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“Surface modification of titanium carbide MXene monolayers (Ti₂C and Ti₃C₂) via chalcogenide and halogenide atoms”. Faraji M, Bafekry A, Fadlallah MM, Molaei F, Hieu NN, Qian P, Ghergherehchi M, Gogova D, Physical Chemistry Chemical Physics 23, 15319 (2021). http://doi.org/10.1039/D1CP01788H
Abstract: Inspired by the recent successful growth of Ti2C and Ti3C2 monolayers, here, we investigate the structural, electronic, and mechanical properties of functionalized Ti2C and Ti3C2 monolayers by means of density functional theory calculations. The results reveal that monolayers of Ti2C and Ti3C2 are dynamically stable metals. Phonon band dispersion calculations demonstrate that two-surface functionalization of Ti2C and Ti(3)C(2)via chalcogenides (S, Se, and Te), halides (F, Cl, Br, and I), and oxygen atoms results in dynamically stable novel functionalized monolayer materials. Electronic band dispersions and density of states calculations reveal that all functionalized monolayer structures preserve the metallic nature of both Ti2C and Ti3C2 except Ti2C-O-2, which possesses the behavior of an indirect semiconductor via full-surface oxygen passivation. In addition, it is shown that although halide passivated Ti3C2 structures are still metallic, there exist multiple Dirac-like cones around the Fermi energy level, which indicates that semi-metallic behavior can be obtained upon external effects by tuning the energy of the Dirac cones. In addition, the computed linear-elastic parameters prove that functionalization is a powerful tool in tuning the mechanical properties of stiff monolayers of bare Ti2C and Ti3C2. Our study discloses that the electronic and structural properties of Ti2C and Ti3C2 MXene monolayers are suitable for surface modification, which is highly desirable for material property engineering and device integration.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 4.123
DOI: 10.1039/D1CP01788H
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“Tailoring dirac plasmons via anisotropic dielectric environment by design”. Tao ZH, Dong HM, Milošević, MV, Peeters FM, Van Duppen B, Physical Review Applied 16, 054030 (2021). http://doi.org/10.1103/PHYSREVAPPLIED.16.054030
Abstract: Dirac plasmons in a two-dimensional (2D) crystal are strongly affected by the dielectric properties of the environment, due to interaction of their electric field lines with the surrounding medium. Using graphene as a 2D reservoir of free carriers, one can engineer a material configuration that provides an anisotropic environment to the plasmons. In this work, we discuss the physical properties of Dirac plasmons in graphene surrounded by an arbitrary anisotropic dielectric and exemplify how h-BN-based heterostructures can be designed to bear the required anisotropic characteristics. We calculate how dielec-tric anisotropy impacts the spatial propagation of the plasmons and find that an anisotropy-induced plasmon mode emerges, together with a damping pathway, that stem from the out-of-plane off-diagonal elements in the dielectric tensor. Furthermore, we find that one can create hyperbolic plasmons by inher-iting the dielectric hyperbolicity of the designed material environment. Strong control over plasmon propagation patterns can be realized in a similar manner. Finally, we show that in this way one can also control the polarization of the light-matter excitations that constitute the plasmon. Taken together, our results promote the design of the dielectric environment as an effective path to tailor the plasmonic response of graphene on the nanoscopic level.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 4.808
Times cited: 2
DOI: 10.1103/PHYSREVAPPLIED.16.054030
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“Terahertz magneto-optical properties of graphene hydrodynamic electron liquid”. Man LF, Xu W, Xiao YM, Wen H, Ding L, Van Duppen B, Peeters FM, Physical Review B 104, 125420 (2021). http://doi.org/10.1103/PHYSREVB.104.125420
Abstract: The discovery of the hydrodynamic electron liquid (HEL) in graphene [D. Bandurin et al., Science 351, 1055 (2016) and J. Crossno et al., Science 351, 1058 (2016)] has marked the birth of the solid-state HEL which can be probed near room temperature in a table-top setup. Here we examine the terahertz (THz) magneto-optical (MO) properties of a graphene HEL. Considering the case where the magnetic length l(B) = root h/eB is comparable to the mean-free path l(ee) for electron-electron interaction in graphene, the MO conductivities are obtained by taking a momentum balance equation approach on the basis of the Boltzmann equation. We find that when l(B) similar to l(ee), the viscous effect in a HEL can weaken significantly the THz MO effects such as cyclotron resonance and Faraday rotation. The upper hybrid and cyclotron resonance magnetoplasmon modes omega(+/-) are also obtained through the RPA dielectric function. The magnetoplasmons of graphene HEL at large wave-vector regime are affected by the viscous effect, and results in red-shifts of the magnetoplasmon frequencies. We predict that the viscosity in graphene HEL can affect strongly the magneto-optical and magnetoplasmonic properties, which can be verified experimentally.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 4
DOI: 10.1103/PHYSREVB.104.125420
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“Theoretical prediction of the PtOX (X = S and Se) monolayers as promising optoelectronic and thermoelectric 2D materials”. Nguyen DK, Hoat DM, Bafekry A, Van On V, Rivas-Silva JF, Naseri M, Cocoletzi GH, Physica E-Low-Dimensional Systems &, Nanostructures 131, 114732 (2021). http://doi.org/10.1016/J.PHYSE.2021.114732
Abstract: In this paper, two new monolayers, namely PtOS and PtOSe, are theoretically predicted using first-principles calculations. Structural, electronic, optical and thermoelectric properties are explored using full-potential linearized augmented plane-wave (FP-LAPW) method and the semiclassical Boltzmann transport theory. Predicted two-dimensional (2D) materials show good dynamical, thermodynamic and structural stability. Calculated electronic structures indicate the indirect gap semiconductor nature of the PtOS and PtOSe single layers with energy gap of 1.346(2.436) and 0.978(1.978) eV as calculated with the WC(HSE06) functional, respectively. Density of states spectra and valence charge distribution maps suggest a mix of covalent and ionic characters of the chemical bonds. 2D materials at hand exhibit good absorption property in the visible regime with coefficient value reaching the order of 105/cm, even much larger in the ultraviolet, suggesting the promising optoelectronic applicability. Finally, the thermoelectric parameters including electrical conductivity, thermal conductivity, Seebeck coefficient, power factor and figure of merit are determined and analyzed. Results indicate prospective thermoelectric performance of both considered single layers as demonstrated by large figure of merit close to unity. Our work introduces two new 2D multifunctional materials that may possess potential applications in the optoelectronic and thermoelectric nano-devices.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 2.221
DOI: 10.1016/J.PHYSE.2021.114732
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“Thermodynamic equilibrium theory revealing increased hysteresis in ferroelectric field-effect transistors with free charge accumulation”. Bizindavyi J, Verhulst AS, Sorée B, Vandenberghe WG, Communications Physics 4, 86 (2021). http://doi.org/10.1038/S42005-021-00583-7
Abstract: At the core of the theoretical framework of the ferroelectric field-effect transistor (FeFET) is the thermodynamic principle that one can determine the equilibrium behavior of ferroelectric (FERRO) systems using the appropriate thermodynamic potential. In literature, it is often implicitly assumed, without formal justification, that the Gibbs free energy is the appropriate potential and that the impact of free charge accumulation can be neglected. In this Article, we first formally demonstrate that the Grand Potential is the appropriate thermodynamic potential to analyze the equilibrium behavior of perfectly coherent and uniform FERRO-systems. We demonstrate that the Grand Potential only reduces to the Gibbs free energy for perfectly non-conductive FERRO-systems. Consequently, the Grand Potential is always required for free charge-conducting FERRO-systems. We demonstrate that free charge accumulation at the FERRO interface increases the hysteretic device characteristics. Lastly, a theoretical best-case upper limit for the interface defect density D-FI is identified. The ferroelectric field-effect transistor, which has attracted much attention for application as both a highly energy-efficient logic device and a non-volatile memory device, has often been studied within the framework of equilibrium thermodynamics. Here, the authors theoretically demonstrate the importance of utilizing the correct thermodynamic potential and investigate the impact of free charge accumulation on the equilibrium performance of ferroelectric-based systems.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
DOI: 10.1038/S42005-021-00583-7
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“TMDlib2 and TMDplotter : a platform for 3D hadron structure studies”. Abdulov NA, Bacchetta A, Baranov S, Martinez AB, Bertone V, Bissolotti C, Candelise V, Banos LIE, Bury M, Connor PLS, Favart L, Guzman F, Hautmann F, Hentschinski M, Jung H, Keersmaekers L, Kotikov A, Kusina A, Kutak K, Lelek A, Lidrych J, Lipatov A, Lykasov G, Malyshev M, Mendizabal M, Prestel S, Barzani SS, Sapeta S, Schmitz M, Signori A, Sorrentino G, Monfared ST, van Hameren A, van Kampen AM, Vanden Bemden M, Vladimirov A, Wang Q, Yang H, European Physical Journal C 81, 752 (2021). http://doi.org/10.1140/EPJC/S10052-021-09508-8
Abstract: A common library, TMDlib2, for Transverse-Momentum-Dependent distributions (TMDs) and unintegrated parton distributions (uPDFs) is described, which allows for easy access of commonly used TMDs and uPDFs, providing a three-dimensional (3D) picture of the partonic structure of hadrons. The tool TMDplotter allows for web-based plotting of distributions implemented in TMDlib2, together with collinear pdfs as available in LHAPDF.
Keywords: A1 Journal article; Particle Physics Group; Condensed Matter Theory (CMT)
Impact Factor: 5.331
DOI: 10.1140/EPJC/S10052-021-09508-8
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“Topological phase transitions and Majorana zero modes in DNA double helix coupled to s-wave superconductors”. Chen Q, Guo A-M, Liu J, Peeters FM, Sun Q-F, New Journal Of Physics 23, 093047 (2021). http://doi.org/10.1088/1367-2630/AC2711
Abstract: Topological properties of a double-stranded DNA (dsDNA) proximity-coupled by an s-wave superconductor are investigated, in which the energy spectra and the differential conductance are calculated within the framework of tight-binding approximation. Our results indicate that this dsDNA-superconductor system hosts Majorana zero modes (MZMs) when the Zeeman field is perpendicular to the helix axis, whereas no MZM could be observed when the Zeeman field is parallel to the helix axis, in sharp contrast to previous studies on nanowires including single-stranded DNA. In particular, two topological phase transitions could take place in the dsDNA-superconductor system by changing the Zeeman field, one from a topological trivial phase to a topological nontrivial phase with one pair of MZMs in small Zeeman field regime, and the other from a phase with one pair of MZMs to a phase with two pairs of MZMs by further increasing the Zeeman field. In the presence of a gate field normal to the helix axis, the topological nontrivial phase with two pairs of MZMs can transform into the phase with one pair of MZMs. The topological phase with one pair of MZMs is more stable and robust against Anderson disorder.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.786
Times cited: 7
DOI: 10.1088/1367-2630/AC2711
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“Torque field and skyrmion motion by spin transfer torque in a quasi-2D interface in presence of strong spin-orbit interaction”. Osca J, Sorée B, Journal Of Applied Physics 130, 133903 (2021). http://doi.org/10.1063/5.0063887
Abstract: We investigate the torque field and skyrmion motion at an interface between a ferromagnet hosting a skyrmion and a material with a strong spin-orbit interaction. We analyze both semiconductor materials and topological insulators using a Hamiltonian model that includes a linear term. The spin torque-inducing current is considered to flow in the single band limit; therefore, a quantum model of current is used. Skyrmion motion due to spin transfer torque proves to be more difficult in the presence of a spin-orbit interaction in the case where only interface in-plane currents are present. However, edge effects in narrow nanowires can be used to drive the skyrmion motion and to exert a limited control on its motion direction. We also show the differences and similarities between torque fields due to electric current in the many and single band limits. Published under an exclusive license by AIP Publishing.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.068
DOI: 10.1063/5.0063887
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“Towards modelling active sound localisation based on Bayesian inference in a static environment”. McLachlan G, Majdak P, Reijniers J, Peremans H, Acta Acustica 5, 45 (2021). http://doi.org/10.1051/AACUS/2021039
Abstract: Over the decades, Bayesian statistical inference has become a staple technique for modelling human multisensory perception. Many studies have successfully shown how sensory and prior information can be combined to optimally interpret our environment. Because of the multiple sound localisation cues available in the binaural signal, sound localisation models based on Bayesian inference are a promising way of explaining behavioural human data. An interesting aspect is the consideration of dynamic localisation cues obtained through self-motion. Here we provide a review of the recent developments in modelling dynamic sound localisation with a particular focus on Bayesian inference. Further, we describe a theoretical Bayesian framework capable to model dynamic and active listening situations in humans in a static auditory environment. In order to demonstrate its potential in future implementations, we provide results from two examples of simplified versions of that framework.
Keywords: A1 Journal article; Engineering Management (ENM); Condensed Matter Theory (CMT)
DOI: 10.1051/AACUS/2021039
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“Tunable coupling of terahertz Dirac plasmons and phonons in transition metal dichalcogenide-based van der Waals heterostructures”. Lavor IR, Chaves A, Peeters FM, Van Duppen B, 2d Materials , 015018 (2021). http://doi.org/10.1088/2053-1583/AC37A8
Abstract: Dirac plasmons in graphene hybridize with phonons of transition metal dichalcogenides (TMDs) when the materials are combined in so-called van der Waals heterostructures (vdWh), thus forming surface plasmon-phonon polaritons (SPPPs). The extend to which these modes are coupled depends on the TMD composition and structure, but also on the plasmons' properties. By performing realistic simulations that account for the contribution of each layer of the vdWh separately, we calculate how the strength of plasmon-phonon coupling depends on the number and composition of TMD layers, on the graphene Fermi energy and the specific phonon mode. From this, we present a semiclassical theory that is capable of capturing all relevant characteristics of the SPPPs. We find that it is possible to realize both strong and ultra-strong coupling regimes by tuning graphene's Fermi energy and changing TMD layer number.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 6.937
Times cited: 1
DOI: 10.1088/2053-1583/AC37A8
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“Tunable effective masses of magneto-excitons in two-dimensional materials”. Chaves A, Peeters FM, Solid State Communications 334, 114371 (2021). http://doi.org/10.1016/J.SSC.2021.114371
Abstract: Excitonic properties of Ge2H2 and Sn2H2, also known as Xanes, are investigated within the effective mass model. A perpendicularly applied magnetic field induces a negative shift on the exciton center-of-mass kinetic energy that is approximately quadratic with its momentum, thus pushing down the exciton dispersion curve and flattening it. This can be interpreted as an increase in the effective mass of the magneto-exciton, tunable by the field intensity. Our results show that in low effective mass two-dimensional semiconductors, such as Xanes, the applied magnetic field allows one to tune the magneto-exciton effective mass over a wide range of values.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.554
DOI: 10.1016/J.SSC.2021.114371
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“Tunable electronic and magnetic properties of MoSi₂N₄, monolayer via vacancy defects, atomic adsorption and atomic doping”. Bafekry A, Faraji M, Fadlallah MM, Khatibani AB, Ziabari A abdolahzadeh, Ghergherehchi M, Nedaei S, Shayesteh SF, Gogova D, Applied Surface Science 559, 149862 (2021). http://doi.org/10.1016/J.APSUSC.2021.149862
Abstract: The two dimensional MoSi2N4 (MSN) monolayer exhibiting rich physical and chemical properties was synthesized for the first time last year. We have used the spin-polarized density functional theory to study the effect of different types of point defects on the structural, electronic, and magnetic properties of the MSN monolayer. Adsorbed, substitutionally doped (at different lattice sites), and some kind of vacancies have been considered as point defects. The computational results show all defects studied decrease the MSN monolayer band gap. We found out the H-, O-, and P-doped MSN are n-type conductors. The arsenic-doped MSN, and MSN with vacancy defects have a magnetic moment. The MSN with a Si vacancy defect is a half-metallic which is favorable for spintronic applications, while the MSN with a single N vacancy or double vacancy (N + S) defects are metallic, i. e., beneficial as spin filters and chemical sensors.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.387
DOI: 10.1016/J.APSUSC.2021.149862
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“Tunable natural terahertz and mid-infrared hyperbolic plasmons in carbon phosphide”. Dehdast M, Valiollahi Z, Neek-Amal M, Van Duppen B, Peeters FM, Pourfath M, Carbon 178, 625 (2021). http://doi.org/10.1016/J.CARBON.2021.03.040
Abstract: Hyperbolic polaritons in ultra thin materials such as few layers of van derWaals heterostructures provide a unique control over light-matter interaction at the nanoscale and with various applications in flat optics. Natural hyperbolic surface plasmons have been observed on thin films of WTe2 in the light wavelength range of 16-23 mu m (similar or equal to 13-18 THz) [Nat. Commun. 11, 1158 (2020)]. Using time-dependent density functional theory, it is found that carbon doped monolayer phosphorene (beta-allotrope of carbon phosphide monolayer) exhibits natural hyperbolic plasmons at frequencies above similar or equal to 5 THz which is not observed in its parent materials, i.e. monolayer of black phosphorous and graphene. Furthermore, we found that by electrostatic doping the plasmonic frequency range can be extended to the mid-infrared. (C) 2021 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 6.337
Times cited: 11
DOI: 10.1016/J.CARBON.2021.03.040
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Gonzalez Garcia A (2021) Tuning the properties of group III-As in the thinnest limit : a theoretical study of single layer and 2D-heterostructures. xvii, 175 p
Abstract: In this thesis, a first-principles research to tune the physical properties of group III-V materials in the thinnest limit is carried out. Among the different methods to tune the mechanical, electronic and magnetic properties of these graphene related materials, we use: two-dimensional (2D) multilayers, straintronics, hydrogen functionalization, and transition metal adsorption. The first part of this research is devoted to a complete characterization of the structural, electronic, mechanical and vibrational properties of 2D group III-As monolayers, obtained from density functional theory. Our findings are used to understand the contribution of the
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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“Two-dimensional buckled tetragonal cadmium chalcogenides including CdS, CdSe, and CdTe monolayers as photo-catalysts for water splitting”. Naseri M, Bafekry A, Faraji M, Hoat DM, Fadlallah MM, Ghergherehchi M, Sabbaghi N, Gogova D, Physical Chemistry Chemical Physics 23, 12226 (2021). http://doi.org/10.1039/D1CP00317H
Abstract: Pure hydrogen production via water splitting is an ideal strategy for producing clean and sustainable energy. Two-dimensional (2D) cadmium chalcogenide single-layers with a tetragonal crystal structure, namely Tetra-CdX (X = S, Se, and Te) monolayers, are theoretically predicted by means of density functional theory (DFT). Their structural stability and electronic and optical properties are investigated. We find that Tetra-CdX single-layers are thermodynamically stable. Their stability decreases as we go down the 6A group in the periodic table, i.e., from X = S to Se, and Te which also means that the electronegativity decreases. All considered novel monolayers are indirect band gap semiconductors. Using the HSE06 functional the electronic band gaps of CdS, CdSe, and CdTe monolayers are predicted to be 3.10 eV, 2.97 eV, and 2.90 eV, respectively. The impact of mechanical strain on the physical properties was studied, which indicates that compressive strain increases the band gap and tensile strain decreases the band gap. The optical properties of the Tetra-CdX monolayers show the ability of these monolayers to absorb visible light. Due to the suitable band gaps and band edge positions of Tetra-CdX, these newly discovered 2D materials are promising for photocatalytic water splitting.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 4.123
DOI: 10.1039/D1CP00317H
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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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“Ultra-thin structures of manganese fluorides : conversion from manganese dichalcogenides by fluorination”. Baskurt M, Nair RR, Peeters FM, Sahin H, Physical Chemistry Chemical Physics 23, 10218 (2021). http://doi.org/10.1039/D1CP00293G
Abstract: In this study, it is predicted by density functional theory calculations that graphene-like novel ultra-thin phases of manganese fluoride crystals, that have nonlayered structures in their bulk form, can be stabilized by fluorination of manganese dichalcogenide crystals. First, it is shown that substitution of fluorine atoms with chalcogens in the manganese dichalcogenide host lattice is favorable. Among possible crystal formations, three stable ultra-thin structures of manganese fluoride, 1H-MnF2, 1T-MnF2 and MnF3, are found to be stable by total energy optimization calculations. In addition, phonon calculations and Raman activity analysis reveal that predicted novel single-layers are dynamically stable crystal structures displaying distinctive characteristic peaks in their vibrational spectrum enabling experimental determination of the corresponding phases. Differing from 1H-MnF2 antiferromagnetic (AFM) large gap semiconductor, 1T-MnF2 and MnF3 single-layers are semiconductors with ferromagnetic (FM) ground state.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 4.123
Times cited: 1
DOI: 10.1039/D1CP00293G
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“Vibrational and optical identification of GeO₂, and GeO single layers : a first-principles study”. Sozen Y, Yagmurcukardes M, Sahin H, Physical Chemistry Chemical Physics 23, 21307 (2021). http://doi.org/10.1039/D1CP02299G
Abstract: In the present work, the identification of two hexagonal phases of germanium oxides (namely GeO2 and GeO) through the vibrational and optical properties is reported using density functional theory calculations. While structural optimizations show that single-layer GeO2 and GeO crystallize in 1T and buckled phases, phonon band dispersions reveal the dynamical stability of each structure. First-order off-resonant Raman spectral predictions demonstrate that each free-standing single-layer possesses characteristic peaks that are representative for the identification of the germanium oxide phase. On the other hand, electronic band dispersion analysis shows the insulating and large-gap semiconducting nature of single-layer GeO2 and GeO, respectively. Moreover, optical absorption, reflectance, and transmittance spectra obtained by means of G(0)W(0)-BSE calculations reveal the existence of tightly bound excitons in each phase, displaying strong optical absorption. Furthermore, the excitonic gaps are found to be at deep UV and visible portions of the spectrum, for GeO2 and GeO crystals, with energies of 6.24 and 3.10 eV, respectively. In addition, at the prominent excitonic resonances, single-layers display high reflectivity with a zero transmittance, which is another indication of the strong light-matter interaction inside the crystal medium.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 4.123
DOI: 10.1039/D1CP02299G
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“Vibrational properties and thermal transport in quaternary chalcogenides : the case of Te-based compositions”. Shi W, Pandey T, Lindsay L, Woods LM, Physical review materials 5, 045401 (2021). http://doi.org/10.1103/PHYSREVMATERIALS.5.045401
Abstract: Vibrational thermal properties of CuZn2InTe4, AgZn2InTe4, and Cu2CdSnTe4, derived from binary II-VI zinc-blendes, are reported based on first-principles calculations. While the chalcogenide atoms in these materials have the same lattice positions, the cation atom arrangements vary, resulting in different crystal symmetries and subsequent properties. The compositional differences have important effects on the vibrational thermal characteristics of the studied materials, which demonstrate that low-frequency optical phonons hybridize with acoustic phonons and lead to enhanced phonon-phonon scattering and low lattice thermal conductivities. The phonon density of states, mode Gruneisen parameters, and phonon scattering rates are also calculated, enabling deeper insight into the microscopic thermal conduction processes in these materials. Compositional variations drive differences among the three materials considered here; nonetheless, their structural similarities and generally low thermal conductivities (0.5-4 W/mK at room temperature) suggest that other similar II-VI zinc-blende derived materials will also exhibit similarly low values, as also corroborated by experimental data. This, combined with the versatility in designing a variety of motifs on the overall structure, makes quaternary chalcogenides interesting for thermal management and energy conversion applications that require low thermal conductivity.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
DOI: 10.1103/PHYSREVMATERIALS.5.045401
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“Early stages of dissolution corrosion in 316L and DIN 1.4970 austenitic stainless steels with and without anticorrosion coatings in static liquid lead-bismuth eutectic (LBE) at 500 degrees C”. Charalampopoulou E, Lambrinou K, Van der Donck T, Paladino B, Di Fonzo F, Azina C, Eklund P, Mraz S, Schneider JM, Schryvers D, Delville R, Materials Characterization 178, 111234 (2021). http://doi.org/10.1016/J.MATCHAR.2021.111234
Abstract: This work addresses the early stages (<= 1000 h) of the dissolution corrosion behavior of 316L and DIN 1.4970 austenitic stainless steels in contact with oxygen-poor (C-O < 10(-8) mass%), static liquid lead-bismuth eutectic (LBE) at 500 degrees C for 600-1000 h. The objective of this study was to determine the relative early-stage resistance of the uncoated steels to dissolution corrosion and to assess the protectiveness of select candidate coatings (Cr2AlC, Al2O3, V2AlxCy). The simultaneous exposure of steels with intended differences in microstructure and thermomechanical state showed the effects of steel grain size, density of annealing/deformation twins, and secondary precipitates on the steel dissolution corrosion behavior. The findings of this study provide recommendations on steel manufacturing with the aim of using the steels to construct Gen-IV lead-cooled fast reactors.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 2.714
DOI: 10.1016/J.MATCHAR.2021.111234
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“Determination of spinel content in cycled Li1.2Ni0.13Mn0.54Co0.13O2 using three-dimensional electron diffraction and precession electron diffraction”. Quintelier M, Perkisas T, Poppe R, Batuk M, Hendrickx M, Hadermann J, Symmetry-Basel 13, 1989 (2021). http://doi.org/10.3390/SYM13111989
Abstract: Among lithium battery cathode materials, Li1.2Ni0.13Mn0.54Co0.13O2 (LR-NMC) has a high theoretical capacity, but suffers from voltage and capacity fade during cycling. This is partially ascribed to transition metal cation migration, which involves the local transformation of the honeycomb layered structure to spinel-like nano-domains. Determination of the honeycomb layered/spinel phase ratio from powder X-ray diffraction data is hindered by the nanoscale of the functional material and the domains, diverse types of twinning, stacking faults, and the possible presence of the rock salt phase. Determining the phase ratio from transmission electron microscopy imaging can only be done for thin regions near the surfaces of the crystals, and the intense beam that is needed for imaging induces the same transformation to spinel as cycling does. In this article, it is demonstrated that the low electron dose sufficient for electron diffraction allows the collection of data without inducing a phase transformation. Using calculated electron diffraction patterns, we demonstrate that it is possible to determine the volume ratio of the different phases in the particles using a pair-wise comparison of the intensities of the reflections. Using this method, the volume ratio of spinel structure to honeycomb layered structure is determined for a submicron sized crystal from experimental three-dimensional electron diffraction (3D ED) and precession electron diffraction (PED) data. Both twinning and the possible presence of the rock salt phase are taken into account. After 150 charge-discharge cycles, 4% of the volume in LR-NMC particles was transformed irreversibly from the honeycomb layered structure to the spinel structure. The proposed method would be applicable to other multi-phase materials as well.
Keywords: A1 Journal article; Engineering sciences. Technology; Engineering Management (ENM); Electron microscopy for materials research (EMAT)
Impact Factor: 1.457
DOI: 10.3390/SYM13111989
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“Phase retrieval from 4-dimensional electron diffraction datasets”. Friedrich T, Yu C-P, Verbeek J, Pennycook T, Van Aert S, Proceedings
T2 –, IEEE International Conference on Image Processing (ICIP), SEP 19-22, 2021, Electr. network , 3453 (2021). http://doi.org/10.1109/ICIP42928.2021.9506709
Abstract: We present a computational imaging mode for large scale electron microscopy data, which retrieves a complex wave from noisy/sparse intensity recordings using a deep learning approach and subsequently reconstructs an image of the specimen from the Convolutional Neural Network (CNN) predicted exit waves. We demonstrate that an appropriate forward model in combination with open data frameworks can be used to generate large synthetic datasets for training. In combination with augmenting the data with Poisson noise corresponding to varying dose-values, we effectively eliminate overfitting issues. The U-NET[1] based architecture of the CNN is adapted to the task at hand and performs well while maintaining a relatively small size and fast performance. The validity of the approach is confirmed by comparing the reconstruction to well-established methods using simulated, as well as real electron microscopy data. The proposed method is shown to be effective particularly in the low dose range, evident by strong suppression of noise, good spatial resolution, and sensitivity to different atom types, enabling the simultaneous visualisation of light and heavy elements and making different atomic species distinguishable. Since the method acts on a very local scale and is comparatively fast it bears the potential to be used for near-real-time reconstruction during data acquisition.
Keywords: P1 Proceeding; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
DOI: 10.1109/ICIP42928.2021.9506709
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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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“A database system for querying of river networks : facilitating monitoring and prediction applications”. Bollen E, Pagan BR, Kuijpers B, Van Hoey S, Desmet N, Hendrix R, Dams J, Seuntjens P, Water Science And Technology-Water Supply (2021). http://doi.org/10.2166/WS.2021.433
Abstract: The increasing availability of real-time in situ measurements and remote sensing observations have the potential to contribute to the optimization of water resources management. Global challenges such as climate change, intensive agriculture and urbanization put a high pressure on our water resources. Due to recent innovations in measuring both water quantity and quality, river systems can now be monitored in real time at an unprecedented spatial and temporal scale. To interpret the sensor measurements and remote sensing observations additional data for example on: the location of the measurement, upstream and downstream catchment characteristics, horizontal ellipsis are required. In this paper, we present a data management system to support flow-path related functionality for decision making and prediction modelling. Adding meta data sets and facilitating (near) real-time processing of sensor data questions are key concepts for the systems. The potential of the database framework for hydrological applications is demonstrated using different applications for the river system of Flanders. In one, the database framework is used to simulate the daily discharge for each segment within a catchment using a simple data-driven approach. The presented system is useful for numerous applications including pollution tracking, alerting and inter-sensor validation in river systems, or related networks.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 0.573
DOI: 10.2166/WS.2021.433
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“A new generalized empirical correlation for predicting methane hydrate equilibrium conditions in pure water”. Kummamuru NB, Perreault P, Lenaerts S, Industrial &, Engineering Chemistry Research 60, 3474 (2021). http://doi.org/10.1021/ACS.IECR.0C05833
Abstract: This work contributes to a new generalized empirical correlation for predicting methane (CH4) hydrate equilibrium conditions in pure water. Unlike the conventional thermodynamic approach that involves complex reckoning, the proposed empirical equation is developed by regressing 215 experimental data points from the literature and validating with 45 data points for predicting methane hydrate equilibrium conditions in pure water. The new correlation is proposed for a temperature and pressure range of 273.2–303.48 K and 2.63–72.26 MPa, respectively. The accuracy and performance of the proposed correlation is quantitatively evaluated using statistical error analysis. The proposed correlation was able to estimate CH4 hydrate equilibrium conditions satisfactorily with an R2 of 0.99987. The overall error analysis for the proposed correlation shows fair agreement with the experimental data reported within the literature. Concurrently, the new correlation showed better performance in predicting equilibrium conditions compared to those calculated by other empirical correlations available in the literature within the investigated range. In addition, the proposed empirical equation is also checked to evaluate its efficacy in fitting each set of experimental binary/ternary methane hydrates (BTMH) and binary hydrogen hydrates (BHH) for an accurate representation of equilibrium data over a wide range of composition, pressure, and temperature conditions. A maximum percentage deviation of 0.58% and 0.24% was observed between experimental and calculated equilibrium conditions for BTMH and BHH, respectively.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 2.843
DOI: 10.1021/ACS.IECR.0C05833
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“A review of technological solutions to prevent or reduce marine plastic litter in developing countries”. Winterstetter A, Grodent M, Kini V, Ragaert K, Vrancken KCM, Sustainability 13, 4894 (2021). http://doi.org/10.3390/SU13094894
Abstract: Growing global plastic production combined with poor waste collection has led to increasing amounts of plastic debris being found in oceans, rivers and on shores. The goal of this study is to provide an overview on currently available technological solutions to tackle marine plastic litter and to assess their potential use in developing countries. To compile an inventory of technological solutions, a dedicated online platform was developed. A total of 51 out of initially 75 submitted solutions along the plastics value chain were assessed by independent experts. Collection systems represent more than half of the shortlisted solutions. A quarter include processing and treatment technologies, either as a stand-alone solution (30%) or, more commonly, in combination with a first litter capturing step. Ten percent offer digital solutions. The rest focuses on integrated waste management solutions. For each stage in the source-to-sea spectrum-land, rivers, sea-two illustrative examples are described in detail. This study concludes that the most cost-effective type of solution tackles land-based sources of marine litter and combines technology with people-oriented practices, runs on own energy sources, connects throughout the plastics value chain with a convincing valorization plan for captured debris, and involves all relevant stakeholders.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 1.789
DOI: 10.3390/SU13094894
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“Ab initio modeling of few-layer dilute magnetic semiconductors”. Tiwari S, Van de Put ML, Sorée B, Vandenberghe WG, International Conference on Simulation of Semiconductor Processes and Devices : [proceedings]
T2 –, International Conference on Simulation of Semiconductor Processes and, Devices (SISPAD), SEP 27-29, 2021, Dallas, TX , 141 (2021). http://doi.org/10.1109/SISPAD54002.2021.9592535
Abstract: We present a computational model to model the magnetic structure of two-dimensional (2D) dilute-magnetic-semiconductors (DMS) both the monolayers and multilayers using first-principles density functional theory (DFT), as well as their magnetic phase transition as a function of temperature using Monte-Carlo simulations. Using our method, we model the magnetic structure of bulk, bilayer, and monolayer MoS2 substitutionally doped with Fe atoms. We find that the out-of-plane interaction in bilayer MoS2 is weakly ferromagnetic, whereas in bulk MoS2 it is strongly anti-ferromagnetic. Finally, we show that the magnetic order is more robust in bilayer Fe-doped MoS2 compared to the monolayer and results in a room-temperature FM at an atomic substitution of 14-16%.
Keywords: P1 Proceeding; Engineering sciences. Technology; Condensed Matter Theory (CMT)
DOI: 10.1109/SISPAD54002.2021.9592535
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“Accurate simulations of the reaction of H₂, on a curved Pt crystal through machine learning”. Gerrits N, Journal Of Physical Chemistry Letters 12, 12157 (2021). http://doi.org/10.1021/ACS.JPCLETT.1C03395
Abstract: Theoretical studies on molecule-metal surface reactions have so far been limited to small surface unit cells due to computational costs. Here, for the first time molecular dynamics simulations on very large surface unit cells at the level of density functional theory are performed, allowing a direct comparison to experiments performed on a curved crystal. Specifically, the reaction of D-2 on a curved Pt crystal is investigated with a neural network potential (NNP). The developed NNP is also accurate for surface unit cells considerably larger than those that have been included in the training data, allowing dynamical simulations on very large surface unit cells that otherwise would have been intractable. Important and complex aspects of the reaction mechanism are discovered such as diffusion and a shadow effect of the step. Furthermore, conclusions from simulations on smaller surface unit cells cannot always be transfered to larger surface unit cells, limiting the applicability of theoretical studies of smaller surface unit cells to heterogeneous catalysts with small defect densities.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 9.353
DOI: 10.1021/ACS.JPCLETT.1C03395
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“Acoustically driven stark effect in transition metal dichalcogenide monolayers”. Scolfaro D, Finamor M, Trinchao LO, Rosa BLT, Chaves A, Santos P V, Iikawa F, Couto ODD Jr, Acs Nano 15, 15371 (2021). http://doi.org/10.1021/ACSNANO.1C06854
Abstract: The Stark effect is one of the most efficient mechanisms to manipulate many-body states in nanostructured systems. In mono- and few-layer transition metal dichalcogenides, it has been successfully induced by optical and electric field means. Here, we tune the optical emission energies and dissociate excitonic states in MoSe2 monolayers employing the 220 MHz in-plane piezoelectric field carried by surface acoustic waves. We transfer the monolayers to high dielectric constant piezoelectric substrates, where the neutral exciton binding energy is reduced, allowing us to efficiently quench (above 90%) and red-shift the excitonic optical emissions. A model for the acoustically induced Stark effect yields neutral exciton and trion in-plane polarizabilities of 530 and 630 x 10(-5) meV/(kV/cm)(2), respectively, which are considerably larger than those reported for monolayers encapsulated in hexagonal boron nitride. Large in-plane polarizabilities are an attractive ingredient to manipulate and modulate multiexciton interactions in two-dimensional semiconductor nanostructures for optoelectronic applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 13.942
DOI: 10.1021/ACSNANO.1C06854
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Legrand S (2021) Advanced chemical imaging of artworks. 315 p
Abstract: Last century the field of heritage sciences expanded beyond imagination. The inventions of X-ray radiography and infrared reflectography allowed experts to investigate paintings below the surface as well. More recent developments led to the advent of the field of hyperspectral imaging, to which the advanced chemical imaging methods, used in this thesis work, belong. These techniques not only allow to identify the components present in artworks, but also to visualize their distribution over these objects. The resulting distribution maps permit a broader public to interpret the scientific data and to relate these results with the artwork itself. During this thesis work a range of flat artworks were investigated in a non-destructive manner using mainly two macroscopic imaging techniques: macroscopic X-ray fluorescence scanning and macroscopic Fourier transformed mid-infrared scanning in reflectance mode. The resulting images were sometimes supplemented with microscopic techniques on a minute selection of samples to fully understand the layer build-up, composition and distribution of these materials over the stratigraphy. Illuminated manuscripts pushed the interpretation of the macroscopic imaging techniques: due to the impossibility of sampling, all answers had to be obtained non-destructively. Documenting masterpieces such as the Ghent Altarpiece by means of chemical imaging techniques, helped the restoration team, assisted by the international commission to make the daring decision of manually removing the non-original paint layers. Scanning stained-glass windows allowed experts to document the panels, create situation reports, identify later infills and guide the restoration process in a more efficient manner. By initially applying non-destructive imaging techniques, many of the research/conservation questions could already be answered. Based on the resulting distribution maps, only a very limited amount of sampling was required to obtain a representative set to answer the remaining questions. In most cases the combination of multiple methods was necessary to fully understand the situation. A similar trend could be seen in the research field: the collaboration between divergent disciples was often required in order to explain all observations. In order to completely break through, the scanning speed of these techniques has to increase even more in order to cover an acceptable surface in one workday. Parallel with the operational speed, the (basic) data treatment should also be streamlined more in order to allow a broader user group to access the results. Once these two improvements are carried out, these techniques become accessible to a larger public.
Keywords: Doctoral thesis; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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