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“Quantitative measurement for the microstructural parameters of nano-precipitates in Al-Mg-Si-Cu alloys”. Li K, Idrissi H, Sha G, Song M, Lu J, Shi H, Wang W, Ringer SP, Du Y, Schryvers D, Materials characterization 118, 352 (2016). http://doi.org/10.1016/j.matchar.2016.06.007
Abstract: Size, number density and volume fraction of nano-precipitates are important microstructural parameters controlling the strengthening of materials. In this work a widely accessible, convenient, moderately time efficient method with acceptable accuracy and precision has been provided for measurement of volume fraction of nano-precipitates in crystalline materials. The method is based on the traditional but highly accurate technique of measuring foil thickness via convergent beam electron diffraction. A new equation is proposed and verified with the aid of 3-dimensional atom probe (3DAP) analysis, to compensate for the additional error resulted from the hardly distinguishable contrast of too short incomplete precipitates cut by the foil surface. The method can be performed on a regular foil specimen with a modem LaB6 or field-emission-gun transmission electron microscope. Precisions around +/- 16% have been obtained for precipitate volume fractions of needle-like beta ''/C and Q precipitates in an aged Al-Mg-Si-Cu alloy. The measured number density is dose to that directly obtained using 3DAP analysis by a misfit of 45%, and the estimated precision for number density measurement is about +/- 11%. The limitations of the method are also discussed.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 2.714
Times cited: 9
DOI: 10.1016/j.matchar.2016.06.007
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“Quantitative 3D analysis of huge nanoparticle assemblies”. Zanaga D, Bleichrodt F, Altantzis T, Winckelmans N, Palenstijn WJ, Sijbers J, de Nijs B, van Huis MA, Sanchez-Iglesias A, Liz-Marzan LM, van Blaaderen A, Joost Batenburg K, Bals S, Van Tendeloo G, Nanoscale 8, 292 (2016). http://doi.org/10.1039/c5nr06962a
Abstract: Nanoparticle assemblies can be investigated in 3 dimensions using electron tomography. However, it is not straightforward to obtain quantitative information such as the number of particles or their relative position. This becomes particularly difficult when the number of particles increases. We propose a novel approach in which prior information on the shape of the individual particles is exploited. It improves the quality of the reconstruction of these complex assemblies significantly. Moreover, this quantitative Sparse Sphere Reconstruction approach yields directly the number of particles and their position as an output of the reconstruction technique, enabling a detailed 3D analysis of assemblies with as many as 10 000 particles. The approach can also be used to reconstruct objects based on a very limited number of projections, which opens up possibilities to investigate beam sensitive assemblies where previous reconstructions with the available electron tomography techniques failed.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 7.367
Times cited: 34
DOI: 10.1039/c5nr06962a
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“Quantifying a Heterogeneous Ru Catalyst on Carbon Black Using ADF STEM”. Varambhia AM, Jones L, De Backer A, Fauske VT, Van Aert S, Ozkaya D, Nellist PD, Particle and particle systems characterization 33, 438 (2016). http://doi.org/10.1002/ppsc.201600067
Abstract: Ru catalysts are part of a set of late transition metal nanocatalysts that have garnered much interest for catalytic applications such as ammonia synthesis and fuel cell production. Their performance varies greatly depending on their morphology and size, these catalysts are widely studied using electron microscopy. Using recent developments in Annular Dark Field (ADF) Scanning Transmission Electron Microscopy (STEM) quantification techniques, a rapid atom counting procedure was utilized to document the evolution of a heterogeneous Ru catalyst supported on carbon black. Areas of the catalyst were imaged for approximately 15 minutes using ADF STEM. When the Ru clusters were exposed to the electron beam, the clusters changed phase from amorphous to crystalline. To quantify the thickness of the crystalline clusters, two techniques were applied (simulation and statistical decomposition) and compared. These techniques show that stable face centredcubic crystal structures in the form of rafts, between 2 and 8 atoms thick, were formed after the initial wetting of the carbon support.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.474
Times cited: 4
DOI: 10.1002/ppsc.201600067
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“Progress and new advances in simulating electron microscopy datasets using MULTEM”. Lobato I, Van Aert S, Verbeeck J, Ultramicroscopy 168, 17 (2016). http://doi.org/10.1016/j.ultramic.2016.06.003
Abstract: A new version of the open source program MULTEM is presented here. It includes a graphical user interface, tapering truncation of the atomic potential, CPU multithreading functionality, single/double precision calculations, scanning transmission electron microscopy (STEM) simulations using experimental detector sensitivities, imaging STEM (ISTEM) simulations, energy filtered transmission electron microscopy (EFTEM) simulations, STEM electron energy loss spectroscopy (EELS) simulations along with other improvements in the algorithms. We also present a mixed channeling approach for the calculation of inelastic excitations, which allows one to considerably speed up time consuming EFTEM/STEM-EELS calculations.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.843
Times cited: 43
DOI: 10.1016/j.ultramic.2016.06.003
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“Production of carboxylates from high rate activated sludge through fermentation”. Cagnetta C, Coma M, Vlaeminck SE, Rabaey K, Bioresource technology 217, 165 (2016). http://doi.org/10.1016/J.BIORTECH.2016.03.053
Abstract: The aim of this work was to study the key parameters affecting fermentation of high rate activated A-sludge to carboxylates, including pH, temperature, inoculum, sludge composition and iron content. The maximum volatile fatty acids production was 141 mg C g−1 VSSfed, at pH 7. Subsequently the potential for carboxylate and methane production for A-sludge from four different plants at pH 7 and 35 °C were compared. Initial BOD of the sludge appeared to be key determining carboxylate yield from A-sludge. Whereas methanogenesis could be correlated linearly to the quantity of ferric used for coagulation, fermentation did not show a dependency on iron presence. This difference may enable a strategy whereby A-stage sludge is separated to achieve fermentation, and iron dosing for phosphate removal is only implemented at the B-stage.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.BIORTECH.2016.03.053
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“Probing the electrochemical behavior of {111} and {110} faceted hollow Cu2O microspheres for lithium storage”. Yu W-B, Hu Z-Y, Yi M, Huang S-Z, Chen D-S, Jin J, Li Y, Van Tendeloo G, Su B-L, RSC advances 6, 97129 (2016). http://doi.org/10.1039/C6RA21026K
Abstract: Transition metal oxides with exposed highly active facets have become of increasing interest as anode materials for lithium ion batteries, because more dangling atoms exposed at the active surface facilitate the reaction between the transition metal oxides and lithium. In this work, we probed the electrochemical behavior of hollow Cu2O microspheres with {111} and {110} active facets on the polyhedron surface as anodes for lithium storage. Compared to commercial Cu2O nanoparticles, hollow Cu2O microspheres with {111} and {110} active facets show a rising specific capacity at 30 cycles which then decreases after 110 cycles during the cycling process. Via advanced electron microscopy characterization, we reveal that this phenomenon can be attributed to the highly active {111} and {110} facets with dangling “Cu” atoms facilitating the conversion reaction of Cu2O and Li, where part of the Cu2O is oxidized to CuO during the charging process. However, as the reaction proceeds, more and more formed Cu nanoparticles cannot be converted to Cu2O or CuO. This leads to a decrease of the specific capacity. We believe that our study here sheds some light on the progress of the electrochemical behavior of transition metal oxides with respect to their increased specific capacity and the subsequent decrease via a conversion reaction mechanism. These results will be helpful to optimize the design of transition metal oxide micro/nanostructures for high performance lithium storage.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.108
Times cited: 5
DOI: 10.1039/C6RA21026K
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“Predicting saturated hydraulic conductivity in a sandy grassland using proximally sensed apparent electrical conductivity”. Rezaei M, Saey T, Seuntjens P, Joris I, Boenne W, Van Meirvenne M, Cornelis W, Journal of applied geophysics 126, 35 (2016). http://doi.org/10.1016/J.JAPPGEO.2016.01.010
Abstract: Finding a correspondence between soil hydraulic properties, such as saturated hydraulic conductivity (Ks) and apparent electrical conductivity (ECa) as an easily measurable parameter, may be a way forward to estimate the spatial distribution of hydraulic properties at the field scale. In this study, the spatial distributions of Ks, of soil ECa measured by a DUALEM-21S sensor and of soil physical properties were investigated in a sandy grassland. To predict field scale Ks, the statistical relationship between co-located soil Ks, and EMI-ECa was evaluated. Results demonstrated the large spatial variability of all studied properties with Ks being the most variable one (CV = 86.21%) followed by ECa (CV >= 53.77%). A significant negative correlation was found between In-transformed Ks and ECa (r = 0.83; P <= 0.01) at two depths of exploration (0-50 and 0-100 cm). This site specific relation between In Ks and ECa was used to predict saturated hydraulic conductivity over 0-50 cm depth for the whole field. The empirical relation was validated using an independent dataset of measured Ks. The statistical results demonstrate the robustness of this empirical relation with mean estimation error MEE = 0.46 (cm h(-1)), root-mean-square estimation errors RMSEE = 0.74 (cm h(-1)), coefficient of determination r(2) = 0.67 and coefficient of model efficiency Ce = 0.64. The relationship was then used to produce a detailed map of Ks for the whole field. The result will allow model predictions of spatially distributed water content in view of irrigation management. (C) 2016 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.JAPPGEO.2016.01.010
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“Post-synthesis bromination of benzene bridged PMO as a way to create a high potential hybrid material”. Huybrechts W, Mali G, Kuśtrowski P, Willhammar T, Mertens M, Bals S, Van Der Voort P, Cool P, Microporous and mesoporous materials: zeolites, clays, carbons and related materials 236, 244 (2016). http://doi.org/10.1016/j.micromeso.2016.09.003
Abstract: Periodic mesoporous organosilicas provide the best of two worlds: the strength and porosity of an inorganic framework combined with the infinite possibilities created by the organic bridging unit. In this work we focus on post-synthetical modification of benzene bridged PMO, in order to create bromobenzene PMO. In the past, this proved to be very challenging due to unwanted structural deterioration. However, now we have found a way to brominate this material whilst keeping the structure intact. In-depth structural analysis by solid state NMR and XPS shows both vast progress over previous attempts as well as potential for improvement.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA)
Impact Factor: 3.615
Times cited: 7
DOI: 10.1016/j.micromeso.2016.09.003
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“Positron surface state as a spectroscopic probe for characterizing surfaces of topological insulator materials”. Callewaert V, Shastry K, Saniz R, Makkonen I, Barbiellini B, Assaf BA, Heiman D, Moodera JS, Partoens B, Bansil A, Weiss AH;, Physical review B 94, 115411 (2016). http://doi.org/10.1103/PHYSREVB.94.115411
Abstract: Topological insulators are attracting considerable interest due to their potential for technological applications and as platforms for exploring wide-ranging fundamental science questions. In order to exploit, fine-tune, control, and manipulate the topological surface states, spectroscopic tools which can effectively probe their properties are of key importance. Here, we demonstrate that positrons provide a sensitive probe for topological states and that the associated annihilation spectrum provides a technique for characterizing these states. Firm experimental evidence for the existence of a positron surface state near Bi2Te2Se with a binding energy of E-b = 2.7 +/- 0.2 eV is presented and is confirmed by first-principles calculations. Additionally, the simulations predict a significant signal originating from annihilation with the topological surface states and show the feasibility to detect their spin texture through the use of spin-polarized positron beams.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 15
DOI: 10.1103/PHYSREVB.94.115411
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“Polydopamine-gelatin as universal cell-interactive coating for methacrylate-based medical device packaging materials : when surface chemistry overrules substrate bulk properties”. Van de Walle E, Van Nieuwenhove I, Vanderleyden E, Declercq H, Gellynck K, Schaubroeck D, Ottevaere H, Thienpont H, De Vos WH, Cornelissen M, Van Vlierberghe S, Dubruel P, Biomacromolecules 17, 56 (2016). http://doi.org/10.1021/ACS.BIOMAC.5B01094
Abstract: Despite its widespread application in the fields of ophthalmology, orthopedics and dentistry and the stringent need for polymer packagings that induce in vivo tissue integration, the full potential of poly(methyl methacrylate) (PMMA) and its derivatives as medical device packaging material has not been explored yet. We therefore elaborated on the development of a universal coating for methacrylate-based materials which ideally should reveal cell-interactivity irrespective of the polymer substrate bulk properties. Within this perspective, the present work reports on the UV-induced synthesis of PMMA and its more flexible poly(ethyleneglycol) (PEG)-based derivative (PMMAPEG) and its subsequent surface decoration using polydopamine (PDA) as well as PDA combined with gelatin B (Gel B). Successful application of both layers was confirmed by multiple surface characterization techniques. The cell interactivity of the materials was studied by performing live-dead assays and immunostainings of the cytoskeletal components of fibroblasts. It can be concluded that only the combination of PDA and Gel B yields materials posessing similar cell interactivities, irrespective of the physicochemical properties of the underlying substrate. The proposed coating outperforms both the PDA functionalized and the pristine polymer surfaces. A universal cell-interactive coating for methacrylate-based medical device packaging materials has thus been realized.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1021/ACS.BIOMAC.5B01094
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Van Duppen B (2016) Plasmonics in graphene and related materials. Antwerpen
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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“Plasmonic ‘rainbow&rsquo, photocatalyst with broadband solar light response for environmental applications”. Verbruggen SW, Keulemans M, Goris B, Blommaerts N, Bals S, Martens JA, Lenaerts S, Applied catalysis : B : environmental 188, 147 (2016). http://doi.org/10.1016/j.apcatb.2016.02.002
Abstract: We propose the concept of a ‘rainbow’ photocatalyst that consists of TiO2 modified with gold-silver alloy nanoparticles of various sizes and compositions, resulting in a broad plasmon absorption band that covers the entire UV–vis range of the solar spectrum. It is demonstrated that this plasmonic ‘rainbow’ photocatalyst is 16% more effective than TiO2 P25 under both simulated and real solar light for pollutant degradation at the solid-gas interface. With this we provide a promising strategy to maximize the spectral response for solar to chemical energy conversion.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 9.446
Times cited: 47
DOI: 10.1016/j.apcatb.2016.02.002
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“Plasmonic Au@Pd Nanorods with Boosted Refractive Index Susceptibility and SERS Efficiency: A Multifunctional Platform for Hydrogen Sensing and Monitoring of Catalytic Reactions”. Rodal-Cedeira S, Montes-García V, Polavarapu L, Solís DM, Heidari H, La Porta A, Angiola M, Martucci A, Taboada JM, Obelleiro F, Bals S, Pérez-Juste J, Pastoriza-Santos I, Chemistry of materials 28, 9169 (2016). http://doi.org/10.1021/acs.chemmater.6b04941
Abstract: Palladium nanoparticles (NPs) have received tremendous attention over the years due to their high catalytic activity for various chemical reactions. However, unlike other noble metal nanoparticles such as Au and Ag NPs, they exhibit poor plasmonic properties with broad extinction spectra and less scattering efficiency, and thus limiting their applications in the field of plasmonics. Therefore, it has been challenging to integrate tunable and strong plasmonic properties into catalytic Pd nanoparticles. Here we show that plasmonic Au@Pd nanorods (NRs) with relatively narrow and remarkably tunable optical responses in the NIR region can be obtained by directional growth of Pd on penta-twinned Au NR seeds. We found the presence of bromide ions facilitates the stabilization of facets for the directional growth of Pd shell to obtain Au@Pd nanorods (NR) with controlled length scales. Interestingly, it turns out the Au NR supported Pd NRs exhibit much narrow extinction compared to pure Pd NRs, which makes them suitable for plasmonic sensing applications. Moreover, these nanostructures display, to the best of our knowledge, one of the highest ensemble refractive index sensitivity values reported to date (1067 nm per refractive index unit, RIU). Additionally, we showed the application of such plasmonic Au@Pd NRs for localized surface plasmon resonance (LSPR)-based sensing of hydrogen both in solution as well as on substrate. Finally, we demonstrate the integration of excellent plasmonic properties in catalytic palladium enables the in situ monitoring of a reaction progress by surface-enhanced Raman scattering. We postulate the proposed approach to boost the plasmonic properties of Pd nanoparticles will ignite the design of complex shaped plasmonic Pd NPs to be used in various plasmonic applications such as sensing and in situ monitoring of various chemical reactions.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 80
DOI: 10.1021/acs.chemmater.6b04941
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“Plasma–liquid interactions: a review and roadmap”. Bruggeman PJ, Kushner MJ, Locke BR, Gardeniers JGE, Graham WG, Graves DB, Hofman-Caris RCHM, Maric D, Reid JP, Ceriani E, Fernandez Rivas D, Foster JE, Garrick SC, Gorbanev Y, Hamaguchi S, Iza F, Jablonowski H, Klimova E, Kolb J, Krcma F, Lukes P, Machala Z, Marinov I, Mariotti D, Mededovic Thagard S, Minakata D, Neyts EC, Pawlat J, Petrovic ZL, Pflieger R, Reuter S, Schram DC, Schröter S, Shiraiwa M, Tarabová, B, Tsai PA, Verlet JRR, von Woedtke T, Wilson KR, Yasui K, Zvereva G, Plasma sources science and technology 25, 053002 (2016). http://doi.org/10.1088/0963-0252/25/5/053002
Abstract: Plasma–liquid interactions represent a growing interdisciplinary area of research involving plasma science, fluid dynamics, heat and mass transfer, photolysis, multiphase chemistry and aerosol science. This review provides an assessment of the state-of-the-art of this multidisciplinary area and identifies the key research challenges. The developments in diagnostics, modeling and further extensions of cross section and reaction rate databases that are necessary to address these challenges are discussed. The review focusses on nonequilibrium plasmas.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.302
Times cited: 460
DOI: 10.1088/0963-0252/25/5/053002
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“Plasma-Surface Interactions in Plasma Catalysis”. Neyts EC, Plasma chemistry and plasma processing 36, 185 (2016). http://doi.org/10.1007/s11090-015-9662-5
Abstract: In this paper the various elementary plasma—surface interaction processes occurring in plasma catalysis are critically evaluated. Specifically, plasma catalysis at atmospheric pressure is considered. The importance of the various processes is analyzed for the most common plasma catalysis sources, viz. the dielectric barrier discharge and the gliding arc. The role and importance of surface chemical reactions (including adsorption, surface-mediated association and dissociation reactions, and desorption), plasma-induced surface modification, photocatalyst activation, heating, charging, surface discharge formation and electric field enhancement are discussed in the context of plasma catalysis. Numerous examples are provided to demonstrate the importance of the various processes.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.355
Times cited: 66
DOI: 10.1007/s11090-015-9662-5
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“Plasma processes and polymers third special issue on plasma and cancer”. Laroussi M, Bogaerts A, Barekzi N, Plasma processes and polymers 13, 1142 (2016). http://doi.org/10.1002/ppap.201600193
Keywords: Editorial; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.846
Times cited: 1
DOI: 10.1002/ppap.201600193
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Van Wesenbeeck K (2016) Plasma catalysis as an efficient and sustainable air purification technology. 171 p
Keywords: Doctoral thesis; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
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“Plasma based co2 conversion: a combined modeling and experimental study”. Bogaerts A, Snoeckx R, Berthelot A, Heijkers S, Wang W, Sun S, Van Laer K, Ramakers M, Michielsen I, Uytdenhouwen Y, Meynen V, Cool P, Hakone Xv: International Symposium On High Pressure Low Temperature Plasma Chemistry: With Joint Cost Td1208 Workshop: Non-equilibrium Plasmas With Liquids For Water And Surface Treatment (2016)
Abstract: In recent years there is increased interest in plasma-based CO2 conversion. Several plasma setups are being investigated for this purpose, but the most commonly used ones are a dielectric barrier discharge (DBD), a microwave (MW) plasma and a gliding arc (GA) reactor. In this proceedings paper, we will show results from our experiments in a (packed bed) DBD reactor and in a vortex-flow GA reactor, as well as from our model calculations for the detailed plasma chemistry in a DBD, MW and GA, for pure CO2 as well as mixtures of CO2 with N-2, CH4 and H2O.
Keywords: P1 Proceeding; Laboratory of adsorption and catalysis (LADCA); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
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“Piezoelectricity in asymmetrically strained bilayer graphene”. Van der Donck M, De Beule C, Partoens B, Peeters FM, Van Duppen B, 2D materials 3, 035015 (2016). http://doi.org/10.1088/2053-1583/3/3/035015
Abstract: We study the electronic properties of commensurate faulted bilayer graphene by diagonalizing the one-particle Hamiltonian of the bilayer system in a complete basis of Bloch states of the individual graphene layers. Our novel approach is very general and can be easily extended to any commensurate graphene-based heterostructure. Here, we consider three cases: (i) twisted bilayer graphene, (ii) bilayer graphene where triaxial stress is applied to one layer and (iii) bilayer graphene where uniaxial stress is applied to one layer. We show that the resulting superstructures can be divided into distinct classes, depending on the twist angle or the magnitude of the induced strain. The different classes are distinguished from each other by the interlayer coupling mechanism, resulting in fundamentally different low-energy physics. For the cases of triaxial and uniaxial stress, the individual graphene layers tend to decouple and we find significant charge transfer between the layers. In addition, this piezoelectric effect can be tuned by applying a perpendicular electric field. Finally, we show how our approach can be generalized to multilayer systems.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 6.937
Times cited: 10
DOI: 10.1088/2053-1583/3/3/035015
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“Phase transition and spin-resolved transport in MoS2 nanoribbons”. Heshmati-Moulai A, Simchi H, Esmaeilzadeh M, Peeters FM, Physical review B 94, 235424 (2016). http://doi.org/10.1103/PHYSREVB.94.235424
Abstract: The electronic structure and transport properties of monolayer MoS2 are studied using a tight-binding approach coupled with the nonequilibrium Green's function method. A zigzag nanoribbon of MoS2 is conducting due to the intersection of the edge states with the Fermi level that is located within the bulk gap. We show that applying a transverse electric field results in the disappearance of this intersection and turns the material into a semiconductor. By increasing the electric field the band gap undergoes a two stage linear increase after which it decreases and ultimately closes. It is shown that in the presence of a uniform exchange field, this electric field tuning of the gap can be exploited to open low energy domains where only one of the spin states contributes to the electronic conductance. This introduces possibilities in designing spin filters for spintronic applications.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 7
DOI: 10.1103/PHYSREVB.94.235424
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“Phase formation and texture of thin nickel germanides on Ge(001) and Ge(111)”. De Schutter B, Van Stiphout K, Santos NM, Bladt E, Jordan-Sweet J, Bals S, Lavoie C, Comrie CM, Vantomme A, Detavernier C, Journal of applied physics 119, 135305 (2016). http://doi.org/10.1063/1.4945317
Abstract: We studied the solid-phase reaction between a thin Nifilm and a single crystal Ge(001) or Ge(111) substrate during a ramp anneal. The phase formation sequence was determined using in situX-ray diffraction and in situRutherford backscattering spectrometry (RBS), while the nature and the texture of the phases were studied using X-ray pole figures and transmission electron microscopy. The phase sequence is characterized by the formation of a single transient phase before NiGe forms as the final and stable phase. X-ray pole figures were used to unambiguously identify the transient phase as the ϵ-phase, a non-stoichiometric Ni-rich germanide with a hexagonal crystal structure that can exist for Ge concentrations between 34% and 48% and which forms with a different epitaxial texture on both substrate orientations. The complementary information gained from both RBS and X-ray pole figure measurements revealed a simultaneous growth of both the ϵ-phase and NiGe over a small temperature window on both substrate orientations.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.068
Times cited: 14
DOI: 10.1063/1.4945317
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“Peculiar piezoelectric properties of soft two-dimensional materials”. Sevik C, Çakir D, Gulseren O, Peeters FM, The journal of physical chemistry: C : nanomaterials and interfaces 120, 13948 (2016). http://doi.org/10.1021/acs.jpcc.6b03543
Abstract: Group II-VI semiconductor honeycomb monolayers have a noncentrosymmetric crystal structure and therefore are expected to be important for nano piezoelectric device applications. This motivated us to perform first principles calculations based on density functional theory to unveil the piezoelectric properties (i.e., piezoelectric stress (e(11)) and piezoelectric strain (d(11)) coefficients) of these monolayer materials with chemical formula MX (where M = Be, Mg, Ca, Sr, Ba, Zr, Cd and X = S, Se, Te). We found that these two-dimensional materials have peculiar piezoelectric properties with d(11) coefficients 1 order of magnitude larger than those of commercially utilized bulk materials. A clear trend in their piezoelectric properties emerges, which
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 4.536
Times cited: 39
DOI: 10.1021/acs.jpcc.6b03543
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“Peculiar half-metallic state in zigzag nanoribbons of MoS2 : spin filtering”. Khoeini F, Shakouri, Peeters FM, Physical review B 94, 125412 (2016). http://doi.org/10.1103/PHYSREVB.94.125412
Abstract: Layered structures of molybdenum disulfide (MoS2) belong to a new class of two-dimensional (2D) semiconductor materials in which monolayers exhibit a direct band gap in their electronic spectrum. This band gap has recently been shown to vanish due to the presence of metallic edge modes when MoS2 monolayers are terminated by zigzag edges on both sides. Here, we demonstrate that a zigzag nanoribbon of MoS2, when exposed to an external exchange field in combination with a transverse electric field, has the potential to exhibit a peculiar half-metallic nature and thereby allows electrons of only one spin direction to move. The peculiarity of such spin-selective conductors originates from a spin switch near the gap-closing region, so the allowed spin orientation can be controlled by means of an external gate voltage. It is shown that the induced half-metallic phase is resistant to random fluctuations of the exchange field as well as the presence of edge vacancies.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 38
DOI: 10.1103/PHYSREVB.94.125412
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“PdPb-catalyzed decarboxylation of proline to pyrrolidine : highly selective formation of a biobased amine in water”. Verduyckt J, Van Hoof M, De Schouwer F, Wolberg M, Kurttepeli M, Eloy P, Gaigneaux EM, Bals S, Kirschhock CEA, De Vos DE, ACS catalysis 6, 7303 (2016). http://doi.org/10.1021/ACSCATAL.6B02561
Abstract: Amino acids have huge potential as platform chemicals in the biobased industry. Pd-catalyzed decarboxylation is a very promising route for the valorization of these natural compounds derived from protein waste or fermentation. We report that the highly abundant and nonessential amino acid L-proline is very reactive in the Pd-catalyzed decarboxylation. Full conversions are obtained with Pd/C and different Pd/MeOx catalysts; this allowed the identification of the different side reactions and the mapping of the reaction network. Due to the high reactivity of pyrrolidine, the selectivity for pyrrolidine was initially low. By carefully modifying Pd/ZrO2 with Pb in a controlled manner-via two incipient wetness impregnation steps-the selectivity increased remarkably. Finally, a thorough investigation of the reaction parameters resulted in an increased activity of this modified catalyst and an even further enhanced selectivity under a low H-2 pressure of 4 bar at 235 degrees C in water. This results in a very selective and sustainable production route for the highly interesting pyrrolidine.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 10.614
Times cited: 27
DOI: 10.1021/ACSCATAL.6B02561
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“PDMS membranes containing ZIF-coated mesoporous silica spheres for efficient ethanol recovery via pervaporation”. Naik PV, Wee LH, Meledina M, Turner S, Li Y, Van Tendeloo G, Martens JA, Vankelecom IFJ, Journal of materials chemistry A : materials for energy and sustainability 4, 12790 (2016). http://doi.org/10.1039/C6TA04700A
Abstract: The design of functional micro- and mesostructured composite materials is significantly important for separation processes. Mesoporous silica is an attractive material for fast diffusion, while microporous zeolitic imidazolate frameworks (ZIFs) are beneficial for selective adsorption and diffusion. In this work, ZIF-71 and ZIF-8 nanocrystals were grown on the surface of mesoporous silica spheres (MSS) via the seeding and regrowth approach in order to obtain monodispersed MSS-ZIF-71 and MSS-ZIF-8 spheres with a particle size of 2-3 mm. These MSS-ZIF spheres were uniformly dispersed into a polydimethylsiloxane (PDMS) matrix to prepare mixed matrix membranes (MMMs). These MMMs were evaluated for the separation of ethanol from water via pervaporation. The pervaporation results reveal that the MSS-ZIF filled MMMs substantially improve the ethanol recovery in both aspects viz. flux and separation factor. These MMMs outperforms the unfilled PDMS membranes and the conventional carbon and zeolite filled MMMs. As expected, the mesoporous silica core allows very fast flow of the permeating compound, while the hydrophobic ZIF coating enhances the ethanol selectivity through its specific pore structure, hydrophobicity and surface chemistry. It can be seen that ZIF-8 mainly has a positive impact on the selectivity, while ZIF-71 enhances fluxes more significantly.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 8.867
Times cited: 26
DOI: 10.1039/C6TA04700A
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“Pb2MnTeO6 double perovskite : an antipolar anti-ferromagnet”. Retuerto M, Skiadopoulou S, Li MR, Abakumov AM, Croft M, Ignatov A, Sarkar T, Abbett BM, Pokorný, J, Savinov M, Nuzhnyy D, Prokleška J, Abeykoon M, Stephens PW, Hodges JP, Vaněk P, Fennie CJ, Rabe KM, Kamba S, Greenblatt M;, Inorganic chemistry 55, 4320 (2016). http://doi.org/10.1021/acs.inorgchem.6b00054
Abstract: Pb2MnTeO6, a new double perovskite, was synthesized. Its crystal structure was determined by synchrotron X-ray and powder neutron diffraction. Pb2MnTeO6 is monoclinic (I2/m) at room temperature with a regular arrangement of all the cations in their polyhedra. However, when the temperature is lowered to similar to 120 K it undergoes a phase transition from I2/m to C2/c structure. This transition is accompanied by a displacement of the Pb atoms from the center of their polyhedra due to the 6s2 lone-pair electrons, together with a surprising off-centering of Mn2+ (d5) magnetic cations. This strong first-order phase transition is also evidenced by specific heat, dielectric, Raman, and infrared spectroscopy measurements. The magnetic characterizations indicate an anti-ferromagnetic (AFM) order below TN approximate to 20 K; analysis of powder neutron diffraction data confirms the magnetic structure with propagation vector k = (0 1 0) and collinear AFM spins. The observed jump in dielectric permittivity near similar to 150 K implies possible anti-ferroelectric behavior; however, the absence of switching suggests that Pb2MnTeO6 can only be antipolar. First-principle calculations confirmed that the crystal and magnetic structures determined are locally stable and that anti-ferroelectric switching is unlikely to be observed in Pb2MnTeO6.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.857
Times cited: 9
DOI: 10.1021/acs.inorgchem.6b00054
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“Particle transport through an inductively coupled plasma torch: elemental droplet evaporation”. Aghaei M, Bogaerts A, Journal of analytical atomic spectrometry 31, 631 (2016). http://doi.org/10.1039/C5JA00162E
Abstract: We studied the transport of copper droplets through an inductively coupled plasma, connected to the sampling cone of a mass spectrometer, by means of a computational model. The sample droplets are followed until they become evaporated. They are inserted as liquid particles from the central inlet and the effects of injection position (i.e. “on” and “off” axis), droplet diameter, as well as mass loading flow rate are investigated. It is shown that more “on-axis” injection of the droplets leads to a more straight path line, so that the droplets move less in the radial direction and are evaporated more on the central axis, enabling a better sample transfer efficiency to the sampler cone. Furthermore, there are optimum ranges of diameters and flow rates, which guarantee the proper position of evaporation along the torch, i.e. not too early, so that the sample can get lost in the torch, and not too late, which reduces the chance of becoming ionized before reaching the sampler.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.379
Times cited: 21
DOI: 10.1039/C5JA00162E
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“Overcoming the challenges for mainstream deammonification on municipal wastewater in warm and cold areas”. Mozo I, Lacoste L, Aussenac J, De Cocker P, Vlaeminck SE, Sperandio M, Caligaris M, Barillon B, Martin Ruel S, , 3 p.
T2 (2016)
Keywords: P3 Proceeding; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
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“Oscillatory behavior of the tunnel magnetoresistance due to thickness variations in Ta vertical bar CoFe vertical bar MgO magnetic tunnel junctions : a first-principles study”. Sankaran K, Swerts J, Couet S, Stokbro K, Pourtois G, Physical review B 94, 094424 (2016). http://doi.org/10.1103/PHYSREVB.94.094424
Abstract: To investigate the impact of both the CoFe ferromagnetic layer thickness and the capping paramagnetic layer on the tunnel magnetoresistance (TMR), we performed first-principles simulations on epitaxial magnetic tunnel junctions contacted with either CoFe or Ta paramagnetic capping layers. We observed a strong oscillation of the TMR amplitude with respect to the thickness of the ferromagnetic layer. The TMR is found to be amplified whenever the MgO spin tunnel barrier is thickened. Quantization of the electronic structure of the ferromagnetic layers is found to be at the origin of this oscillatory behavior. Metals such as Ta contacting the magnetic layer are found to enhance the amplitude of the oscillations due to the occurrence of an interface dipole. The latter drives the band alignment and tunes the nature of the spin channels that are active during the tunneling process. Subsequently, the regular transmission spin channels are modulated in the magnetic tunnel junction stack and other complex ones are being activated.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.836
Times cited: 4
DOI: 10.1103/PHYSREVB.94.094424
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“Origin of the performances degradation of two-dimensional-based metal-oxide-semiconductor field effect transistors in the sub-10 nm regime: A first-principles study”. Lu AKA, Pourtois G, Agarwal T, Afzalian A, Radu IP, Houssa M, Applied physics letters 108, 043504 (2016). http://doi.org/10.1063/1.4940685
Abstract: The impact of the scaling of the channel length on the performances of metal-oxide-semiconductor field effect transistors, based on two-dimensional (2D) channel materials, is theoretically investigated, using density functional theory combined with the non-equilibrium Green's function method. It is found that the scaling of the channel length below 10nm leads to strong device performance degradations. Our simulations reveal that this degradation is essentially due to the tunneling current flowing between the source and the drain in these aggressively scaled devices. It is shown that this electron tunneling process is modulated by the effective mass of the 2D channel material, and sets the limit of the scaling in future transistor designs. (C) 2016 AIP Publishing LLC.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.411
Times cited: 4
DOI: 10.1063/1.4940685
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