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“Synthesis of Janus plasmonic-magnetic, star-sphere nanoparticles, and their application in SERS detection”. Reguera J, Jiménez de Aberasturi D, Naomi Winckelmans N, Langer J, Bals S, Liz-Marzan LM, Faraday discussions 191, 47 (2016). http://doi.org/10.1039/C6FD00012F
Abstract: Multicomponent nanoparticles are of particular interest due to a unique combination of properties at the nanoscale, which make them suitable for a wide variety of applications. Among them, Janus nanoparticles, presenting two distinct surface regions, can lead to specific interactions with interfaces, biomolecules, membranes etc. We report the synthesis of Janus nanoparticles comprising iron oxide nanospheres and gold nanostars, through two consecutive seed-mediated-growth steps. Electron tomography combining HAADF-STEM and EDX mapping has been performed to evaluate the spatial distribution of the two components of the nanoparticle, showing their clear separation in a Janus morphology. Additionally, SERS measurements assisted by magnetic separation were carried out to assess the application of combined plasmonic and magnetic properties for sensing.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.588
Times cited: 53
DOI: 10.1039/C6FD00012F
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“Division of labor and growth during electrical cooperation in multicellular cable bacteria”. Geerlings NMJ, Karman C, Trashin S, As KS, Kienhuis MVM, Hidalgo-Martinez S, Vasquez-Cardenas D, Boschker HTS, De Wael K, Middelburg JJ, Polerecky L, Meysman FJR, Proceedings Of The National Academy Of Sciences Of The United States Of America 117, 5478 (2020). http://doi.org/10.1073/PNAS.1916244117
Abstract: Multicellularity is a key evolutionary innovation, leading to coordinated activity and resource sharing among cells, which generally occurs via the physical exchange of chemical compounds. However, filamentous cable bacteria display a unique metabolism in which redox transformations in distant cells are coupled via long-distance electron transport rather than an exchange of chemicals. This challenges our understanding of organismal functioning, as the link among electron transfer, metabolism, energy conservation, and filament growth in cable bacteria remains enigmatic. Here, we show that cells within individual filaments of cable bacteria display a remarkable dichotomy in biosynthesis that coincides with redox zonation. Nanoscale secondary ion mass spectrometry combined with 13 C (bicarbonate and propionate) and 15 N-ammonia isotope labeling reveals that cells performing sulfide oxidation in deeper anoxic horizons have a high assimilation rate, whereas cells performing oxygen reduction in the oxic zone show very little or no label uptake. Accordingly, oxygen reduction appears to merely function as a mechanism to quickly dispense of electrons with little to no energy conservation, while biosynthesis and growth are restricted to sulfide-respiring cells. Still, cells can immediately switch roles when redox conditions change, and show no differentiation, which suggests that the “community service” performed by the cells in the oxic zone is only temporary. Overall, our data reveal a division of labor and electrical cooperation among cells that has not been seen previously in multicellular organisms.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 11.1
Times cited: 6
DOI: 10.1073/PNAS.1916244117
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“Control of the outer diameter of thin carbon nanotubes synthesized by catalytic decomposition of hydrocarbons”. Willems I, Konya Z, Colomer JF, Van Tendeloo G, Nagaraju N, Fonseca A, Nagy JB, Chemical physics letters 317, 71 (2000). http://doi.org/10.1016/S0009-2614(99)01300-7
Abstract: Multi-wall carbon nanotubes have been produced by the catalytic decomposition of acetylene. Go-Mo, Co-V and Co-Fe mixtures supported either on zeolite or corundum alumina were used as catalysts. When Fe or V is added to Co, the carbon deposit increases. The nanotubes were characterized by both low and high resolution TEM. From histograms representing the outer diameter distributions, it is clear that the outer diameter of the nanotubes can be controlled by choosing the appropriate catalyst. (C) 2000 Elsevier Science B.V. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.815
Times cited: 130
DOI: 10.1016/S0009-2614(99)01300-7
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“Photoemission study of CF4 rf-plasma treated multi-wall carbon nanotubes”. Felten A, Ghijsen J, Pireaux J-J, Whelan CM, Liang D, Van Tendeloo G, Bittencourt C, Carbon 46, 1271 (2008). http://doi.org/10.1016/j.carbon.2008.04.027
Abstract: Multi-wall carbon nanotubes (MWCNTs) were exposed to a CF4 rf-plasma. X-ray photoelectron spectroscopy analysis shows that the treatment effectively grafts fluorine atoms onto the MWCNTs. The fluorine atomic concentration and the nature of the CF bond (semi-ionic or covalent) can be tuned by varying the exposure time. Ultraviolet photoelectron spectroscopy analysis confirms that the valence electronic states are altered by the grafting of fluorine atoms. Characterization with high-resolution transmission electron microscopy reveals that while the plasma treatment does not induce significant etching impact on the CNT-surface, it does increase the number of active sites for gold cluster formation.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 6.337
Times cited: 21
DOI: 10.1016/j.carbon.2008.04.027
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“Spectroscopy and defect identification for fluorinated carbon nanotubes”. Bittencourt C, van Lier G, Ke X, Suarez-Martinez I, Felten A, Ghijsen J, Van Tendeloo G, Ewels CO, ChemPhysChem : a European journal of chemical physics and physical chemistry 10, 920 (2009). http://doi.org/10.1002/cphc.200800851
Abstract: Multi-wall carbon nanotubes (MWCNTs) were exposed to a CF4 radio-frequency (rf) plasma. High-resolution photoelectron spectroscopy shows that the treatment effectively grafts fluorine atoms onto the MWCNTs, altering the valence electronic states. Fluorine surface concentration can be tuned by varying the exposure time. Evaporation of gold onto MWCNTs is used to mark active site formation. High-resolution transmission electron microscopy coupled with density functional theory (DFT) modelling is used to characterise the surface defects formed, indicating that the plasma treatment does not etch the tube surface. We suggest that this combination of theory and microscopy of thermally evaporated gold atoms onto the CNT surface may be a powerful approach to characterise both surface defect density as well as defect type.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.075
Times cited: 14
DOI: 10.1002/cphc.200800851
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“Metallic nanoparticles on plasma treated carbon nanotubes : $Nano2hybrids$”. Bittencourt C, Felten A, Douhard B, Colomer J-F, Van Tendeloo G, Drube W, Ghijsen J, Pireaux J-J, Surface science : a journal devoted to the physics and chemistry of interfaces
T2 –, International Conference on NANO-Structures Self Assembling, JUL 02-06, 2006, Aix en Provence, FRANCE 601, 2800 (2007). http://doi.org/10.1016/j.susc.2006.12.045
Abstract: Multi-wall carbon nanotubes (MWCNTs) were decorated with metal clusters by thermal evaporation. Transmission electron microscopy (TEM) shows that the nature and extent of metal coverage can be varied by plasma treating the MWCNT surface. The metal clusters on oxygen plasma treated arc-discharge MWCNTs have a more dense distribution than the clusters evaporated on as-synthesized are-discharge MWCNTs. In contrast, the plasma treatment did not affect the cluster distribution on CVD MWCNTs. Analyses of the valence band and the core levels by X-ray photoelectron spectroscopy suggest poor charge transfer between gold clusters and MWCNTs; on the contrary suggest good charge transfer between Ni clusters and MWCNTs. (c) 2007 Elsevier B. V. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.062
Times cited: 44
DOI: 10.1016/j.susc.2006.12.045
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“A Pareto aggregation approach for environmental-economic multi-objective optimization applied on a second-generation bioethanol production model”. Vasilakou K, Billen P, Van Passel S, Nimmegeers P, Energy conversion and management 303, 118184 (2024). http://doi.org/10.1016/J.ENCONMAN.2024.118184
Abstract: Multi-objective optimization is an important decision-making tool for energy processes, as multiple targets need to be achieved. These objectives are usually conflicting since a single solution cannot be optimal for all objectives, resulting in a set of Pareto-optimal solutions. Multiple indicators might be available to describe a sustainability objective, such as the environmental impact which is commonly evaluated by performing a life cycle assessment. In this study, Pareto aggregation is proposed as a method which employs a novel multi-objective optimization-based approach as an alternative to the classically used aggregation in life cycle assessment. This method identifies conflicting environmental indicators and performs an aggregation among those that require a trade-off. An environmental-economic optimization of a second-generation bioethanol plant is used to illustrate and evaluate the proposed method. Process parameters from a biochemical conversion pathway flowsheet simulation model are chosen as optimization variables. To reduce the computational time, surrogate models, based on artificial neural networks, are used. Out of the eighteen ReCiPe Midpoint environmental indicators, five were identified as conflicting, resulting in an aggregated environmental objective, which was then traded off with the economic objective function, chosen as the levelized cost of ethanol. Comparison with the widely used single-score EcoIndicator99 showed that the Pareto aggregation method can reduce most of the environmental indicators by up to 6.5%. This research provides an insight on non-redundant objective functions, aiming at reducing the dimensionality of multi-objective optimization problems, while taking into consideration decision-makers’ preferences.
Keywords: A1 Journal article; Economics; Engineering sciences. Technology; Engineering Management (ENM); Intelligence in PRocesses, Advanced Catalysts and Solvents (iPRACS)
Impact Factor: 10.4
DOI: 10.1016/J.ENCONMAN.2024.118184
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“Metal pollution and selenium distributions in soils and grass near a non-ferrous plant”. Robberecht H, Deelstra H, vanden Berghe D, Van Grieken R, The science of the total environment 29, 229 (1983). http://doi.org/10.1016/0048-9697(83)90093-1
Abstract: Multi-element analysis results of direct energy-dispersive X-ray fluorescence of soil samples taken in the vicinity of a non-ferrous plant in Antwerp are reported. High concentrations of Pb, Cu, Zn, As and Se are found in nearby residential areas, especially in top-soil layers. Selenium pollution appears not to be leached significantly to lower soil horizons, but it is available for uptake by rye-grass, in which toxic levels are found. Results are compared to literature data. Hydride generation atomic absorption spectrometry proved to be unsuitable for direct analysis of the heavily contaminated soils.
Keywords: A1 Journal article; Pharmacology. Therapy; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/0048-9697(83)90093-1
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“Synchrotron radiation induced X-ray microfluorescence analysis”. Janssens K, Vincze L, Vekemans B, Aerts A, Adams F, Jones KW, Knöchel A, Microchimica acta
T2 –, 4th Workshop of the European-Microanalysis-Society on Modern, Developments and Applications in Microbeam Analysis, MAY, 1995, ST MALO, FRANCE , 87 (1996)
Abstract: mu-XRF is the microscopic equivalent of the well-established multielement analytical technique. In this paper, after comparing the interaction of X-ray photons, electrons and protons with matter and an introduction to synchrotron rings and microfocussing of X-rays, the instrumentation for mu-XRF is discussed, both for laboratory source and synchrotron based setups and the analytical characteristics of mu-XRF are contrasted to that of other microanalytical techniques, Also, this issue of quantification of mu-XRF data is addressed; the applicability of the method in archeological and geological analysis is illustrated.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“Fluctuations in superconducting rings with two order parameters”. Berger J, Milošević, MV, Physical review : B : condensed matter and materials physics 84, 214515 (2011). http://doi.org/10.1103/PhysRevB.84.214515
Abstract: Motivated by two-band superconductivity in, e.g., borides and pnictides, starting from the two-band Ginzburg-Landau energy functional, we discuss how the presence of two order parameters and the coupling between them influence a superconducting ring in the fluctuative regime. Our method is an extension of the von OppenRiedel formalism for rings; it is exact, but requires numerical implementation. We also study approximations for which analytic expressions can be obtained, and check their ranges of validity. We provide estimates for the temperature ranges where fluctuations are important, calculate the persistent current in MgB2 rings as a function of temperature and enclosed flux, and point out its additional dependence on the cross-section area of the wire from which the ring is made. We find temperature regions in which fluctuations enhance the persistent currents and regions where they inhibit the persistent current. The presence of two order parameters that can fluctuate independently always leads to larger averages of the order parameters at Tc, but yields larger persistent current only for appropriate parameters. In cases of very different material parameters for the two coupled condensates, the persistent current is inhibited.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 7
DOI: 10.1103/PhysRevB.84.214515
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“A van der Waals heterostructure of MoS₂/MoSi₂N₄, : a first-principles study”. Bafekry A, Faraji M, Ziabari AA, Fadlallah MM, Nguyen C V, Ghergherehchi M, Feghhi SAH, New Journal Of Chemistry 45, 8291 (2021). http://doi.org/10.1039/D1NJ00344E
Abstract: Motivated by the successful preparation of MoSi2N4 monolayers in the last year [Y.-L. Hong et al., Science, 2020, 369, 670-674], we investigate the structural, electronic and optical properties of the MoS2/MoSi2N4 heterostructure (HTS). The phonon dispersion and the binding energy calculations refer to the stability of the HTS. The heterostructure has an indirect bandgap of 1.26 (1.84) eV using PBE (HSE06) which is smaller than the corresponding value of MoSi2N4 and MoS2 monolayers. We find that the work function of the MoS2/MoSi2N4 HTS is smaller than the corresponding value of its individual monolayers. The heterostructure structure can enhance the absorption of light spectra not only in the ultraviolet region but also in the visible region as compared to MoSi2N4 and MoS2 monolayers. The refractive index behaviour of the HTS can be described as the cumulative effect which is well described in terms of a combination of the individual effects (the refractive index of MoSi2N4 and MoS2 monolayers).
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.269
DOI: 10.1039/D1NJ00344E
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“Vanadium dopant- and strain-dependent magnetic properties of single-layer VI₃”. Baskurt M, Eren I, Yagmurcukardes M, Sahin H, Applied Surface Science 508, 144937 (2020). http://doi.org/10.1016/J.APSUSC.2019.144937
Abstract: Motivated by the recent synthesis of two-dimensional VI3 [Kong et al. Adv. Mater. 31, 1808074 (2019)], we investigate the effect of V doping on the magnetic and electronic properties of monolayer VI3 by means of first-principles calculations. The dynamically stable semiconducting ferromagnetic (FM) and antiferromagnetic (AFM) phases of monolayer VI3 are found to display distinctive vibrational features that the magnetic state can be distinguished by Raman spectroscopy. In order to clarify the effect of experimentally observed excessive V atoms, the magnetic and electronic properties of the V-doped VI3 structures are analyzed. Our findings indicate that partially doped VI3 structures display FM ground state while the fully-doped structure exhibits AFM ground state. The fully-doped monolayer VI3 is found to be a semiconductor with a relatively larger band gap than its pristine structure. In addition, strain-dependent electronic and magnetic properties of fully- and partially-doped VI3 structures reveal that pristine monolayer displays a FM-to-AFM phase transition with robust semiconducting nature for 5% of compressive strain, while fully-doped monolayer VI3 structure possesses AFM-to-FM semiconducting transition at tensile strains larger than 4%. In contrast, the partially-doped VI3 monolayers are found to display robust FM ground state under biaxial strain. Its dopant and strain tunable electronic and magnetic nature makes monolayer VI3 a promising material for applications in nanoscale spintronic devices.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 6.7
Times cited: 10
DOI: 10.1016/J.APSUSC.2019.144937
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“Hematite at its thinnest limit”. Bacaksiz C, Yagmurcukardes M, Peeters FM, Milošević, MV, 2d Materials 7, 025029 (2020). http://doi.org/10.1088/2053-1583/AB6D79
Abstract: Motivated by the recent synthesis of two-dimensional alpha-Fe2O3 (Balan et al 2018 Nat. Nanotechnol. 13 602), we analyze the structural, vibrational, electronic and magnetic properties of single- and few-layer alpha-Fe2O3 compared to bulk, by ab initio and Monte-Carlo simulations. We reveal how monolayer alpha-Fe2O3 (hematene) can be distinguished from the few-layer structures, and how they all differ from bulk through observable Raman spectra. The optical spectra exhibit gradual shift of the prominent peak to higher energy, as well as additional features at lower energy when alpha-Fe2O3 is thinned down to a monolayer. Both optical and electronic properties have strong spin asymmetry, meaning that lower-energy optical and electronic activities are allowed for the single-spin state. Finally, our considerations of magnetic properties reveal that 2D hematite has anti-ferromagnetic ground state for all thicknesses, but the critical temperature for Morin transition increases with decreasing sample thickness. On all accounts, the link to available experimental data is made, and further measurements are prompted.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 5.5
Times cited: 12
DOI: 10.1088/2053-1583/AB6D79
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“Electronic and magnetic properties of 1T-TiSe2 nanoribbons”. Ozaydin HD, Sahin H, Kang J, Peeters FM, Senger RT, 2D materials 2, 044002 (2015). http://doi.org/10.1088/2053-1583/2/4/044002
Abstract: Motivated by the recent synthesis of single layer TiSe2, we used state-of-the-art density functional theory calculations, to investigate the structural and electronic properties of zigzag and armchair-edged nanoribbons (NRs) of this material. Our analysis reveals that, differing from ribbons of other ultra-thin materials such as graphene, TiSe2 NRs have some distinctive properties. The electronic band gap of the NRs decreases exponentially with the width and vanishes for ribbons wider than 20 angstrom. For ultranarrow zigzag-edged NRs we find odd-even oscillations in the band gap width, although their band structures show similar features. Moreover, our detailed magnetic-ground-state analysis reveals that zigzag and armchair edged ribbons have non-magnetic ground states. Passivating the dangling bonds with hydrogen at the edges of the structures influences the band dispersion. Our results shed light on the characteristic properties of T phase NRs of similar crystal structures.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 6.937
Times cited: 20
DOI: 10.1088/2053-1583/2/4/044002
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“Graphene hetero-multilayer on layered platinum mineral Jacutingaite (Pt₂HgSe₃): Van der Waals heterostructures with novel optoelectronic and thermoelectric performances”. Bafekry A, Obeid M, Nguyen C, Bagheri Tagani M, Ghergherehchi M, Journal Of Materials Chemistry A 8, 13248 (2020). http://doi.org/10.1039/D0TA02847A
Abstract: Motivated by the recent successful synthesis of the layered platinum mineral jacutingaite (Pt2HgSe3), we have studied the optoelectronic, mechanical, and thermoelectric properties of graphene hetero-multilayer on Pt(2)HgSe(3)monolayer (PHS) heterostructures (LG/PHS) by using first-principles calculations. PHS is a topological insulator with a band gap of about 160 meV with fully relativistic calculations; when graphene layers are stacked on PHS, a narrow band gap of similar to 10-15 meV opens. In the presence of gate-voltage and out-of plane strain,i.e.pressure, the electronic properties are modified; the Dirac-cone of graphene can be shifted upwards (downward) to a lower (higher) binding energy. The absorption spectrum shows two peaks, which are located around 216 nm (5.74 eV) and protracted to 490 nm (2.53 eV), indicating that PHS could absorb more visible light. Increasing the number of graphene layers on PHS has a positive impact on the UV-vis light absorption and gives a clear red-shift with enhanced absorption intensity. To investigate the electronic performance of the heterostructure, the electrical conductance and thermopower of a device composed of graphene layers and PHS is examined by a combination of DFT and Green function formalism. The number of graphene layers can significantly tune the thermopower and electrical conductance. This analysis reveals that the heterostructures not only significantly affect the electronic properties, but they can also be used as an efficient way to modulate the optic and thermoelectric properties.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 11.9
Times cited: 20
DOI: 10.1039/D0TA02847A
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“Two-dimensional Janus semiconductor BiTeCl and BiTeBr monolayers : a first-principles study on their tunable electronic properties via an electric field and mechanical strain”. Bafekry A, Karbasizadeh S, Stampfl C, Faraji M, Hoat DM, Sarsari IA, Feghhi SAH, Ghergherehchi M, Physical Chemistry Chemical Physics 23, 15216 (2021). http://doi.org/10.1039/D1CP01368H
Abstract: Motivated by the recent successful synthesis of highly crystalline ultrathin BiTeCl and BiTeBr layered sheets [Debarati Hajra et al., ACS Nano, 2020, 14, 15626], herein for the first time, we carry out a comprehensive study on the structural and electronic properties of BiTeCl and BiTeBr Janus monolayers using density functional theory (DFT) calculations. Different structural and electronic parameters including the lattice constant, bond lengths, layer thickness in the z-direction, different interatomic angles, work function, charge density difference, cohesive energy and Rashba coefficients are determined to acquire a deep understanding of these monolayers. The calculations show good stability of the studied single layers. BiTeCl and BiTeBr monolayers are semiconductors with electronic bandgaps of 0.83 and 0.80 eV, respectively. The results also show that the semiconductor-metal transformation can be induced by increasing the number of layers. In addition, the engineering of the electronic structure is also studied by applying an electric field, and mechanical uniaxial and biaxial strain. The results show a significant change of the bandgaps and that an indirect-direct band-gap transition can be induced. This study highlights the positive prospect for the application of BiTeCl and BiTeBr layered sheets in novel electronic and energy conversion systems.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 4.123
DOI: 10.1039/D1CP01368H
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“Strain and electric field tuning of semi-metallic character WCrCO₂, MXenes with dual narrow band gap”. Bafekry A, Akgenc B, Ghergherehchi M, Peeters FM, Journal Of Physics-Condensed Matter 32, 355504 (2020). http://doi.org/10.1088/1361-648X/AB8E88
Abstract: Motivated by the recent successful synthesis of double-M carbides, we investigate structural and electronic properties of WCrC and WCrCO2 monolayers and the effects of biaxial and out-of-plane strain and electric field using density functional theory. WCrC and WCrCO2 monolayers are found to be dynamically stable. WCrC is metallic and WCrCO2 display semi-metallic character with narrow band gap, which can be controlled by strain engineering and electric field. WCrCO2 monolayer exhibits a dual band gap which is preserved in the presence of an electric field. The band gap of WCrCO2 monolayer increases under uniaxial strain while it becomes metallic under tensile strain, resulting in an exotic 2D double semi-metallic behavior. Our results demonstrate that WCrCO2 is a new platform for the study of novel physical properties in two-dimensional Dirac materials and which may provide new opportunities to realize high-speed low-dissipation devices.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.7
Times cited: 45
DOI: 10.1088/1361-648X/AB8E88
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“Adsorption of H2O, NH3, CO, NO2, and NO on graphene: a first-principles study”. Leenaerts O, Partoens B, Peeters FM, Physical review : B : condensed matter and materials physics 77, 125416 (2008). http://doi.org/10.1103/PhysRevB.77.125416
Abstract: Motivated by the recent realization of graphene sensors to detect individual gas molecules, we investigate the adsorption of H2O, NH3, CO, NO2, and NO on a graphene substrate using first-principles calculations. The optimal adsorption position and orientation of these molecules on the graphene surface is determined and the adsorption energies are calculated. Molecular doping, i.e., charge transfer between the molecules and the graphene surface, is discussed in light of the density of states and the molecular orbitals of the adsorbates. The efficiency of doping of the different molecules is determined and the influence of their magnetic moment is discussed.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 1392
DOI: 10.1103/PhysRevB.77.125416
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“A Dirac-semimetal two-dimensional BeN4 : thickness-dependent electronic and optical properties”. Bafekry A, Stampfl C, Faraji M, Yagmurcukardes M, Fadlallah MM, Jappor HR, Ghergherehchi M, Feghhi SAH, Applied Physics Letters 118, 203103 (2021). http://doi.org/10.1063/5.0051878
Abstract: Motivated by the recent experimental realization of a two-dimensional (2D) BeN4 monolayer, in this study we investigate the structural, dynamical, electronic, and optical properties of a monolayer and few-layer BeN4 using first-principles calculations. The calculated phonon band dispersion reveals the dynamical stability of a free-standing BeN4 layer, while the cohesive energy indicates the energetic feasibility of the material. Electronic band dispersions show that monolayer BeN4 is a semi-metal whose conduction and valence bands touch each other at the Sigma point. Our results reveal that increasing the layer number from single to six-layers tunes the electronic nature of BeN4. While monolayer and bilayer structures display a semi-metallic behavior, structures thicker than that of three-layers exhibit a metallic nature. Moreover, the optical parameters calculated for monolayer and bilayer structures reveal that the bilayer can absorb visible light in the ultraviolet and visible regions better than the monolayer structure. Our study investigates the electronic properties of Dirac-semimetal BeN4 that can be an important candidate for applications in nanoelectronic and optoelectronic. Published under an exclusive license by AIP Publishing.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
DOI: 10.1063/5.0051878
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“Stacking-dependent topological magnons in bilayer CrI₃”. Soenen M, Bacaksiz C, Menezes RM, Milošević, MV, Physical review materials 7, 024421 (2023). http://doi.org/10.1103/PHYSREVMATERIALS.7.024421
Abstract: Motivated by the potential of atomically thin magnets towards achieving tunable high-frequency magnonics, we detail the spin-wave dispersion of bilayer CrI3. We demonstrate that the magnonic behavior of the bilayer strongly depends on its stacking configuration and the interlayer magnetic ordering, where a topological band gap opens in the dispersion caused by the Dzyaloshinskii-Moriya and Kitaev interactions, classifying bilayer CrI3 as a topological magnon insulator. We further reveal that both the size and the topology of the band gap in a CrI3 bilayer with an antiferromagnetic interlayer ordering are tunable by an external magnetic field.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.4
DOI: 10.1103/PHYSREVMATERIALS.7.024421
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“Homogeneous flow and size dependent mechanical behavior in highly ductile Zr 65 Ni 35 metallic glass films”. Ghidelli M, Idrissi H, Gravier S, Blandin J-J, Raskin J-P, Schryvers D, Pardoen T, Acta materialia 131, 246 (2017). http://doi.org/10.1016/j.actamat.2017.03.072
Abstract: Motivated by recent studies demonstrating a high strength – high ductility potential of nano-scale metallic glass samples, the mechanical response of freestanding Zr65Ni35 film with sub-micron thickness has been investigated by combining advanced on-chip tensile testing and electron microscopy. Large deformation up to 15% is found for specimen thicknesses below 500 nm with variations depending on specimen size and frame compliance. The deformation is homogenous until fracture, with no evidence of shear banding. The yield stress is doubled when decreasing the specimen cross-section, reaching ~3 GPa for small cross-sections. The fracture strain variation is related to both the stability of the test device and to the specimen size. The study concludes on clear disconnect between the mechanisms controlling the onset of plasticity and the fracture process.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
Times cited: 42
DOI: 10.1016/j.actamat.2017.03.072
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“Phonon softening and direct to indirect band gap crossover in strained single-layer MoSe2”. Horzum S, Sahin H, Cahangirov S, Cudazzo P, Rubio A, Serin T, Peeters FM, Physical review : B : condensed matter and materials physics 87, 125415 (2013). http://doi.org/10.1103/PhysRevB.87.125415
Abstract: Motivated by recent experimental observations of Tongay et al. [Nano Lett. 12, 5576 (2012)] we show how the electronic properties and Raman characteristics of single layer MoSe2 are affected by elastic biaxial strain. We found that with increasing strain: (1) the E' and E '' Raman peaks (E-2g and E-1g in bulk) exhibit significant redshifts (up to similar to 30 cm(-1)), (2) the position of the A'(1) peak remains at similar to 180 cm(-1) (A(1g) in bulk) and does not change considerably with further strain, (3) the dispersion of low energy flexural phonons crosses over from quadratic to linear, and (4) the electronic band structure undergoes a direct to indirect band gap crossover under similar to 3% biaxial tensile strain. Thus the application of strain appears to be a promising approach for a rapid and reversible tuning of the electronic, vibrational, and optical properties of single layer MoSe2 and similar MX2 dichalcogenides. DOI:10.1103/PhysRevB.87.125415
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 171
DOI: 10.1103/PhysRevB.87.125415
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“Nitrogenated, phosphorated and arsenicated monolayer holey graphenes”. Yagmurcukardes M, Horzum S, Torun E, Peeters FM, Senger RT, Physical chemistry, chemical physics 18, 3144 (2016). http://doi.org/10.1039/c5cp05538e
Abstract: Motivated by a recent experiment that reported the synthesis of a new 2D material nitrogenated holey graphene (C2N) [Mahmood et al., Nat. Commun., 2015, 6, 6486], the electronic, magnetic, and mechanical properties of nitrogenated (C2N), phosphorated (C2P) and arsenicated (C2As) monolayer holey graphene structures are investigated using first-principles calculations. Our total energy calculations indicate that, similar to the C2N monolayer, the formation of the other two holey structures are also energetically feasible. Calculated cohesive energies for each monolayer show a decreasing trend going from the C2N to C2As structure. Remarkably, all the holey monolayers considered are direct band gap semiconductors. Regarding the mechanical properties (in-plane stiffness and Poisson ratio), we find that C2N has the highest in-plane stiffness and the largest Poisson ratio among the three monolayers. In addition, our calculations reveal that for the C2N, C2P and C2As monolayers, creation of N and P defects changes the semiconducting behavior to a metallic ground state while the inclusion of double H impurities in all holey structures results in magnetic ground states. As an alternative to the experimentally synthesized C2N, C2P and C2As are mechanically stable and flexible semiconductors which are important for potential applications in optoelectronics.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 4.123
Times cited: 36
DOI: 10.1039/c5cp05538e
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“Hexagonal A1N : dimensional-crossover-driven band-gap transition”. Bacaksiz C, Sahin H, Ozaydin HD, Horzum S, Senger RT, Peeters FM, Physical review : B : condensed matter and materials physics 91, 085430 (2015). http://doi.org/10.1103/PhysRevB.91.085430
Abstract: Motivated by a recent experiment that reported the successful synthesis of hexagonal (h) AlN [Tsipas et al., Appl. Phys. Lett. 103, 251605 (2013)], we investigate structural, electronic, and vibrational properties of bulk, bilayer, and monolayer structures of h-AlN by using first-principles calculations. We show that the hexagonal phase of the bulk h-AlN is a stable direct-band-gap semiconductor. The calculated phonon spectrum displays a rigid-layer shear mode at 274 cm(-1) and an E-g mode at 703 cm(-1), which are observable by Raman measurements. In addition, single-layer h-AlN is an indirect-band-gap semiconductor with a nonmagnetic ground state. For the bilayer structure, AA'-type stacking is found to be the most favorable one, and interlayer interaction is strong. While N-layered h-AlN is an indirect-band-gap semiconductor for N = 1 – 9, we predict that thicker structures (N >= 10) have a direct band gap at the Gamma point. The number-of-layer-dependent band-gap transitions in h-AlN is interesting in that it is significantly different from the indirect-to-direct crossover obtained in the transition-metal dichalcogenides.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 99
DOI: 10.1103/PhysRevB.91.085430
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“Two-dimensional covalent crystals by chemical conversion of thin van der Waals materials”. Sreepal V, Yagmurcukardes M, Vasu KS, Kelly DJ, Taylor SFR, Kravets VG, Kudrynskyi Z, Kovalyuk ZD, Patane A, Grigorenko AN, Haigh SJ, Hardacre C, Eaves L, Sahin H, Geim AK, Peeters FM, Nair RR, Nano letters 19, 6475 (2019). http://doi.org/10.1021/ACS.NANOLETT.9B02700
Abstract: Most of the studied two-dimensional (2D) materials have been obtained by exfoliation of van der Waals crystals. Recently, there has been growing interest in fabricating synthetic 2D crystals which have no layered bulk analogues. These efforts have been focused mainly on the surface growth of molecules in high vacuum. Here, we report an approach to making 2D crystals of covalent solids by chemical conversion of van der Waals layers. As an example, we used 2D indium selenide (InSe) obtained by exfoliation and converted it by direct fluorination into indium fluoride (InF3), which has a nonlayered, rhombohedral structure and therefore cannot possibly be obtained by exfoliation. The conversion of InSe into InF3 is found to be feasible for thicknesses down to three layers of InSe, and the obtained stable InF3 layers are doped with selenium. We study this new 2D material by optical, electron transport, and Raman measurements and show that it is a semiconductor with a direct bandgap of 2.2 eV, exhibiting high optical transparency across the visible and infrared spectral ranges. We also demonstrate the scalability of our approach by chemical conversion of large-area, thin InSe laminates obtained by liquid exfoliation, into InF3 films. The concept of chemical conversion of cleavable thin van der Waals crystals into covalently bonded noncleavable ones opens exciting prospects for synthesizing a wide variety of novel atomically thin covalent crystals.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 12.712
Times cited: 32
DOI: 10.1021/ACS.NANOLETT.9B02700
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“Organic surface coating on Coccolithophores –, Emiliania huxleyi: its determination and implication in the marine carbon cycle”. Godoi RHM, Aerts K, Harlay J, Kaegi R, Ro C-U, Chou L, Van Grieken R, Microchemical journal 91, 266 (2009). http://doi.org/10.1016/J.MICROC.2008.12.009
Abstract: Most of the marine precipitation of CaCO3 is due to the biological activities of planktonic and benthic organisms in waters largely oversaturated with respect to calcium carbonates. This saturation state is expected to decrease as CO2 increases in seawater. A conventional view in oceanography suggests that calcium carbonates organisms are preserved in oversaturated waters and dissolve only below the lysocline. However, it has be postulated that a fraction of the CaCO3 precipitated biogenically could dissolve in oversaturated waters due to the formation of microenvironments in which respired CO2 decreases the saturation state of seawater (Ù) in the vicinity of CaCO3 crystals. In the present study, cells of the coccolithophore Emiliania huxleyi obtained from laboratory cultures and field samples collected in the Gulf of Biscay, were examined using variable-energy electron-probe microanalysis, to determine the presence and thickness of their organic coating. In addition, a new approach for transferring micrometer-sized particles from a filter onto transmission electron microscope grids using manipulators was used to investigate individual coccolithophores. The dry thickness of an organic coating over the coccolithophore surface was found to range between 280 and 350 nm. The resemblance of this coating to the carbohydrates produced and released by the cell is discussed as well as their potential for constituting a microenvironment that hosts bacteria. The properties of this organic coating and its role in the preservation/dissolution and export of biogenic carbonates in the water column are one of the major issues of carbonate geochemistry.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/J.MICROC.2008.12.009
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“How do western European farms behave and respond to climate change? A simultaneous irrigation-crop decision model”. Vanschoenwinkel J, Vancauteren M, Van Passel S, Climate change economics 13, 2250009 (2022). http://doi.org/10.1142/S2010007822500099
Abstract: Most farm adaptations are reactive actions that run the risk of locking farm systems into suboptimal long-term trajectories. This is especially the case with regard to water management as water scarcity will be aggravated by climate change. This paper looks into farm irrigation choices in combination with crop choices because a proper crop choice has the potential to reduce water requirements. It proposes an extended Ricardian model to capture multiple adaptation decisions explicitly. The new simultaneous irrigation-crop farm decision model uses spatially detailed farm-level data of over 18,000 European farms on irrigation and seven different crop choices. The analysis shows that larger farmers and farmers in less water-scarce regions that use irrigation are more sensitive to temperature increases than rain-fed agriculture. This might be explained by the fact that these farmers do not experience the real cost of water scarcity because of which they take less efficient decisions.
Keywords: A1 Journal article; Economics; Engineering Management (ENM)
DOI: 10.1142/S2010007822500099
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“Automated matrix-correction of line ratios in energy-dispersive x-ray fluorescence spectrum deconvolution”. Van Dyck P, Van Grieken R, X-ray spectrometry 12, 111 (1983). http://doi.org/10.1002/XRS.1300120306
Abstract: Most computer XRF-spectrum deconvolution routines make use of fixed intensity ratios for the lines from one element. The magnitude of the error that fixed ratios imply has been quantitatively evaluated for samples with a varible thickness or matrix. A procedure for routinely adapting the line ratios according to the matrix effect in every sample (by making use of the matrix information present in the scatter peaks) enhances the accuracy of the spectrum evaluation.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1002/XRS.1300120306
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“Quantitative 3D Investigation of Nanoparticle Assemblies by Volumetric Segmentation of Electron Tomography Data Sets”. Kavak S, Kadu AA, Claes N, Sánchez-Iglesias A, Liz-Marzán LM, Batenburg KJ, Bals S, The journal of physical chemistry: C : nanomaterials and interfaces 127, 9725 (2023). http://doi.org/10.1021/acs.jpcc.3c02017
Abstract: Morphological characterization of nanoparticle assemblies and hybrid nanomaterials is critical in determining their structure-property relationships as well as in the development of structures with desired properties. Electron tomography has become a widely utilized technique for the three-dimensional characterization of nanoparticle assemblies. However, the extraction of quantitative morphological parameters from the reconstructed volume can be a complex and labor-intensive task. In this study, we aim to overcome this challenge by automating the volumetric segmentation process applied to three-dimensional reconstructions of nanoparticle assemblies. The key to enabling automated characterization is to assess the performance of different volumetric segmentation methods in accurately extracting predefined quantitative descriptors for morphological characterization. In our methodology, we compare the quantitative descriptors obtained through manual segmentation with those obtained through automated segmentation methods, to evaluate their accuracy and effectiveness. To show generality, our study focuses on the characterization of assemblies of CdSe/CdS quantum dots, gold nanospheres and CdSe/CdS encapsulated in polymeric micelles, and silica-coated gold nanorods decorated with both CdSe/CdS or PbS quantum dots. We use two unsupervised segmentation algorithms: the watershed transform and the spherical Hough transform. Our results demonstrate that the choice of automated segmentation method is crucial for accurately extracting the predefined quantitative descriptors. Specifically, the spherical Hough transform exhibits superior performance in accurately extracting quantitative descriptors, such as particle size and interparticle distance, thereby allowing for an objective, efficient, and reliable volumetric segmentation of complex nanoparticle assemblies.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.7
Times cited: 2
DOI: 10.1021/acs.jpcc.3c02017
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“Evaluation of an electrochemical sensor and comparison with spectroscopic approaches as used today in practice for harm reduction in a festival setting: a case study : analysis of 3,4-methylenedioxymethamphetamine samples”. Deconinck E, Polet MA, Canfyn M, Duchateau C, De Braekeleer K, Van Echelpoel R, De Wael K, Gremeaux L, Degreef M, Balcaen M, Drug testing and analysis , 1 (2023). http://doi.org/10.1002/DTA.3625
Abstract: More and more countries and organisations emphasise the value of harm reduction measures in the context of illicit drug use and abuse. One of these measures is drug checking, a preventive action that can represent a quick win by tailored consultation on the risks of substance use upon analytical screening of a submitted sample. Unlike drop-in centres that operate within a fixed setting, enabling drug checking in a harm reduction context at events requires portable, easy to use analytical approaches, operated by personnel with limited knowledge of analytical chemistry. In this case study, four different approaches were compared for the characterisation of 3,4-methylenedioxymethamphetamine samples and this in the way the approaches would be applied today in an event context. The four approaches are mid-infrared (MIR), near-infrared, and Raman spectroscopy, which are today used in drug checking context in Belgium, as well as an electrochemical sensor approach initially developed in the context of law enforcement at ports. The MIR and the electrochemical approach came out best, with the latter allowing for a direct straightforward analysis of the percentage 3,4-methylenedioxymethamphetamine (as base equivalent) in the samples. However, MIR has the advantage that, in a broader drug checking context, it allows to screen for several molecules and so is able to identify unexpected active components or at least the group to which such components belong. The latter is also an important advantage in the context of the growing emergence of new psychotropic substances. MIR, NIR, Raman spectroscopy, and an electrochemical sensor (Narcoreader (R)) for MDMA analysis were compared in a realistic harm reduction context. NIR and Raman failed in simple library approaches. MIR and Narcoreader (R) were preferred. MIR came out as first choice. MIR and Narcoreader (R) have complementary (dis)advantages and could be used in a two-step approach: MIR for screening and Narcoreader (R) for dosage/risk evaluation of MDMA samples.image
Keywords: A1 Journal article; Pharmacology. Therapy; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
Impact Factor: 2.9
DOI: 10.1002/DTA.3625
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