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“Extending and validating bubble nucleation rate predictions in a Lennard-Jones fluid with enhanced sampling methods and transition state theory”. Bal KM, Neyts EC, Journal Of Chemical Physics 157, 184113 (2022). http://doi.org/10.1063/5.0120136
Abstract: We calculate bubble nucleation rates in a Lennard-Jones fluid through explicit molecular dynamics simulations. Our approach-based on a recent free energy method (dubbed reweighted Jarzynski sampling), transition state theory, and a simple recrossing correction-allows us to probe a fairly wide range of rates in several superheated and cavitation regimes in a consistent manner. Rate predictions from this approach bridge disparate independent literature studies on the same model system. As such, we find that rate predictions based on classical nucleation theory, direct brute force molecular dynamics simulations, and seeding are consistent with our approach and one another. Published rates derived from forward flux sampling simulations are, however, found to be outliers. This study serves two purposes: First, we validate the reliability of common modeling techniques and extrapolation approaches on a paradigmatic problem in materials science and chemical physics. Second, we further test our highly generic recipe for rate calculations, and establish its applicability to nucleation processes.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.4
DOI: 10.1063/5.0120136
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“Quantum transport in a cylindrical sub-0.1 μm silicon-based MOSFET”. Balaban SN, Pokatilov EP, Fomin VM, Gladilin VN, Devreese JT, Magnus W, Schoenmaker W, van Rossum M, Sorée B, Solid-State Electronics 46, 435 (2002). http://doi.org/10.1016/S0038-1101(01)00117-4
Keywords: A1 Journal article; Electron Microscopy for Materials Science (EMAT);
Impact Factor: 1.58
Times cited: 16
DOI: 10.1016/S0038-1101(01)00117-4
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“A covalently linked dyad based on zinc phthalocyanine and methylpheophorbide &alpha, : synthetic and physicochemical study”. Balashova IO, Tolbin AY, Tarakanov PA, Krot AR, Fedorova K V, Sergeeva IA, Trashin SA, De Wael K, Pushkarev VE, Koifman MO, Ponomarev G V, Macroheterocycles 14, 40 (2021). http://doi.org/10.6060/MHC210338P
Abstract: The first covalently linked conjugate of metal phthalocyaninate and chlorin e(6) derivative has been obtained by transesterification of alpha-ketomethyl ester in methylpheophorbide a with zinc(II) 2-(2-hydroxymethylbenzyloxy)-9(10),16(17),23(24)-tri-tert-butylphthalocyaninate under mild conditions. The dyad exhibits a panchromatic nature revealing both the phthalocyanine and pheophorbide derived bands in the UV-Vis absorption spectrum. The H-1 NMR spectroscopy data combined with theoretical calculations indicate the presence of spatial intramolecular interactions between the phthalocyanine, pheophorbide and spacer fragments of the dyad allowing to forecast its enhanced nonlinear optical properties, as well as the characteristic energy transfer from the excited pheophorbide subunit to the phthalocyanine core. Indeed, when excited in the UV-Vis range, the conjugate shows red fluorescence with the spectral maximum at 686 nm, which is close to the one of the initial zinc phthalocyaninate. Furthermore, the dyad effectively generates singlet oxygen and, in the presence of polyvinylpyrrolidone (PVP) as biocompatible solubilizer, forms stable micellar saline solutions with the particles ranged in size between 40 and 100 nm. These nanoparticles represent promising third-generation photosensitizing systems for application in theranostics.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.6060/MHC210338P
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“The analysis of macrotwins in NiAl martensite”. Ball JM, Schryvers D, Journal de physique: 4
T2 –, 10th International Conference on Martensitic Transformations, JUN 10-14, 2002, ESPOO, FINLAND 112, 159 (2003). http://doi.org/10.1051/jp4:2003855
Abstract: We present a theoretical study of macrotwins arising in cubic to tetragonal martensitic transformations. The results help to explain some features of such macrotwins observed in Ni65Al35.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 11
DOI: 10.1051/jp4:2003855
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“Three-dimensional atomic imaging of colloidal core-shell nanocrystals”. Bals S, Casavola M, van Huis MA, Van Aert S, Batenburg KJ, Van Tendeloo G, Vanmaekelbergh D, Nano letters 11, 3420 (2011). http://doi.org/10.1021/nl201826e
Abstract: Colloidal coreshell semiconductor nanocrystals form an important class of optoelectronic materials, in which the exciton wave functions can be tailored by the atomic configuration of the core, the interfacial layers, and the shell. Here, we provide a trustful 3D characterization at the atomic scale of a free-standing PbSe(core)CdSe(shell) nanocrystal by combining electron microscopy and discrete tomography. Our results yield unique insights for understanding the process of cation exchange, which is widely employed in the synthesis of coreshell nanocrystals. The study that we present is generally applicable to the broad range of colloidal heteronanocrystals that currently emerge as a new class of materials with technological importance.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 12.712
Times cited: 121
DOI: 10.1021/nl201826e
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“Three-dimensional characterization of noble-metal nanoparticles and their assemblies by electron tomography”. Bals S, Goris B, Liz-Marzan LM, Van Tendeloo G, Angewandte Chemie: international edition in English 53, 10600 (2014). http://doi.org/10.1002/anie.201401059
Abstract: New developments in the field of nanomaterials drive the need for quantitative characterization techniques that yield information down to the atomic scale. In this Review, we focus on the three-dimensional investigations of metal nanoparticles and their assemblies by electron tomography. This technique has become a versatile tool to understand the connection between the properties and structure or composition of nanomaterials. The different steps of an electron tomography experiment are discussed and we show how quantitative three-dimensional information can be obtained even at the atomic scale.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 11.994
Times cited: 58
DOI: 10.1002/anie.201401059
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“Annular dark field imaging in a TEM”. Bals S, Kabius B, Haider M, Radmilovic V, Kisielowski C, Solid state communications 130, 675 (2004). http://doi.org/10.1016/j.ssc.2004.03.035
Abstract: Annular objective apertures are fabricated for a CM300 transmission electron microscope using a focused ion beam system. A central beam stop in the back focal plane of the objective lens of the microscope blocks all electrons scattered up to a semi-angle of approximately 20 mrad. In this manner, contributions to the image from Bragg scattering are largely reduced and the image contrast is sensitive to the atomic number Z. Experimentally, we find that single atom scattering cross sections measured with this technique are close to Rutherford scattering values. A comparison between this new method and STEM-HAADF shows that both techniques result in qualitatively similar images although the resolution of ADF-TEM is limited by contrast delocalization caused by the spherical aberration of the objective lens. This problem can be overcome by using an aberration corrected microscope.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.554
Times cited: 43
DOI: 10.1016/j.ssc.2004.03.035
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“Tomography using annular dark field imaging in TEM”. Bals S, Kisielowski C, Croitoru M, Van Tendeloo G, Microscopy and microanalysis 11, 2118 (2005)
Keywords: A3 Journal article; Condensed Matter Theory (CMT); Electron microscopy for materials research (EMAT)
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“Atomic scale dynamics of ultrasmall germanium clusters”. Bals S, Van Aert S, Romero CP, Lauwaet K, Van Bael MJ, Schoeters B, Partoens B, Yuecelen E, Lievens P, Van Tendeloo G, Nature communications 3, 897 (2012). http://doi.org/10.1038/ncomms1887
Abstract: Starting from the gas phase, small clusters can be produced and deposited with huge flexibility with regard to composition, materials choice and cluster size. Despite many advances in experimental characterization, a detailed morphology of such clusters is still lacking. Here we present an atomic scale observation as well as the dynamical behaviour of ultrasmall germanium clusters. Using quantitative scanning transmission electron microscopy in combination with ab initio calculations, we are able to characterize the transition between different equilibrium geometries of a germanium cluster consisting of less than 25 atoms. Seven-membered rings, trigonal prisms and some smaller subunits are identified as possible building blocks that stabilize the structure.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Impact Factor: 12.124
Times cited: 90
DOI: 10.1038/ncomms1887
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“Optimisation of superconducting thin films by TEM”. Bals S, Van Tendeloo G, Rijnders G, Blank DHA, Leca V, Salluzzo M, Physica: C : superconductivity 372/376, 711 (2002). http://doi.org/10.1016/S0921-4534(02)00838-9
Abstract: High-resolution electron microscopy is used to study the initial growth of different REBa2CU3O7-5 thin films. In DyBa2CU3O7-5 ultra-thin films, deposited on TiO2 terminated SrTiO3, two different types of interface arrangements occur: bulk-SrO-TiO2-BaO-CuO-BaO-CuO2-Dy-CuO2-BaO-bulk and bulk-SrO-TiO2-BaO-CuO2-Dy-CuO2-BaO-CuO-BaO-bulk. This variable growth sequence is the origin of the presence of antiphase boundaries. In Nd1+xBa2-xCu3O7-5 thin films, antiphase boundaries tend to annihilate by the insertion of extra Nd-layers. This annihilation is correlated with the flat morphology of the film and the absence of growth spirals at the surface of the Nd-rich films. (C) 2002 Elsevier Science B.V. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.404
Times cited: 6
DOI: 10.1016/S0921-4534(02)00838-9
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“Transmission electron microscopy on interface engineered superconducting thin films”. Bals S, Van Tendeloo G, Rijnders G, Huijben M, Leca V, Blank DHA, IEEE transactions on applied superconductivity 13, 2834 (2003). http://doi.org/10.1109/TASC.2003.812023
Abstract: Transmission electron microscopy is used to evaluate different deposition techniques, which optimize the microstructure and physical properties of superconducting thin films. High-resolution electron microscopy proves that the use of an YBa2Cu2Ox buffer layer can avoid a variable interface configuration in YBa2Cu3O7-delta thin films grown on SrTiO3. The growth can also be controlled at an atomic level by, using sub-unit cell layer epitaxy, which results in films with high quality and few structural defects. Epitaxial strain in Sr0.85La0.15CuO2 infinite layer thin films influences the critical temperature of these films, as well as the microstructure. Compressive stress is released by a modulated or a twinned microstructure, which eliminates superconductivity. On the other hand, also tensile strain seems to lower the critical temperature of the infinite layer.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 13
DOI: 10.1109/TASC.2003.812023
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“Why are sputter deposited Nd1+xBa2-xCu3O7-\delta thin films flatter than NdBa2Cu3O7-\delta films?”.Bals S, Van Tendeloo G, Salluzzo M, Maggio-Aprile I, Applied physics letters 79, 3660 (2001). http://doi.org/10.1063/1.1421622
Abstract: High-resolution electron microscopy and scanning tunneling microscopy have been used to compare the microstructure of NdBa2Cu3O7-delta and Nd1+xBa2-xCu3O7-delta thin films. Both films contain comparable amounts of Nd2CuO4 inclusions. Antiphase boundaries are induced by unit cell high steps at the substrate or by a different interface stacking. In Nd1+xBa2-xCu3O7-delta the antiphase boundaries tend to annihilate by the insertion of extra Nd layers. Stacking faults, which can be characterized as local Nd2Ba2Cu4O9 inclusions, also absorb the excess Nd. A correlation is made between the excess Nd and the absence of growth spirals at the surface of the Nd-rich films. (C) 2001 American Institute of Physics.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.411
Times cited: 13
DOI: 10.1063/1.1421622
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“Modeling the charge deposition in quartz grains during natural irradiation and its influence on the optically stimulated luminescence signal”. Baly L, Quesada I, Murray AS, Martin G, van Espen P, Arteche R, Jain M, Radiation Measurements 142, 106564 (2021). http://doi.org/10.1016/J.RADMEAS.2021.106564
Abstract: The rate of charge deposition in quartz grains irradiated in natural conditions is computed by radiation transport modeling. Quartz luminescence models are modified with the addition of the resulting charge deposition term, and the influence of this process on the optically stimulated luminescence (OSL) signal is analyzed. The results indicate that the charge deposition occurring in the quartz grain during the time of residence within rock could lead to the depletion of trapped holes in the recombination centres. For the two different quartz models investigated here, complete depletion is expected to occur for rock ages between 500 Ma and 1100 Ma. It is predicted that for sedimentary quartz derived from such rocks, the OSL signal is dominated by the slow component. It was also found that the shape and saturation level of the natural sensitivity-corrected dose response curve (DRC) of quartz is affected by the charge deposition; specifically, a linear reduction of the saturation level with the age of the rock is observed.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 1.442
DOI: 10.1016/J.RADMEAS.2021.106564
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“Importance of design and operating parameters in a sonication system for viscous solutions : effects of input power, horn tip diameter and reactor capacity”. Bampouli A, Goris Q, Hussain MN, Louisnard O, Stefanidis GD, Van Gerven T, Chemical engineering and processing 198, 109715 (2024). http://doi.org/10.1016/J.CEP.2024.109715
Abstract: This study investigates the distribution of ultrasound (US) energy in a batch system for solutions with viscosity ranging from 1 to approximately 3000 mPas. Sonication was performed using horn type configurations operating at 20-30 kHz and rated power capacity of 50 or 200 W. Two different tip diameters (3 or 7 mm) and two insertion depths (35 or 25 mm) within vessels of different sizes ( approximate to 60 or 130 ml) were utilized. Additionally, a special conical tip design was employed. For each experimental setup, the calorimetric efficiency was estimated, the cavitationally active regions were visualized using the sonochemiluminescence (SCL) method and bubble cluster formation inside the vessel was macroscopically observed using a high speed camera (HSC). In the viscosity range tested, the calorimetry results showed that the efficiency and continuous operation of the device depend on both the rated power and the horn tip diameter. The ratio between electrical and calorimetric power input remained consistently around 40 to 50% across the different configurations for water, but for the 123.2 mPas solution exhibited significant variation ranging from 40 to 85%. Moreover, the power density in the smaller reactor was found to be nearly double compared to the larger one. The SCL analysis showed multiple cavitationally active zones in all setups, and the zones intensity decreased considerably with increase of the solutions viscosity. The results for the cone tip were not conclusive, but can be used as the basis for further investigation. The current research highlights the importance of thoroughly understanding the impact of each design parameter, and of establishing characterization methodologies to assist in the future development of scaled-up, commercial applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.3
DOI: 10.1016/J.CEP.2024.109715
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“Rheology of amorphous olivine thin films characterized by nanoindentation”. Baral P, Orekhov A, Dohmen R, Coulombier M, Raskin JP, Cordier P, Idrissi H, Pardoen T, Acta Materialia 219, 117257 (2021). http://doi.org/10.1016/J.ACTAMAT.2021.117257
Abstract: The rheological properties of amorphous olivine thin films deposited by pulsed laser deposition have been studied based on ambient temperature nanoindentation under constant strain-rate as well as re-laxation conditions. The amorphous olivine films exhibit a viscoelastic-viscoplastic behavior with a significant rate dependency. The strain-rate sensitivity m is equal to similar to 0 . 05 which is very high for silicates, indicating a complex out-of-equilibrium structure. The minimum apparent activation volume determined from nanoindentation experiments corresponds to Mg and Fe atomic metallic sites in the (Mg,Fe)(2)SiO4 crystalline lattice. The ambient temperature creep behavior of the amorphous olivine films differs very much from the one of single crystal olivine. This behavior directly connects to the recent demonstration of the activation of grain boundary sliding in polycrystalline olivine following grain boundary amorphization under high-stress. (C) 2021 The Authors. Published by Elsevier Ltd on behalf of Acta Materialia Inc.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
DOI: 10.1016/J.ACTAMAT.2021.117257
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“Non-conventional vortex configurations in a mesoscopic flat disk”. Barba-Ortega J, Sardella E, Aguiar JA, Peeters FM, Physica: C : superconductivity 487, 47 (2013). http://doi.org/10.1016/j.physc.2013.01.021
Abstract: The influence of superficial defects on the vortex configurations of a thin superconducting disk is investigated within the time dependent Ginzburg-Landau formalism. The free energy, magnetization, vorticity, and the Cooper pair density are calculated for both metastable and stable vortex configurations and different number of defects on its surface in the presence of an external magnetic field applied perpendicular to the disk area. We show that the competition between the confinement geometry and the geometric position of the defects leads to non-conventional vortex configurations which are not compatible with the symmetry of the sample geometry. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.404
Times cited: 17
DOI: 10.1016/j.physc.2013.01.021
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Barbier M (2012) Transport properties of nanostructures and superlattices on single-layer and bilayer graphene. Antwerpen
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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“Snake states and Klein tunneling in a graphene Hall bar with a pn-junction”. Barbier M, Papp G, Peeters FM, Applied physics letters 100, 163121 (2012). http://doi.org/10.1063/1.4704667
Abstract: The Hall (R-H) and bend (R-B) resistances of a graphene Hall bar structure containing a pn-junction are calculated when in the ballistic regime. The simulations are done using the billiard model. Introducing a pn-junction-dividing the Hall bar geometry in two regions-leads to two distinct regimes exhibiting very different physics: (1) both regions are of n-type and (2) one region is n-type and the other p-type. In regime (1), a “Hall plateau”-an enhancement of the resistance-appears for R-H. On the other hand, in regime (2), we found a negative R-H, which approaches zero for large B. The bend resistance is highly asymmetric in regime (2) and the resistance increases with increasing magnetic field B in one direction while it reduces to zero in the other direction. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4704667]
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 20
DOI: 10.1063/1.4704667
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“Dirac and Klein-Gordon particles in one-dimensional periodic potentials”. Barbier M, Peeters FM, Vasilopoulos P, Milton Pereira J, Physical review : B : condensed matter and materials physics 77, 115446 (2008). http://doi.org/10.1103/PhysRevB.77.115446
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 191
DOI: 10.1103/PhysRevB.77.115446
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“Dirac electrons in a Kronig-Penney potential: dispersion relation and transmission periodic in the strength of the barriers”. Barbier M, Vasilopoulos P, Peeters FM, Physical review : B : solid state 80, 205415 (2009). http://doi.org/10.1103/PhysRevB.80.205415
Abstract: The transmission T and conductance G through one or multiple one-dimensional, ä-function barriers of two-dimensional fermions with a linear energy spectrum are studied. T and G are periodic functions of the strength P of the ä-function barrier V(x,y)/ℏvF=Pä(x). The dispersion relation of a Kronig-Penney (KP) model of a superlattice is also a periodic function of P and causes collimation of an incident electron beam for P=2ðn and n integer. For a KP superlattice with alternating sign of the height of the barriers the Dirac point becomes a Dirac line for P=(n+1/2)ð.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 93
DOI: 10.1103/PhysRevB.80.205415
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“Extra Dirac points in the energy spectrum for superlattices on single-layer graphene”. Barbier M, Vasilopoulos P, Peeters FM, Physical review : B : condensed matter and materials physics 81, 075438 (2010). http://doi.org/10.1103/PhysRevB.81.075438
Abstract: We investigate the emergence of extra Dirac points in the electronic structure of a periodically spaced barrier system, i.e., a superlattice, on single-layer graphene, using a Dirac-type Hamiltonian. Using square barriers allows us to find analytic expressions for the occurrence and location of these new Dirac points in k space and for the renormalization of the electron velocity near them in the low-energy range. In the general case of unequal barrier and well widths the new Dirac points move away from the Fermi level and for given heights of the potential barriers there is a minimum and maximum barrier width outside of which the new Dirac points disappear. The effect of these extra Dirac points on the density of states and on the conductivity is investigated.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 211
DOI: 10.1103/PhysRevB.81.075438
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“Kronig-Penney model on bilayer graphene : spectrum and transmission periodic in the strength of the barriers”. Barbier M, Vasilopoulos P, Peeters FM, Physical review : B : condensed matter and materials physics 82, 235408 (2010). http://doi.org/10.1103/PhysRevB.82.235408
Abstract: We show that the transmission through single and double δ-function potential barriers of strength P=VWb/ℏvF in bilayer graphene is periodic in P with period π. For a certain range of P values we find states that are bound to the potential barrier and that run along the potential barrier. Similar periodic behavior is found for the conductance. The spectrum of a periodic succession of δ-function barriers (Kronig-Penney model) in bilayer graphene is periodic in P with period 2π. For P smaller than a critical value Pc, the spectrum exhibits two Dirac points while for P larger than Pc an energy gap opens. These results are extended to the case of a superlattice of δ-function barriers with P alternating in sign between successive barriers; the corresponding spectrum is periodic in P with period π.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 34
DOI: 10.1103/PhysRevB.82.235408
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“Single-layer and bilayer graphene superlattices: collimation, additional Dirac points and Dirac lines”. Barbier M, Vasilopoulos P, Peeters FM, Philosophical transactions of the Royal Society : mathematical, physical and engineering sciences 368, 5499 (2010). http://doi.org/10.1098/rsta.2010.0218
Abstract: We review the energy spectrum and transport properties of several types of one-dimensional superlattices (SLs) on single-layer and bilayer graphene. In single-layer graphene, for certain SL parameters an electron beam incident on an SL is highly collimated. On the other hand, there are extra Dirac points generated for other SL parameters. Using rectangular barriers allows us to find analytical expressions for the location of new Dirac points in the spectrum and for the renormalization of the electron velocities. The influence of these extra Dirac points on the conductivity is investigated. In the limit of δ-function barriers, the transmission T through and conductance G of a finite number of barriers as well as the energy spectra of SLs are periodic functions of the dimensionless strength P of the barriers, Graphic, with vF the Fermi velocity. For a KronigPenney SL with alternating sign of the height of the barriers, the Dirac point becomes a Dirac line for P = π/2+nπ with n an integer. In bilayer graphene, with an appropriate bias applied to the barriers and wells, we show that several new types of SLs are produced and two of them are similar to type I and type II semiconductor SLs. Similar to single-layer graphene SLs, extra Dirac points are found in bilayer graphene SLs. Non-ballistic transport is also considered.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.97
Times cited: 64
DOI: 10.1098/rsta.2010.0218
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“Band structure, density of states, and transmission in graphene bilayer superlattices”. Barbier M, Vasilopoulos P, Peeters FM, Pereira JM, AIP conference proceedings 1199, 547 (2009). http://doi.org/10.1063/1.3295550
Abstract: The energy spectrum and density of states of graphene bilayer superlattices (SLs) are evaluated. We take into account doping and/or gating of the layers as well as tunnel coupling between them. In addition, we evaluate the transmission through such SLs and through single or double barriers. The transmission exhibits a strong dependence on the direction of the incident wave vector.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
DOI: 10.1063/1.3295550
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“Bilayer graphene with single and multiple electrostatic barriers: band structure and transmission”. Barbier M, Vasilopoulos P, Peeters FM, Pereira JM, Physical review : B : solid state 79, 155402 (2009). http://doi.org/10.1103/PhysRevB.79.155402
Abstract: We evaluate the electronic transmission and conductance in bilayer graphene through a finite number of potential barriers. Further, we evaluate the dispersion relation in a bilayer graphene superlattice with a periodic potential applied to both layers. As a model we use the tight-binding Hamiltonian in the continuum approximation. For zero bias the dispersion relation shows a finite gap for carriers with zero momentum in the direction parallel to the barriers. This is in contrast to single-layer graphene where no such gap was found. A gap also appears for a finite bias. Numerical results for the energy spectrum, conductance, and the density of states are presented and contrasted with those pertaining to single-layer graphene.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 74
DOI: 10.1103/PhysRevB.79.155402
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“Sol-gel hot injection synthesis of ZnO nanoparticles into a porous silica matrix and reaction mechanism”. Barhoum A, Van Assche G, Rahier H, Fleisch M, Bals S, Delplancked M-P, Leroux F, Bahnemann D, Materials &, design 119, 270 (2017). http://doi.org/10.1016/J.MATDES.2017.01.059
Abstract: Despite the enormous interest in the properties and applications of porous silica matrix, only a few attempts have been reported to deposit metal and metal oxide nanoparticles (NPs) inside the porous silica matrix. We report a simple approach (i.e. sol-gel hot injection) for insitu synthesis of ZnO NPs inside a porous silica matrix. Control of the Zn:Si molar ratio, reaction temperature, pH value, and annealing temperature permits formation of ZnO NPs (<= 10 nm) inside a porous silica particles, without additives or organic solvents. Results revealed that a solid state reaction inside the ZnO/SiO2 nanocomposites occurs with increasing the annealing temperature. The reaction of ZnO NPs with SiO2 matrix was insignificant up to approximately 500 degrees C. However, ZnO NPs react strongly with the silica matrix when the nanocomposites are annealed at temperatures above 700 degrees C. Extensive annealing of the ZnO/SiO2 nanocomposite at 900 degrees C yields 3D structures made of 500 nm rod-like, 5-7 pm tube-like and 35 pm needle-like Zn2SiO4 crystals. A possible mechanism for forming ZnO NPs inside porous silica matrix and phase transformation of the ZnO/SiO2 nanocomposites into 3D architectures of Zn2SiO4 are carefully discussed. (C) 2017 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.364
Times cited: 43
DOI: 10.1016/J.MATDES.2017.01.059
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“Barium-based manganites Ln1-xBaxMnO3 with Ln = {Pr, La}: phase transitions and magnetoresistance properties”. Barnabé, A, Millange F, Maignan A, Hervieu M, Raveau B, Van Tendeloo G, Laffez P, Chem. mater. 10, 252 (1998). http://doi.org/10.1021/cm9704084
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 48
DOI: 10.1021/cm9704084
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“The observation and theory of optically detected magnetophonon resonance”. Barnes DJ, Nicholas RJ, Peeters FM, Wu XG, Devreese JT, Singleton J, Langerak CJGM, Harris JJ, Foxon CT, Physical review letters 66, 794 (1991)
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Theory of quantum systems and complex systems
Impact Factor: 7.512
Times cited: 38
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“Optically detected magnetophonon resonance in GaAs-GaAlAs heterojunctions”. Barnes DJ, Nicholas RJ, Watts M, Peeters FM, Wu XG, Devreese JT, Langerak CJ, Singleton J, Harris JJ, Foxon CT, (1991)
Keywords: P3 Proceeding; Condensed Matter Theory (CMT); Theory of quantum systems and complex systems
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“Fe2O3-TiO2Nano-heterostructure Photoanodes for Highly Efficient Solar Water Oxidation”. Barreca D, Carraro G, Gasparotto A, Maccato C, Warwick MEA, Kaunisto K, Sada C, Turner S, Gönüllü, Y, Ruoko T-P, Borgese L, Bontempi E, Van Tendeloo G, Lemmetyinen H, Mathur S, Advanced Materials Interfaces 2, 1500313 (2015). http://doi.org/10.1002/admi.201500313
Abstract: Harnessing solar energy for the production of clean hydrogen by photoelectrochemical water splitting represents a very attractive, but challenging approach for sustainable energy generation. In this regard, the fabrication of Fe2O3–TiO2 photoanodes is reported, showing attractive performances [≈2.0 mA cm−2 at 1.23 V vs. the reversible hydrogen electrode in 1 M NaOH] under simulated one-sun illumination. This goal, corresponding to a tenfold photoactivity enhancement with respect to bare Fe2O3, is achieved by atomic layer deposition of TiO2 over hematite (α-Fe2O3) nanostructures fabricated by plasma enhanced-chemical vapor deposition and final annealing at 650 °C. The adopted approach enables an intimate Fe2O3–TiO2 coupling, resulting in an electronic interplay at the Fe2O3/TiO2 interface. The reasons for the photocurrent enhancement determined by TiO2 overlayers with increasing thickness are unraveled by a detailed chemico-physical investigation, as well as by the study of photogenerated charge carrier dynamics. Transient absorption spectroscopy shows that the increased photoelectrochemical response of heterostructured photoanodes compared to bare hematite is due to an enhanced separation of photogenerated charge carriers and more favorable hole dynamics for water oxidation. The stable responses obtained even in simulated seawater provides a feasible route in view of the eventual large-scale generation of renewable energy.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.279
Times cited: 56
DOI: 10.1002/admi.201500313
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