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“Unconventional dynamics of vortex shells in mesoscopic superconducting corbino disks”. Misko VR, Lin NS, Peeters FM, Physica: C : superconductivity 470, 939 (2010). http://doi.org/10.1016/j.physc.2010.02.058
Abstract: The dynamics of vortex matter in mesoscopic superconducting Corbino disk is strongly influenced by the discrete vortex structure arranged in shells. While in previous works the vortex dynamics has been studied in large (macroscopic) and in very small mesoscopic disks (containing only few shells), in the intermediate-size regime it is much more complex and unusual, due to: (i) the competition between the vortexvortex interaction and confinement and (ii) (in)commensurability among the vortex shells. We found that the interplay between these effects can result in a very unusual vortex dynamical behavior: (i) unconventional angular melting (i.e., propagating from the boundary, where the shear stress is minimum, towards the center) and (ii) unconventional dynamics of shells (i.e., the inversion of shell velocities with respect to the gradient driving force). This unusual behavior is found for different number of shells.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.404
Times cited: 3
DOI: 10.1016/j.physc.2010.02.058
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“Magnetic flux pinning in superconductors with hyperbolic-tesselation arrays of pinning sites”. Misko VR, Nori F, Physical review : B : condensed matter and materials physics 85, 184506 (2012). http://doi.org/10.1103/PhysRevB.85.184506
Abstract: We study magnetic flux interacting with arrays of pinning sites (APSs) placed on vertices of hyperbolic tesselations (HTs). We show that, due to the gradient in the density of pinning sites, HT APSs are capable of trapping vortices for a broad range of applied magnetic fluxes. Thus, the penetration of magnetic field in HT APSs is essentially different from the usual scenario predicted by the Bean model. We demonstrate that, due to the enhanced asymmetry of the surface barrier for vortex entry and exit, this HT APS could be used as a “capacitor” to store magnetic flux.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 24
DOI: 10.1103/PhysRevB.85.184506
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“Dynamics of vortex shells in mesoscopic superconducting Corbino disks”. Misko VR, Peeters FM, Physical review : B : condensed matter and materials physics 74, Artn 174507 (2006). http://doi.org/10.1103/PhysRevB.74.174507
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 30
DOI: 10.1103/PhysRevB.74.174507
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“Enhancement of the critical current in quasiperiodic pinning arrays : one-dimensional chains and Penrose lattices”. Misko VR, Savel'ev S, Nori F, Physica: C : superconductivity
T2 –, 4th International Conferene on Vortex Matter in Nanostructured, Superconductors (VORTEX IV), SEP 03-09, 2005, Iraklion, GREECE 437-38, 213 (2006). http://doi.org/10.1016/j.physc.2005.12.036
Abstract: Here we summarize results from our study of the critical depinning current J(c) versus the applied magnetic flux Phi, for: (i) quasiperiodic (QP) one-dimensional (1D) chains and (ii) 2D arrays of pinning centers placed on the nodes of a five-fold Penrose lattice. In 1D QP chains, the peaks in J(c)(Phi) are determined by a sequence of harmonics of the long and short segments of the chain. The critical current J(c)(Phi) has a remarkable self-similarity. In 2D QP pinning arrays, we predict analytically and numerically the main features of J(c)(Phi), and demonstrate that the Penrose lattice of pinning sites provides an enormous enhancement of J(c)(Phi), even compared to triangular and random pinning site arrays. This huge increase in J(c)(Phi) could be useful for applications. (c) 2005 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.404
Times cited: 6
DOI: 10.1016/j.physc.2005.12.036
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“Negative differential resistivity in superconductors with periodic arrays of pinning sites”. Misko VR, Savel'ev S, Rakhmanov AL, Nori F, Physical review : B : condensed matter and materials physics 75, 024509 (2007). http://doi.org/10.1103/PhysRevB.75.024509
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 28
DOI: 10.1103/PhysRevB.75.024509
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“Nonuniform self-organized dynamical states in superconductors with periodic pinning”. Misko VR, Savel'ev S, Rakhmanov AL, Nori F, Physical review letters 96, 127004 (2006). http://doi.org/10.1103/PhysRevLett.96.127004
Abstract: We consider magnetic flux moving in superconductors with periodic pinning arrays. We show that sample heating by moving vortices produces negative differential resistivity (NDR) of both N and S type (i.e., N- and S-shaped) in the voltage-current characteristic (VI curve). The uniform flux flow state is unstable in the NDR region of the VI curve. Domain structures appear during the NDR part of the VI curve of an N type, while a filamentary instability is observed for the NDR of an S type. The simultaneous existence of the NDR of both types gives rise to the appearance of striking self-organized (both stationary and nonstationary) two-dimensional dynamical structures.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 8.462
Times cited: 31
DOI: 10.1103/PhysRevLett.96.127004
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“Formation and size dependence of vortex shells in mesoscopic superconducting niobium disks”. Misko VR, Xu B, Peeters FM, Physical review : B : condensed matter and materials physics 76, 024516 (2007). http://doi.org/10.1103/PhysRevB.76.024516
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 33
DOI: 10.1103/PhysRevB.76.024516
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“Size-dependence of vortex shells in mesoscopic superconducting disks”. Misko VR, Xu B, Peeters FM, Physica: C : superconductivity 468, 726 (2008). http://doi.org/10.1016/j.physc.2007.11.036
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.404
Times cited: 9
DOI: 10.1016/j.physc.2007.11.036
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“Formation of vortex shells in mesoscopic superconducting squares”. Misko VR, Zhao HJ, Peeters FM, Oboznov V, Dubonos SV, Grigorieva IV, Superconductor science and technology 22, 034001 (2009). http://doi.org/10.1088/0953-2048/22/3/034001
Abstract: We study vortex configurations in mesoscopic superconducting squares. Our theoretical approach is based on the analytical solution of the London equation using the Green's function method. The potential energy landscape found is then used in Langevin-type molecular-dynamics simulations to obtain stable vortex configurations. We show that the filling rules for vortices in squares with increasing applied magnetic field can be formulated, although in a different manner than in disks, in terms of the formation of vortex 'shells'. We discuss metastable states and the stability of the vortex configurations found with respect to variations of the material parameters and deformations of the shape of the sample.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.878
Times cited: 14
DOI: 10.1088/0953-2048/22/3/034001
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“Spin- and valley-dependent miniband structure and transport in silicene superlattices”. Missault N, Vasilopoulos P, Peeters FM, Van Duppen B, Physical review B 93, 125425 (2016). http://doi.org/10.1103/PhysRevB.93.125425
Abstract: We investigate silicene superlattices in the presence of a tunable barrier potential U, an exchange field M, and a perpendicular electric field E-z. The resulting miniband structure depends on the spin and valley indices and on the fields M and E-z. These fields determine the minigaps and also affect the additional Dirac points brought about by the periodic potential U. In addition, we consider diffusive transport and assess its dependence on the spin and valley indices as well as on temperature. The corresponding spin and valley polarizations strongly depend on the potential U and can be made almost 100% at very low temperatures at particular values of the Fermi energy.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 49
DOI: 10.1103/PhysRevB.93.125425
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“Spin- and valley-dependent transport through arrays of ferromagnetic silicene junctions”. Missault N, Vasilopoulos P, Vargiamidis V, Peeters FM, Van Duppen B, Physical review : B : condensed matter and materials physics 92, 195423 (2015). http://doi.org/10.1103/PhysRevB.92.195423
Abstract: We study ballistic transport of Dirac fermions in silicene through arrays of barriers, of width d, in the presence of an exchange field M and a tunable potential of height U or depth-U. The spin-and valley-resolved conductances as functions of U or M, exhibit resonances away from the Dirac point (DP) and close to it a pronounced dip that becomes a gap when a critical electric field E-z is applied. This gap widens by increasing the number of barriers and can be used to realize electric field-controlled switching of the current. The spin p(s) and valley p(v) polarizations of the current near the DP increase with Ez or M and can reach 100% for certain of their values. These field ranges widen significantly by increasing the number of barriers. Also, ps and pv oscillate nearly periodically with the separation between barriers or wells and can be inverted by reversing M.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 54
DOI: 10.1103/PhysRevB.92.195423
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“Optical-quality controllable wet-chemical doping of graphene through a uniform, transparent and low-roughness F4-TCNQ/MEK layer”. Misseeuw L, Krajewska A, Pasternak I, Ciuk T, Strupinski W, Reekmans G, Adriaensens P, Geldof D, Geldof D, Van Vlierberghe S, Thienpont H, Dubruelf P, Vermeulen N, RSC advances , 104491 (2016). http://doi.org/10.1039/C6RA24057G
Abstract: Controllable chemical doping of graphene has already proven very useful for electronic applications, but when turning to optical and photonic applications, the additional requirement of having both a high transparency and a low surface roughness has, to our knowledge, not yet been fulfilled by any chemical dopant system reported so far. In this work, a new method that meets for the first time this opticalquality requirement while also providing efficient, controllable doping is presented. The method relies on F4-TCNQ dissolved in methyl ethyl ketone (MEK) yielding a uniform deposition after spin coating because of an extraordinary charge transfer interaction between the F4-TCNQ and MEK molecules. The formed F4-TCNQ/MEK layer exhibits a very high surface quality and optical transparency over the visible-infrared wavelength range between 550 and 1900 nm. By varying the dopant concentration of F4-TCNQ from 2.5 to 40 mg ml1 MEK, the doping effect can be controlled between Dn ¼ +5.73 1012 cm2 and +1.09 1013 cm2 for initially strongly p-type hydrogen-intercalated graphene grown on 6Hsilicon- carbide substrates, and between Dn ¼ +5.56 1012 cm2 and +1.04 1013 cm2 for initially weakly p-type graphene transferred on silicon samples. This is the first time that truly optical-quality chemical doping of graphene is demonstrated, and the obtained doping values exceed those reported before for F4-TCNQ-based graphene doping by as much as 50%.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1039/C6RA24057G
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“Polytypism in mcalpineite : a study of natural and synthetic Cu₃TeO₆”. Missen OP, Mills SJ, Canossa S, Hadermann J, Nenert G, Weil M, Libowitzky E, Housley RM, Artner W, Kampf AR, Rumsey MS, Spratt J, Momma K, Dunstan MA, Acta Crystallographica. Section B: Structural Science, Crystal Engineering and Materials (Online) 78 (2022). http://doi.org/10.1107/S2052520621013032
Abstract: Synthetic and naturally occurring forms of tricopper orthotellurate, (Cu3TeO6)-Te-II-O-IV (the mineral mcalpineite) have been investigated by 3D electron diffraction (3D ED), X-ray powder diffraction (XRPD), Raman and infrared (IR) spectroscopic measurements. As a result of the diffraction analyses, (Cu3TeO6)-Te-II-O-IV is shown to occur in two polytypes. The higher-symmetric (Cu3TeO6)-Te-II-O-IV-1C polytype is cubic, space group 1a (3) over bar, with a = 9.537 (1) angstrom and V = 867.4 (3) angstrom(3) as reported in previous studies. The 1C polytype is a well characterized structure consisting of alternating layers of (CuO6)-O-II octahedra and both (CuO6)-O-II and (TeO6)-O-VI octahedra in a patchwork arrangement. The structure of the lower-symmetric orthorhombic (Cu3TeO6)-Te-II-O-IV-2O polytype was determined for the first time in this study by 3D ED and verified by Rietveld refinement. The 2O polytype crystallizes in space group Pcca, with a = 9.745 (3) angstrom, b = 9.749 (2) angstrom, c = 9.771 (2) angstrom and V = 928.3 (4) angstrom(3) . High-precision XRPD data were also collected on (Cu3TeO6)-Te-II-O-IV-2O to verify the lower-symmetric structure by performing a Rietveld refinement. The resultant structure is identical to that determined by 3D ED, with unit-cell parameters a = 9.56157 (19) angstrom, b = 9.55853 (11) angstrom, c = 9.62891 (15) angstrom and V = 880.03 (2) angstrom(3) . The lower symmetry of the 2O polytype is a consequence of a different cation ordering arrangement, which involves the movement of every second (CuO6)-O-II and (TeO6)-O-VI octahedral layer by (1/4, 1/4, 0), leading to an offset of (TeO6)-O-VI and (CuO6)-O-II octahedra in every second layer giving an ABAB* stacking arrangement. Syntheses of (Cu3TeO6)-Te-II-O-IV showed that low-temperature (473 K) hydrothermal conditions generally produce the 2O polytype. XRPD measurements in combination with Raman spectroscopic analysis showed that most natural mcalpineite is the orthorhombic 2O polytype. Both XRPD and Raman spectroscopy measurements may be used to differentiate between the two polytypes of (Cu3TeO6)-Te-II-O-IV. In Raman spectroscopy, (Cu3TeO6)-Te-II-O-IV-1C has a single strong band around 730 cm(-1), whereas (Cu3TeO6)-Te-II-O-IV-2O shows a broad double maximum with bands centred around 692 and 742 cm(-1).
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.9
DOI: 10.1107/S2052520621013032
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“Oxide superconductors: electron microscopy”. Mitchell TE, Gronsky R, Van Tendeloo G Pergamon Press, Oxford, page 401 (1992).
Keywords: H3 Book chapter; Electron microscopy for materials research (EMAT)
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“Influence of the substrate orientation on the electronic and optical properties of InAs/GaAs quantum dots”. Mlinar V, Peeters FM, Applied physics letters 89, 1 (2006). http://doi.org/10.1063/1.2424435
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 16
DOI: 10.1063/1.2424435
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“Optical properties of (In,Ga)As capped InAs quantum dots grown on [11k] substrates”. Mlinar V, Peeters FM, Applied physics letters 91, 021910 (2007). http://doi.org/10.1063/1.2753745
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 9
DOI: 10.1063/1.2753745
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“Theoretical study of InAs/GaAs quantum dots grown on [11k] substrates in the presence of a magnetic field”. Mlinar V, Peeters FM, Microelectronics journal 37, 1427 (2006). http://doi.org/10.1016/j.mejo.2006.05.018
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.163
DOI: 10.1016/j.mejo.2006.05.018
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“A three-dimensional model for artificial atoms and molecules: influence of substrate orientation and magnetic field dependence”. Mlinar V, Peeters FM, Journal of materials chemistry 17, 3687 (2007). http://doi.org/10.1039/b701231d
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Times cited: 7
DOI: 10.1039/b701231d
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“Tuning of the optical properties of (11k) grown InAs quantum dots by the capping layer”. Mlinar V, Peeters FM, Microelectronics journal 39, 359 (2008). http://doi.org/10.1016/j.mejo.2007.07.052
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.163
DOI: 10.1016/j.mejo.2007.07.052
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“Theoretical study of electronic and optical properties of inverted GaAs/AlxGa1-xAs quantum dots with smoothed interfaces in an external magnetic field”. Mlinar V, Schliwa A, Bimberg D, Peeters FM, Physical review : B : condensed matter and materials physics 75, 205308 (2007). http://doi.org/10.1103/PhysRevB.75.205308
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 14
DOI: 10.1103/PhysRevB.75.205308
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“Nonsymmetrized Hamiltonian for semiconducting nanostructures in a magnetic field”. Mlinar V, Tadić, M, Partoens B, Peeters FM, Physical review : B : condensed matter and materials physics 71, 205305 (2005). http://doi.org/10.1103/PhysRevB.71.205305
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 37
DOI: 10.1103/PhysRevB.71.205305
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“Hole and exciton energy levels in InP/InxGa1-xP quantum dot molecules: influence of geometry and magnetic field dependence”. Mlinar V, Tadić, M, Peeters FM, Physical review : B : condensed matter and materials physics 73, 235336 (2006). http://doi.org/10.1103/PhysRevB.73.235336
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 16
DOI: 10.1103/PhysRevB.73.235336
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“Elemental and ionic components of atmospheric aerosols and associated gaseous pollutants in and near Dar es Salaam, Tanzania”. Mmari AG, Potgieter-Vermaak SS, Bencs L, McCrindle RI, Van Grieken R, Atmospheric environment : an international journal 77, 51 (2013). http://doi.org/10.1016/J.ATMOSENV.2013.04.061
Abstract: Elemental and water-soluble ionic compounds (WSICs) of atmospheric aerosols (total suspended particulate TSP) and some gaseous pollutants (SO2, NO2 and O3) from a coastal, semi-urban and rural site in and near Dar es Salaam, Tanzania were investigated during dry and wet seasons of January 2005November 2007. Na+, Ca2+, SO42−, NO3− and Cl− made up the dominant fraction of WSICs during the dry season with average concentrations ranging from non-detectable (n.d.)5.4, 0.262.6, 0.7414.7, 0.41.5 and 1.13.4 μg m−3, respectively, while in the wet season, from n.d. up to 1.7, 1.2, 4.4, 2.1 and 3.0 μg m−3, respectively. The total air concentrations of the detected elements (Al, Si, S, Cl, K, Ca, Fe and Zn) showed seasonal and site-specific variation in the range of 7.526.6 with an average of 14.5 μg m−3. Most of the air concentrations of pollutants were observed to decrease with increasing distance from the coastal site, which is under urban and industrial pollutant emissions. Sulphur and nitrogen oxidation ratios during the dry season ranged from 0.08 to 0.91 and 0.013 to 0.049, respectively, while they were between 0.090.65 and 0.0020.095, respectively, in the wet season. These values indicate the photochemical oxidation of SO2 and a high extent of NO3−formation in the atmosphere. Neutralization ratios revealed the presence of acidic SO42− and NO3− aerosols. Principal component analysis identified sea spray, local combustion, vehicular traffic, biomass burning and re-suspended road dust as dominant sources of aerosols at the studied coastal and semi-urban sites. However, at the rural site, besides sea spray, crustal sources, soil dust re-suspension and long-range transport are the possible origins of suspended particulates.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/J.ATMOSENV.2013.04.061
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“Corrosive marine atmosphere investigations in Tanzania: exposure sites and preliminary results”. Mmari AG, Potgieter-Vermaak SS, Uiso CBS, Makundi IN, Potgieter JH, Van Grieken R, Newsletter of the International Global Atmospheric Chemistry Project , 13 (2007)
Keywords: A3 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“Validation of inter-atomic potential for WS2 and WSe2 crystals through assessment of thermal transport properties”. Mobaraki A, Kandemir A, Yapicioglu H, Gulseren O, Sevik C, Computational materials science 144, 92 (2018). http://doi.org/10.1016/J.COMMATSCI.2017.12.005
Abstract: In recent years, transition metal dichalcogenides (TMDs) displaying astonishing properties are emerged as a new class of two-dimensional layered materials. The understanding and characterization of thermal transport in these materials are crucial for efficient engineering of 2D TMD materials for applications such as thermoelectric devices or overcoming general overheating issues. In this work, we obtain accurate Stillinger-Weber type empirical potential parameter sets for single-layer WS2 and WSe2 crystals by utilizing particle swarm optimization, a stochastic search algorithm. For both systems, our results are quite consistent with first-principles calculations in terms of bond distances, lattice parameters, elastic constants and vibrational properties. Using the generated potentials, we investigate the effect of temperature on phonon energies and phonon linewidth by employing spectral energy density analysis. We compare the calculated frequency shift with respect to temperature with corresponding experimental data, clearly demonstrating the accuracy of the generated inter-atomic potentials in this study. Also, we evaluate the lattice thermal conductivities of these materials by means of classical molecular dynamics simulations. The predicted thermal properties are in very good agreement with the ones calculated from first-principles. (C) 2017 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
DOI: 10.1016/J.COMMATSCI.2017.12.005
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“Temperature-dependent phonon spectrum of transition metal dichalcogenides calculated from the spectral energy density: Lattice thermal conductivity as an application”. Mobaraki A, Sevik C, Yapicioglu H, Cakir D, Gulseren O, Physical review B 100, 035402 (2019). http://doi.org/10.1103/PHYSREVB.100.035402
Abstract: Predicting the mechanical and thermal properties of quasi-two-dimensional (2D) transition metal dichalco-genides (TMDs) is an essential task necessary for their implementation in device applications. Although rigorous density-functional-theory-based calculations are able to predict mechanical and electronic properties, mostly they are limited to zero temperature. Classical molecular dynamics facilitates the investigation of temperature-dependent properties, but its performance highly depends on the potential used for defining interactions between the atoms. In this study, we calculated temperature-dependent phonon properties of single-layer TMDs, namely, MoS2, MoSe2, WS2, and WSe2, by utilizing Stillinger-Weber-type potentials with optimized sets of parameters with respect to the first-principles results. The phonon lifetimes and contribution of each phonon mode in thermal conductivities in these monolayer crystals are systematically investigated by means of the spectralenergy-density method based on molecular dynamics simulations. The obtained results from this approach are in good agreement with previously available results from the Green-Kubo method. Moreover, detailed analysis of lattice thermal conductivity, including temperature-dependent mode decomposition through the entire Brillouin zone, shed more light on the thermal properties of these 2D crystals. The LA and TA acoustic branches contribute most to the lattice thermal conductivity, while ZA mode contribution is less because of the quadratic dispersion around the Brillouin zone center, particularly in MoSe2 due to the phonon anharmonicity, evident from the redshift, especially in optical modes, by increasing temperature. For all the considered 2D crystals, the phonon lifetime values are compelled by transition metal atoms, whereas the group velocity spectrum is dictated by chalcogen atoms. Overall, the lattice thermal conductivity is linearly proportional with inverse temperature.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
DOI: 10.1103/PHYSREVB.100.035402
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“Atomically thin micas as proton-conducting membranes”. Mogg L, Hao G-P, Zhang S, Bacaksiz C, Zou Y, Haigh SJ, Peeters FM, Geim AK, Lozada-Hidalgo M, Nature nanotechnology 14, 962 (2019). http://doi.org/10.1038/S41565-019-0536-5
Abstract: Monolayers of graphene and hexagonal boron nitride (hBN) are highly permeable to thermal protons1,2. For thicker two-dimensional (2D) materials, proton conductivity diminishes exponentially, so that, for example, monolayer MoS2 that is just three atoms thick is completely impermeable to protons1. This seemed to suggest that only one-atom-thick crystals could be used as proton-conducting membranes. Here, we show that few-layer micas that are rather thick on the atomic scale become excellent proton conductors if native cations are ion-exchanged for protons. Their areal conductivity exceeds that of graphene and hBN by one to two orders of magnitude. Importantly, ion-exchanged 2D micas exhibit this high conductivity inside the infamous gap for proton-conducting materials3, which extends from ∼100 °C to 500 °C. Areal conductivity of proton-exchanged monolayer micas can reach above 100 S cm−2 at 500 °C, well above the current requirements for the industry roadmap4. We attribute the fast proton permeation to ~5-Å-wide tubular channels that perforate micas’ crystal structure, which, after ion exchange, contain only hydroxyl groups inside. Our work indicates that there could be other 2D crystals5 with similar nanometre-scale channels, which could help close the materials gap in proton-conducting applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 38.986
Times cited: 44
DOI: 10.1038/S41565-019-0536-5
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“Synthesis and characterization of a highly electroactive composite based on Au nanoparticles supported on nanoporous activated carbon for electrocatalysis”. Moggia G, Hoekx S, Daems N, Bals S, Breugelmans T, ChemElectroChem , 1 (2023). http://doi.org/10.1002/CELC.202300293
Abstract: A facile, “one-pot”, chemical approach to synthesize gold-based nanoparticles finely dispersed on porous activated carbon (Norit) was demonstrated in this work. The pH of the synthesis bath played a critical role in determining the optimal gold-carbon interaction, which enabled a successful deposition of the gold nanoparticles onto the carbon matrix with a maximized metal utilization of 93 %. The obtained AuNP/C nanocomposite was characterized using SEM, HAADF-STEM electron tomography and electrochemical techniques. It was found that the Au nanoparticles, with diameters between 5 and 20 nm, were evenly distributed over the carbon matrix, both inside and outside the pores. Electrochemical characterization indicated that the composite had a very large electroactive surface area (EASA), as high as 282.4 m2 gAu-1. By exploiting its very high EASA, the catalyst was intended to boost the productivity of glucaric acid in the electrooxidation of its precursor, gluconic acid. However, cyclic voltammetry experiments revealed a very limited reactivity towards gluconic acid oxidation, due to the spacial hindrance of gluconic acid molecule which prevented diffusion inside the catalyst nanopores. On the other hand, the as-synthesized nanocomposite promises to be effective towards the ORR, and might thus find potential application as anode catalyst for fuel cells as well as for the scalability of all those electrochemical reactions involving small molecules with high diffusivity and catalysed by noble metals (i. e. CO2, CH4, N2, etc..). Electrocatalysis: Gold nanoparticles with diameter between 5 and 20 nm evenly distributed onto porous activated carbon (Norit) were obtained using a facile “one-pot” chemical synthesis technique with very high metal utilization. The AuNP/C nanocomposite was characterized using SEM, HAADF-STEM electron tomography and electrochemical techniques, revealing a very large electroactive surface area (EASA). The figure shows the HAADF-STEM image (a) and the respective EDX elemental distribution (b) for the AuNP/C composite with 9.3 % Au-loading developed in this work (Au is marked in red and C in green).image
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Applied Electrochemistry & Catalysis (ELCAT)
Impact Factor: 4
Times cited: 1
DOI: 10.1002/CELC.202300293
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“Electric-field induced quantum broadening of the characteristic energy level of traps in semiconductors and oxides”. Mohammed M, Verhulst AS, Verreck D, Van de Put M, Simoen E, Sorée B, Kaczer B, Degraeve R, Mocuta A, Collaert N, Thean A, Groeseneken G, Journal of applied physics 120, 245704 (2016). http://doi.org/10.1063/1.4972482
Abstract: The trap-assisted tunneling (TAT) current in tunnel field-effect transistors (TFETs) is one of the crucial factors degrading the sub-60 mV/dec sub-threshold swing. To correctly predict the TAT currents, an accurate description of the trap is required. Since electric fields in TFETs typically reach beyond 10(6) V/cm, there is a need to quantify the impact of such high field on the traps. We use a quantum mechanical implementation based on the modified transfer matrix method to obtain the trap energy level. We present the qualitative impact of electric field on different trap configurations, locations, and host materials, including both semiconductors and oxides. We determine that there is an electric-field related trap level shift and level broadening. We find that these electric-field induced quantum effects can enhance the trap emission rates. Published by AIP Publishing.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.068
Times cited: 6
DOI: 10.1063/1.4972482
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“Phonon-assisted tunneling in direct-bandgap semiconductors”. Mohammed M, Verhulst AS, Verreck D, Van de Put ML, Magnus W, Sorée B, Groeseneken G, Journal of applied physics 125, 015701 (2019). http://doi.org/10.1063/1.5044256
Abstract: In tunnel field-effect transistors, trap-assisted tunneling (TAT) is one of the probable causes for degraded subthreshold swing. The accurate quantum-mechanical (QM) assessment of TAT currents also requires a QM treatment of phonon-assisted tunneling (PAT) currents. Therefore, we present a multi-band PAT current formalism within the framework of the quantum transmitting boundary method. An envelope function approximation is used to construct the electron-phonon coupling terms corresponding to local Frohlich-based phonon-assisted inter-band tunneling in direct-bandgap III-V semiconductors. The PAT current density is studied in up to 100 nm long and 20 nm wide p-n diodes with the 2- and 15-band material description of our formalism. We observe an inefficient electron-phonon coupling across the tunneling junction. We further demonstrate the dependence of PAT currents on the device length, for our non-self-consistent formalism which neglects changes in the electron distribution function caused by the electron-phonon coupling. Finally, we discuss the differences in doping dependence between direct band-to-band tunneling and PAT current. Published under license by AIP Publishing.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.068
Times cited: 2
DOI: 10.1063/1.5044256
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