomposites Grown by Supersonic Cluster Beam Deposition”. Cavaliere E, Benetti G, Van Bael M, Winckelmans N, Bals S, Gavioli L, Nanomaterials 7, 442 (2017). http://doi.org/10.3390/nano7120442
Abstract: Nanocomposite systems and nanoparticle (NP) films are crucial for many applications and research fields. The structure-properties correlation raises complex questions due to the collective structure of these systems, often granular and porous, a crucial factor impacting their effectiveness and performance. In this framework, we investigate the optical and morphological properties of Ag nanoparticles (NPs) films and of Ag NPs/TiO₂ porous matrix films, one-step grown by supersonic cluster beam deposition. Morphology and structure of the Ag NPs film and of the Ag/TiO₂ (Ag/Ti 50-50) nanocomposite are related to the optical properties of the film employing spectroscopic ellipsometry (SE). We employ a simple Bruggeman effective medium approximation model, corrected by finite size effects of the nano-objects in the film structure to gather information on the structure and morphology of the nanocomposites, in particular porosity and average NPs size for the Ag/TiO₂ NP film. Our results suggest that SE is a simple, quick and effective method to measure porosity of nanoscale films and systems, where standard methods for measuring pore sizes might not be applicable.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.553
Times cited: 19
DOI: 10.3390/nano7120442
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“Proposal for nanoscale cascaded plasmonic majority gates for non-Boolean computation”. Dutta S, Zografos O, Gurunarayanan S, Radu I, Sorée B, Catthoor F, Naeemi A, Scientific reports 7, 17866 (2017). http://doi.org/10.1038/S41598-017-17954-2
Abstract: <script type='text/javascript'>document.write(unpmarked('Surface-plasmon-polariton waves propagating at the interface between a metal and a dielectric, hold the key to future high-bandwidth, dense on-chip integrated logic circuits overcoming the diffraction limitation of photonics. While recent advances in plasmonic logic have witnessed the demonstration of basic and universal logic gates, these CMOS oriented digital logic gates cannot fully utilize the expressive power of this novel technology. Here, we aim at unraveling the true potential of plasmonics by exploiting an enhanced native functionality – the majority voter. Contrary to the state-of-the-art plasmonic logic devices, we use the phase of the wave instead of the intensity as the state or computational variable. We propose and demonstrate, via numerical simulations, a comprehensive scheme for building a nanoscale cascadable plasmonic majority logic gate along with a novel referencing scheme that can directly translate the information encoded in the amplitude and phase of the wave into electric field intensity at the output. Our MIM-based 3-input majority gate displays a highly improved overall area of only 0.636 mu m(2) for a single-stage compared with previous works on plasmonic logic. The proposed device demonstrates non-Boolean computational capability and can find direct utility in highly parallel real-time signal processing applications like pattern recognition.'));
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 4.259
Times cited: 2
DOI: 10.1038/S41598-017-17954-2
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“Skyrmion electrical detection with the use of three-dimensional Topological Insulators/Ferromagnetic bilayers”. Andrikopoulos D, Sorée B, Scientific reports 7, 17871 (2017). http://doi.org/10.1038/S41598-017-17727-X
Abstract: <script type='text/javascript'>document.write(unpmarked('The effect of the magnetic skyrmion texture on the electronic transport properties of the Tl surface state coupled to a thin-film FM is numerically investigated. It is shown that both Bloch (vortex) and Neel (hedgehog) skyrmion textures induce additional scattering on top of a homogeneous background FM texture which can modify the conductance of the system. The change in conductance depends on several factors including the skyrmion size, the dimensions of the FM and the exchange interaction strength. For the Neel skyrmion, the result of the interaction strongly depends on the skyrmion number N-sk and the skyrmion helicity h. For both skyrmion types, significant change of the resistance can be achieved, which is in the order of k Omega.'));
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 4.259
Times cited: 3
DOI: 10.1038/S41598-017-17727-X
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“Modeling electron competition among nitrogen oxides reduction and N2Oaccumulation in hydrogenotrophic denitrification”. Liu Y, Ngo HH, Guo W, Peng L, Chen X, Wang D, Pan Y, Ni B-J, Biotechnology and bioengineering 115, 978 (2018). http://doi.org/10.1002/BIT.26512
Abstract: Hydrogenotrophic denitrification is a novel and sustainable process for nitrogen removal, which utilizes hydrogen as electron donor, and carbon dioxide as carbon source. Recent studies have shown that nitrous oxide (N2O), a highly undesirable intermediate and potent greenhouse gas, can accumulate during this process. In this work, a new mathematical model is developed to describe nitrogen oxides dynamics, especially N2O, during hydrogenotrophic denitrification for the first time. The model describes electron competition among the four steps of hydrogenotrophic denitrification through decoupling hydrogen oxidation and nitrogen reduction processes using electron carriers, in contrast to the existing models that couple these two processes and also do not consider N2O accumulation. The developed model satisfactorily describes experimental data on nitrogen oxides dynamics obtained from two independent hydrogenotrophic denitrifying cultures under various hydrogen and nitrogen oxides supplying conditions, suggesting the validity and applicability of the model. The results indicated that N2O accumulation would not be intensified under hydrogen limiting conditions, due to the higher electron competition capacity of N2O reduction in comparison to nitrate and nitrite reduction during hydrogenotrophic denitrification. The model is expected to enhance our understanding of the process during hydrogenotrophic denitrification and the ability to predict N2O accumulation.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1002/BIT.26512
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“Estimating human health impacts and costs due to Iranian fossil fuel power plant emissions through the impact pathway approach”. Jorli M, Van Passel S, Sadeghi H, Nasseri A, Agheli L, Energies 10, 2136 (2017). http://doi.org/10.3390/EN10122136
Abstract: Air pollutants from fossil fuel fired power plants harm the environment and human health. More than 91% of Irans electricity production is from thermal power plants that use natural gas, diesel, and fuel oil. We apply the impact pathway approach to estimate the health impacts arising from Iranian fossil-based electricity generation emission, and in a next step, we calculate monetary costs of the estimated damages, for a one-year period starting from 20 March 2016 through 2017. We use the new version of SIMPACTS (International Atomic Energy Agency, Vienna, Austria) to investigate the health effects from 61 major Iran fossil-based power plants separately. The selected plants represent 95.6% of total Iran fossil-based power generation. Using the individual and different power plant estimates, we avoid extrapolation and our results can be considered more reliable, taking into account spatial differences. The total damage cost is 723.42 million USD (2000). The damage cost per generated electricity varies from 0.06 to 22.41 USD/MWh and average plant damage cost is 2.85 USD/MWh. Accounting for these external costs indicates the actual costs of fossil energy. The results are useful for policy makers to compare the health costs from these plants and to decide on cleaner energy sources and to take measures to increase benefits for society.
Keywords: A1 Journal article; Economics; Engineering sciences. Technology; Engineering Management (ENM)
Impact Factor: 2.262
Times cited: 4
DOI: 10.3390/EN10122136
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“Validation of inter-atomic potential for WS2 and WSe2 crystals through assessment of thermal transport properties”. Mobaraki A, Kandemir A, Yapicioglu H, Gulseren O, Sevik C, Computational materials science 144, 92 (2018). http://doi.org/10.1016/J.COMMATSCI.2017.12.005
Abstract: In recent years, transition metal dichalcogenides (TMDs) displaying astonishing properties are emerged as a new class of two-dimensional layered materials. The understanding and characterization of thermal transport in these materials are crucial for efficient engineering of 2D TMD materials for applications such as thermoelectric devices or overcoming general overheating issues. In this work, we obtain accurate Stillinger-Weber type empirical potential parameter sets for single-layer WS2 and WSe2 crystals by utilizing particle swarm optimization, a stochastic search algorithm. For both systems, our results are quite consistent with first-principles calculations in terms of bond distances, lattice parameters, elastic constants and vibrational properties. Using the generated potentials, we investigate the effect of temperature on phonon energies and phonon linewidth by employing spectral energy density analysis. We compare the calculated frequency shift with respect to temperature with corresponding experimental data, clearly demonstrating the accuracy of the generated inter-atomic potentials in this study. Also, we evaluate the lattice thermal conductivities of these materials by means of classical molecular dynamics simulations. The predicted thermal properties are in very good agreement with the ones calculated from first-principles. (C) 2017 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
DOI: 10.1016/J.COMMATSCI.2017.12.005
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“The influence of acids on tuning the pore size of mesoporous TiO2 templated by non-ionic block copolymers”. Loreto S, Vanrompay H, Mertens M, Bals S, Meynen V, European journal of inorganic chemistry 2018, 62 (2018). http://doi.org/10.1002/EJIC.201701266
Abstract: <script type='text/javascript'>document.write(unpmarked('We show the possibility to tune the pore size of mesoporous TiO2 templated by non-ionic block copolymers by adding different inorganic acids at well-chosen concentration. The effect of the inorganic anions on both the TiO2 cluster formation and the non-ionic block copolymers micelles is investigated to explain the experimental results.'));
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA)
Impact Factor: 2.444
Times cited: 6
DOI: 10.1002/EJIC.201701266
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“Comparative study of the magnetic properties of La3Ni2B'O9 for B' = Nb, Ta or Sb”. Chin C-M, Battle PD, Blundell SJ, Hunter E, Lang F, Hendrickx M, Sena RP, Hadermann J, Journal of solid state chemistry 258, 825 (2018). http://doi.org/10.1016/J.JSSC.2017.12.018
Abstract: Polycrystalline samples of La3Ni2NbO9 and La3Ni2TaO9 have been characterised by X-ray and neutron diffraction, electron microscopy, magnetometry and muon spin relaxation (mu SR); the latter technique was also applied to La3Ni2SbO9. On the length scale of a neutron diffraction experiment, the six-coordinate sites of the monoclinic perovskite structure are occupied in a 1:1 ordered manner by Ni and a random 1/3Ni/2/3B' mixture. Electron microscopy demonstrated that this 1:1 ordering is maintained over microscopic distances, although diffuse scattering indicative of short-range ordering on the mixed site was observed. No magnetic Bragg scattering was observed in neutron diffraction patterns collected from La3Ni2B'O-9 (B' = Nb or Ta) at 5 K although in each case mu SR identified the presence of static spins below 30 K. Magnetometry showed that La3Ni2NbO9 behaves as a spin glass below 29 K but significant short-range interactions are present in La3Ni2NbO9 below 85 K. The contrasting properties of these compounds are discussed in terms of their microstructure.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.299
Times cited: 6
DOI: 10.1016/J.JSSC.2017.12.018
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“Multicomponent electron-hole superfluidity and the BCS-BEC crossover in double bilayer graphene”. Conti S, Perali A, Peeters FM, Neilson D, Physical review letters 119, 257002 (2017). http://doi.org/10.1103/PHYSREVLETT.119.257002
Abstract: <script type='text/javascript'>document.write(unpmarked('Superfluidity in coupled electron-hole sheets of bilayer graphene is predicted here to be multicomponent because of the conduction and valence bands. We investigate the superfluid crossover properties as functions of the tunable carrier densities and the tunable energy band gap Eg. For small band gaps there is a significant boost in the two superfluid gaps, but the interaction-driven excitations from the valence to the conduction band can weaken the superfluidity, even blocking the system from entering the Bose-Einstein condensate (BEC) regime at low densities. At a given larger density, a band gap E-g similar to 80-120 meV can carry the system into the strong-pairing multiband BCS-BEC crossover regime, the optimal range for realization of high-Tc superfluidity.'));
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 8.462
Times cited: 18
DOI: 10.1103/PHYSREVLETT.119.257002
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“Spin-orbit semimetal SrIrO3 in the two-dimensional limit”. Groenendijk DJ, Autieri C, Girovsky J, Martinez-Velarte MC, Manca N, Mattoni G, Monteiro AMRVL, Gauquelin N, Verbeeck J, Otte AF, Gabay M, Picozzi S, Caviglia AD, Physical review letters 119, 256403 (2017). http://doi.org/10.1103/PHYSREVLETT.119.256403
Abstract: <script type='text/javascript'>document.write(unpmarked('We investigate the thickness-dependent electronic properties of ultrathin SrIrO3 and discover a transition from a semimetallic to a correlated insulating state below 4 unit cells. Low-temperature magnetoconductance measurements show that spin fluctuations in the semimetallic state are significantly enhanced while approaching the transition point. The electronic properties are further studied by scanning tunneling spectroscopy, showing that 4 unit cell SrIrO(3)d is on the verge of a gap opening. Our density functional theory calculations reproduce the critical thickness of the transition and show that the opening of a gap in ultrathin SrIrO3 requires antiferromagnetic order.'));
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 8.462
Times cited: 79
DOI: 10.1103/PHYSREVLETT.119.256403
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“Interplay of morphology, composition, and optical properties of InP-based quantum dots emitting at the 1.55 \mum telecom wavelength”. Carmesin C, Schowalter M, Lorke M, Mourad D, Grieb T, Müller-Caspary K, Yacob M, Reithmaier JP, Benyoucef M, Rosenauer A, Jahnke F, Physical review B 96, 235309 (2017). http://doi.org/10.1103/PHYSREVB.96.235309
Abstract: <script type='text/javascript'>document.write(unpmarked('Results for the development and detailed analysis of self-organized InAs/InAlGaAs/InP quantum dots suitable for single-photon emission at the 1.55 mu m telecom wavelength are reported. The structural and compositional properties of the system are obtained from high-resolution scanning transmission electron microscopy of individual quantum dots. The system is composed of almost pure InAs quantum dots embedded in quaternary InAlGaAs barrier material, which is lattice matched to the InP substrate. When using the measured results for a representative quantum-dot geometry as well as experimentally reconstructed alloy concentrations, a combination of strain-field and electronic-state calculations is able to reproduce the quantum-dot emission wavelength in agreement with the experimentally determined photoluminescence spectrum. The inhomogeneous broadening of the latter can be related to calculated variations of the emission wavelength for the experimentally deduced In-concentration fluctuations and size variations.'));
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 3
DOI: 10.1103/PHYSREVB.96.235309
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“Topological phase transitions in small mesoscopic chiral p-wave superconductors”. Zhang L-F, Covaci L, Milošević, MV, Physical review B 96, 224512 (2017). http://doi.org/10.1103/PHYSREVB.96.224512
Abstract: <script type='text/javascript'>document.write(unpmarked('Spin-triplet chiral p-wave superconductivity is typically described by a two-component order parameter, and as such is prone to unique emergent effects when compared to the standard single-component superconductors. Here we present the equilibrium phase diagram for small mesoscopic chiral p-wave superconducting disks in the presence of magnetic field, obtained by solving the microscopic Bogoliubov-de Gennes equations self-consistently. In the ultrasmall limit, the cylindrically symmetric giant-vortex states form the ground state of the system. However, with increasing sample size, the cylindrical symmetry is broken as the two components of the order parameter segregate into domains, and the number of fragmented domain walls between them characterizes the resulting states. Such domain walls are topological defects unique for the p-wave order, and constitute a dominant phase in the mesoscopic regime. Moreover, we find two possible types of domain walls, identified by their chirality-dependent interaction with the edge states.'));
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 18
DOI: 10.1103/PHYSREVB.96.224512
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“Titania-functionalized diatom frustules as photocatalyst for indoor air purification”. Ouwehand J, Van Eynde E, De Canck E, Lenaerts S, Verberckmoes A, Van der Voort P, Applied catalysis : B : environmental 226, 303 (2018). http://doi.org/10.1016/J.APCATB.2017.12.063
Abstract: Diatom frustules were extracted from the species Thalassiosira pseudonana and functionalized with titania to be used as photocatalysts in the abatement of acetaldehyde. The synthetic procedure is water-based and environmentally friendly. The synthesis parameters were optimized to give the highest possible photocatalytic activity. The optimized material, visualized with TEM and STEM-EDX, shows the TiO2 nanoparticles grafted inside the frustule pores, as well as on the silica surface. The titania particles, stabilized by the frustules, are 2.5 times more active than the P25 benchmark material. The photocatalyst is then tested in conditions of elevated relative humidity, to simulate indoor air. The catalytic activity only shows a minor decrease at 50% relative humidity, which is a better result than for the P25 benchmark. When tested over an extended period of time, the photocatalyst only shows a minor decrease in activity.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 9.446
Times cited: 4
DOI: 10.1016/J.APCATB.2017.12.063
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“Assessing the success of electricity demand response programs : a meta-analysis”. Srivastava A, Van Passel S, Laes E, Energy Research and Social Science 40, 110 (2018). http://doi.org/10.1016/J.ERSS.2017.12.005
Abstract: This paper conducts a meta-analysis of 32 electricity demand response programs in the residential sector to understand whether their success is dependent on specific characteristics. The paper analyses several regression models using various combinations of variables that capture the designs of the programs and the socio-economic conditions in which the programs are implemented. The analysis reveals that demand response programs are more likely to succeed in highly urbanized areas, in areas where economic growth rates are high, and in areas where the renewable energy policy is favorable. These findings provide useful guidance in determining where and how to implement future demand response programs.
Keywords: A1 Journal article; Economics; Engineering Management (ENM)
Times cited: 18
DOI: 10.1016/J.ERSS.2017.12.005
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“In situ tailoring of superconducting junctions via electro-annealing”. Lombardo J, Jelić, ŽL, Baumans XDA, Scheerder JE, Nacenta JP, Moshchalkov VV, Van de Vondel J, Kramer RBG, Milošević, MV, Silhanek AV, Nanoscale 10, 1987 (2018). http://doi.org/10.1039/C7NR08571K
Abstract: We demonstrate the in situ engineering of superconducting nanocircuitry by targeted modulation of material properties through high applied current densities. We show that the sequential repetition of such customized electro-annealing in a niobium (Nb) nanoconstriction can broadly tune the superconducting critical temperature T-c and the normal-state resistance R-n in the targeted area. Once a sizable R-n is reached, clear magneto-resistance oscillations are detected along with a Fraunhofer-like field dependence of the critical current, indicating the formation of a weak link but with further adjustable characteristics. Advanced Ginzburg-Landau simulations fully corroborate this picture, employing the detailed parametrization from the electrical characterization and high resolution electron microscope images of the region within the constriction where the material has undergone amorphization by electro-annealing.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 7.367
Times cited: 23
DOI: 10.1039/C7NR08571K
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“Structural, mechanical and electronic properties of two-dimensional structure of III-arsenide (111) binary compounds: An ab-initio study”. Gonzalez-Garcia A, Lopez-Perez W, Rivera-Julio J, Peeters FM, Mendoza-Estrada V, Gonzalez-Hernandez R, Computational materials science 144, 285 (2018). http://doi.org/10.1016/J.COMMATSCI.2017.12.050
Abstract: Structural, mechanical and electronic properties of two-dimensional single-layer hexagonal structures in the (111) crystal plane of IIIAs-ZnS systems (III = B, Ga and In) are studied by first-principles calculations based on density functional theory (DFT). Elastic and phonon dispersion relation display that 2D h-IIIAs systems (III = B, Ga and In) are both mechanical and dynamically stable. Electronic structures analysis show that the semiconducting nature of the 3D-IIIAs compounds is retained by their 2D single layer counterpart. Furthermore, density of states reveals the influence of sigma and pi bonding in the most stable geometry (planar or buckled) for 2D h-IIIAs systems. Calculations of elastic constants show that the Young's modulus, bulk modulus and shear modulus decrease for 2D h-IIIAs binary compounds as we move down on the group of elements of the periodic table. In addition, as the bond length between the neighboring cation-anion atoms increases, the 2D h-IIIAs binary compounds display less stiffness and more plasticity. Our findings can be used to understand the contribution of the r and p bonding in the most stable geometry (planar or buckled) for 2D h-IIIAs systems. Structural and electronic properties of h-IIIAs systems as a function of the number of layers have been also studied. It is shown that h-BAs keeps its planar geometry while both h-GAs and h-InAs retained their buckled ones obtained by their single layers. Bilayer h-IIIAs present the same bandgap nature of their counterpart in 3D. As the number of layers increase from 2 to 4, the bandgap width for layered h-IIIAs decreases until they become semimetal or metal. Interestingly, these results are different to those found for layered h-GaN. The results presented in this study for single and few-layer h-IIIAs structures could give some physical insights for further theoretical and experimental studies of 2D h-IIIV-like systems. (C) 2017 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.292
Times cited: 3
DOI: 10.1016/J.COMMATSCI.2017.12.050
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“Ein Whirlpool aus Elektronen: Transmissions-Elektronenmikroskopie mit Elektronenwirbeln”. Schattschneider P, Schachinger T, Verbeeck J, Physik in unserer Zeit 49, 22 (2018). http://doi.org/10.1002/piuz.201801495
Abstract: Elektronen bewegen sich im feldfreien Raum immer gleichförmig geradlinig, so steht es in den Lehrbüchern. Falsch, sagen wir. Elektronen lassen sich zu Tornados formen, die theoretisch Nanopartikel zerreißen können. In der Elektronenmikroskopie eingesetzt, versprechen sie neue Erkenntnisse in der Festkörperphysik.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.1002/piuz.201801495
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“MXenes/graphene heterostructures for Li battery applications : a first principles study”. Aierken Y, Sevik C, Gulseren O, Peeters FM, Çakir D, Journal of materials chemistry A : materials for energy and sustainability 6, 2337 (2018). http://doi.org/10.1039/C7TA09001C
Abstract: MXenes are the newest class of two-dimensional (2D) materials, and they offer great potential in a wide range of applications including electronic devices, sensors, and thermoelectric and energy storage materials. In this work, we combined the outstanding electrical conductivity, that is essential for battery applications, of graphene with MXene monolayers (M2CX2 where M = Sc, Ti, V and X = OH, O) to explore its potential in Li battery applications. Through first principles calculations, we determined the stable stacking configurations of M2CX2/graphene bilayer heterostructures and their Li atom intercalation by calculating the Li binding energy, diffusion barrier and voltage. We found that: (1) for the ground state stacking, the interlayer binding is strong, yet the interlayer friction is small; (2) Li binds more strongly to the O-terminated monolayer, bilayer and heterostructure MXene systems when compared with the OHterminated MXenes due to the H+ induced repulsion to the Li atoms. The binding energy of Li decreases as the Li concentration increases due to enhanced repulsive interaction between the positively charged Li ions; (3) Ti2CO2/graphene and V2CO2/graphene heterostructures exhibit large Li atom binding energies making them the most promising candidates for battery applications. When fully loaded with Li atoms, the binding energy is -1.43 eV per Li atom and -1.78 eV per Li atom for Ti2CO2/graphene and V2CO2/graphene, respectively. These two heterostructures exhibit a nice compromise between storage capacity and kinetics. For example, the diffusion barrier of Li in Ti2CO2/graphene is around 0.3 eV which is comparable to that of graphite. Additionally, the calculated average voltages are 1.49 V and 1.93 V for Ti2CO2/graphene and V2CO2/graphene structures, respectively; (4) a small change in the in-plane lattice parameters (<1%), interatomic bond lengths and interlayer distances (<0.5 angstrom) proves the stability of the heterostructures against Li intercalation, and the impending phase separation into constituent layers and capacity fading during charge-discharge cycles in real battery applications; (5) as compared to bare M2CX2 bilayers, M2CX2/graphene heterostructures have lower molecular mass, offering high storage capacity; (6) the presence of graphene ensures good electrical conductivity that is essential for battery applications. Given these advantages, Ti2CO2/graphene and V2CO2/graphene heterostructures are predicted to be promising for lithium-ion battery applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 8.867
Times cited: 131
DOI: 10.1039/C7TA09001C
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“IR reflectography and active thermography on artworks : the added value of the 1.53 µm band”. Peeters J, Steenackers G, Sfarra S, Legrand S, Ibarra-Castanedo C, Janssens K, van der Snickt G, Applied Sciences 8, 50 (2018). http://doi.org/10.3390/APP8010050
Abstract: Infrared Radiation (IR) artwork inspection is typically performed through active thermography and reflectography with different setups and cameras. While Infrared Radiation Reflectography (IRR) is an established technique in the museum field, exploiting mainly the IR-A (0.71.4 µm) band to probe for hidden layers and modifications within the paint stratigraphy system, active thermography operating in the IR-C range (35 μ m) is less frequently employed with the aim to visualize structural defects and features deeper inside the build-up. In this work, we assess to which extent the less investigated IR-B band (1.53 μ m) can combine the information obtained from both setups. The application of IR-B systems is relatively rare as there are only a limited amount of commercial systems available due to the technical complexity of the lens coating. This is mainly added as a so-called broadband option on regular Mid-wave infrared radiation (MWIR) (IR-C/35 μ m) cameras to increase sensitivity for high temperature applications in industry. In particular, four objects were studied in both reflectographic and thermographic mode in the IR-B spectral range and their results benchmarked with IR-A and IR-C images. For multispectral application, a single benchmark is made with macroscopic reflection mode Fourier transform infrared (MA-rFTIR) results. IR-B proved valuable for visualisation of underdrawings, pencil marks, canvas fibres and wooden grain structures and potential pathways for additional applications such as pigment identification in multispectral mode or characterization of the support (panels, canvas) are indicated.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 1.679
Times cited: 4
DOI: 10.3390/APP8010050
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“Advanced first-principles theory of superconductivity including both lattice vibrations and spin fluctuations : the case of FeB4”. Bekaert J, Aperis A, Partoens B, Oppeneer PM, Milošević, MV, Physical review B 97, 014503 (2018). http://doi.org/10.1103/PHYSREVB.97.014503
Abstract: <script type='text/javascript'>document.write(unpmarked('We present an advanced method to study spin fluctuations in superconductors quantitatively and entirely from first principles. This method can be generally applied to materials where electron-phonon coupling and spin fluctuations coexist. We employ it here to examine the recently synthesized superconductor iron tetraboride (FeB4) with experimental T-c similar to 2.4 K [H. Gou et al., Phys. Rev. Lett, 111, 157002 (2013)]. We prove that FeB4 is particularly prone to ferromagnetic spin fluctuations due to the presence of iron, resulting in a large Stoner interaction strength, I = 1.5 eV, as calculated from first principles. The other important factor is its Fermi surface that consists of three separate sheets, among which two are nested ellipsoids. The resulting susceptibility has a ferromagnetic peak around q = 0, from which we calculated the repulsive interaction between Cooper pair electrons using the random phase approximation. Subsequently, we combined the electron-phonon interaction calculated from first principles with the spin fluctuation interaction in fully anisotropic Eliashberg theory calculations. We show that the resulting superconducting gap spectrum is conventional, yet very strongly depleted due to coupling to the spin fluctuations. The critical temperature decreases from T-c = 41 K, if they are not taken into account, to T-c = 1.7 K, in good agreement with the experimental value.'));
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 23
DOI: 10.1103/PHYSREVB.97.014503
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“Influence of stress aging process on variants of nano-N4Ti3precipitates and martensitic transformation temperatures in NiTi shape memory alloy”. Radi A, Khalil-Allafi J, Etminanfar MR, Pourbabak S, Schryvers D, Amin-Ahmadi B, Materials &, design 262, 74 (2018). http://doi.org/10.1016/J.ELECTACTA.2018.01.024
Abstract: In this study, the effect of a stress aging process on the microstructure and martensitic phase transformation of NiTi shape memory alloy has been investigated. NiTi samples were aged at 450 degrees C for 1 h and 5 h under different levels of external tensile stress of 15, 60 and 150 MPa. Transmission electron microscopy (TEM) was used to characterize different variants and morphology of precipitates. The results show that application of all stress levels restricts the formation of precipitates variants in the microstructure after I h stress aging process. However, all variants can be detected by prolonging aging time to 5 h at 15 MPa stress level and the variants formation is again restricted by increasing the stress level. Moreover, the stress aging process resulted in changing the shape of precipitates in comparison with that of the stress-free aged samples. Coffee-bean shaped morphologies were detected for precipitates in all stress levels. According to the Differential Scanning Calorimetry (DSC) results, the martensite start temperature (M-s) on cooling shifts to higher temperatures with increasing the tensile stress during the aging process. This can be related to the change ofaustenite to martensite interface energy due to the different volume fractions and variants of precipitates. (c) 2018 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.364
DOI: 10.1016/J.ELECTACTA.2018.01.024
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“Development of a new portable X-ray powder diffractometer and its demonstration to on-site analysis of two selected old master paintings from the Rijksmuseum”. Hirayama A, Abe Y, van Loon A, De Keyser N, Noble P, Vanmeert F, Janssens K, Tantrakarn K, Taniguchi K, Nakai I, Microchemical journal 138, 266 (2018). http://doi.org/10.1016/J.MICROC.2018.01.003
Abstract: A portable X-ray powder diffractometer (p-XRD) PT-APXRD III has been developed for onsite analysis of paintings and archaeological samples. By using a Cu anode X-ray tube and a silicon drift diode (SDD) detector, diffraction patterns with a high signalnoise (S/N) ratio can be recorded. The X-ray tube can be operated at a maximum voltage of 60 kV, which makes it possible to simultaneously record X-ray fluorescence spectra up to the high-energy region. The total weight of this instrument is 16 kg, which can be carried anywhere and the goniometer unit (5.6 kg) can be placed on a tripod for analysis of mural paintings. We brought the instrument to the Rijksmuseum in the Netherlands to examine its applicability for the analysis of oil paintings. We successfully analyzed two seventeenthcentury oil paintings by Johannes Vermeer and Jan Davidsz de Heem (copy after). Ultramarine blue, leadtin yellow type I, and Naples yellow were identified from the diffraction patterns, demonstrating the high practicality of this instrument. Furthermore, it was found from the SEM-EDX analysis of a paint cross section that the yellow pigment was applied in separate layers rather than being mixed. This diffractometer will be commercially available in the near future and will have many applications in the field of material analysis. (C) 2018 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.034
Times cited: 2
DOI: 10.1016/J.MICROC.2018.01.003
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“Combining experimental and modelling approaches to study the sources of reactive species induced in water by the COST RF plasma jet”. Gorbanev Y, Verlackt CCW, Tinck S, Tuenter E, Foubert K, Cos P, Bogaerts A, Physical chemistry, chemical physics 20, 2797 (2018). http://doi.org/10.1039/C7CP07616A
Abstract: The vast biomedical potential of cold atmospheric pressure plasmas (CAPs) is governed by the formation of reactive species. These biologically active species are formed upon the interaction of CAPs with the surroundings. In biological milieu, water plays an essential role. The development of biomedical CAPs thus requires understanding of the sources of the reactive species in aqueous media exposed to the plasma. This is especially important in case of the COST RF plasma jet, which is developed as a reference microplasma system. In this work, we investigated the formation of the OH radicals, H atoms and H2O2 in aqueous solutions exposed to the COST plasma jet. This was done by combining experimental and modelling approaches. The liquid phase species were analysed using UV-Vis spectroscopy and spin trapping with hydrogen isotopes and electron paramagnetic resonance (EPR) spectroscopy. The discrimination between the species formed from the liquid phase and the gas phase molecules was performed by EPR and 1H-NMR analyses of the liquid samples. The concentrations of the reactive species in the gas phase plasma were obtained using a zero-dimensional (0D) chemical kinetics computational model. A three-dimensional (3D) fluid dynamics model was developed to provide information on the induced humidity in the plasma effluent. The comparison of the experimentally obtained trends for the formation of the species as a function of the feed gas and effluent humidity with the modelling results suggest that all reactive species detected in our system are mostly formed in the gas phase plasma inside the COST jet, with minor amounts arising from the plasma effluent humidity.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.123
Times cited: 23
DOI: 10.1039/C7CP07616A
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“Non-invasive analysis of a 15th century illuminated manuscript fragment: point-based vs imaging spectroscopy”. Legrand S, Ricciardi P, Nodari L, Janssens K, Microchemical journal 138, 162 (2018). http://doi.org/10.1016/J.MICROC.2018.01.001
Abstract: Illuminated manuscript fragments are some of the best preserved objects of Western cultural heritage. Therefore, scholars are limited to non-invasive – often point-based – methods, to answer questions on material usage, technique, origin and previous treatments. These powerful methods yield specific information; however, the information is limited to the number of points analyzed. Imaging spectroscopies such as MA-XRF and MA-rFTIR combine specificity with the power of imaging, resulting in distribution images that are interpretable by non-spectroscopists and the public at large. In this paper the possible added value of using imaging spectroscopy is discussed. Do these methods yield the same results as an extensive point-based spectroscopic campaign and can they bring novel information? As a case study, a 15th century illuminated manuscript fragment is employed in order to explore the differences between these approaches and present an inventory of their advantages and limitations. (C) 2018 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.034
Times cited: 12
DOI: 10.1016/J.MICROC.2018.01.001
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“Assessing the stability of arsenic sulfide pigments and influence of the binding media on their degradation by means of spectroscopic and electrochemical techniques”. Vermeulen M, Janssens K, Sanyova J, Rahemi V, McGlinchey C, De Wael K, Microchemical journal 138, 82 (2018). http://doi.org/10.1016/J.MICROC.2018.01.004
Abstract: In this paper, we used the semiconducting and lightfastness properties of synthetic and mineral arsenic sulfide pigments to study their stability by means of electrochemical and microfadometric techniques. A combination of these techniques shows that in the early stage of the degradation process, amorphous arsenic sulfides are more stable than both crystalline forms, while upon longer exposure time, amorphous pigments will fade more than both mineral pigments, making it less suitable. While the stability study was carried out on unbound pigments, the influence of the organic binder on the relative degradation of the arsenic sulfide pigments was investigated through a multi-analytical approach on pigment/binder mock-up paint samples. For this purpose, the formation of arsenic trioxide was assessed by micro Fourier transform infrared (μ-FTIR) spectroscopy while the influence of the binder on the formation of sulfates was studied by means of synchrotron radiation X-ray near edge structure (μ-XANES). Both techniques elucidate a higher stability of all pigments in gum arabic while the use of egg yolk as binder leads to the most degradation, most likely due to its sulfur-rich composition. In the context of the degradation of arsenic sulfide pigments, other binders such as animal glue, egg white or linseed oil show an intermediate impact.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.034
Times cited: 4
DOI: 10.1016/J.MICROC.2018.01.004
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“TiO2 Films Modified with Au Nanoclusters as Self-Cleaning Surfaces under Visible Light”. Liao T-W, Verbruggen S, Claes N, Yadav A, Grandjean D, Bals S, Lievens P, Nanomaterials 8, 30 (2018). http://doi.org/10.3390/nano8010030
Abstract: In this study, we applied cluster beam deposition (CBD) as a new approach for fabricating efficient plasmon-based photocatalytic materials. Au nanoclusters (AuNCs) produced in the gas phase were deposited on TiO2 P25-coated silicon wafers with coverage ranging from 2 to 8 atomic monolayer (ML) equivalents. Scanning Electron Microscopy (SEM) images of the AuNCs modified TiO2 P25 films show that the surface is uniformly covered by the AuNCs that remain isolated at low coverage (2 ML, 4 ML) and aggregate at higher coverage (8 ML). A clear relationship between AuNCs coverage and photocatalytic activity towards stearic acid photo-oxidation was measured, both under ultraviolet and green light illumination. TiO2 P25 covered with 4 ML AuNCs showed the best stearic acid photo-oxidation performance under green light illumination (Formal Quantum Efficiency 1.6 x 10-6 over a period of 93 h). These results demonstrate the large potential of gas-phase AuNCs beam deposition technology for the fabrication of visible light active plasmonic photocatalysts.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 3.553
Times cited: 29
DOI: 10.3390/nano8010030
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“Gold nanoclusters with bright near-infrared photoluminescence”. Pramanik G, Humpolickova J, Valenta J, Kundu P, Bals S, Bour P, Dracinsky M, Cigler P, Nanoscale 10, 3792 (2018). http://doi.org/10.1039/C7NR06050E
Abstract: The increase in nonradiative pathways with decreasing emission energy reduces the luminescence quantum yield (QY) of near-infrared photoluminescent (NIR PL) metal nanoclusters. Efficient surface ligand chemistry can significantly improve the luminescence QY of NIR PL metal nanoclusters. In contrast to the widely reported but modestly effective thiolate ligand-to-metal core charge transfer, we show that metal-to-ligand charge transfer (MLCT) can be used to greatly enhance the luminescence QY of NIR PL gold nanoclusters (AuNCs). We synthesized water-soluble and colloidally stable NIR PL AuNCs with unprecedentedly high QY (similar to 25%) upon introduction of triphenylphosphonium moieties into the surface capping layer. By using a combination of spectroscopic and theoretical methods, we provide evidence for gold core-to-ligand charge transfer occurring in AuNCs. We envision that this work can stimulate the development of these unusually bright AuNCs for promising optoelectronic, bioimaging, and other applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 7.367
Times cited: 97
DOI: 10.1039/C7NR06050E
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“A comparative DFT study on CO oxidation reaction over Si-doped BC2N nanosheet and nanotube”. Nematollahi P, Neyts EC, Applied surface science 439, 934 (2018). http://doi.org/10.1016/J.APSUSC.2017.12.254
Abstract: In this study, we performed density functional theory (DFT) calculations to investigate different reaction mechanisms of CO oxidation catalyzed by the Si atom embedded defective BC2N nanostructures as well as the analysis of the structural and electronic properties. The structures of all the complexes are optimized and characterized by frequency calculations at the M062X/6-31G* computational level. Also, The electronic structures and thermodynamic parameters of adsorbed CO and O-2 molecules over Si-doped BC2N nanostructures are examined in detail. Moreover, to investigate the curvature effect on the CO oxidation reaction, all the adsorption and CO oxidation reactions on a finite-sized armchair (6,6) Si-BC2NNT are also studied. Our results indicate that there can be two possible pathways for the CO oxidation with O-2 molecule: O-2(g) + CO(g) -> O-2(ads) + CO(ads) -> CO2(g) + O-(ads) and O-(ads) + CO(g) -> CO2(g). The first reaction proceeds via the Langmuir-Hinshelwood (LH) mechanism while the second goes through the Eley-Rideal (ER) mechanism. On the other hand, by increasing the tube diameter, the energy barrier increases due to the strong adsorption energy of the O-2 molecule which is related to its dissociation over the tube surface. Our calculations indicate that the two step energy barrier of the oxidation reaction over Si-BC2NNS is less than that over the Si-BC2NNT. Hence, Si-BC2NNS may serve as an efficient and highly activated substrate to CO oxidation rather than (4,4) Si-BC2NNT. (C) 2018 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.387
Times cited: 8
DOI: 10.1016/J.APSUSC.2017.12.254
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