“Atomic Structure of Wurtzite CdSe (Core)/CdS (Giant Shell) Nanobullets Related to Epitaxy and Growth”. Bladt E, van Dijk-Moes RJA, Peters J, Montanarella F, de Mello Donega C, Vanmaekelbergh D, Bals S, Journal of the American Chemical Society 138, 14288 (2016). http://doi.org/10.1021/jacs.6b06443
Abstract: Hetero-nanocrystals consisting of a CdSe core and a giant CdS shell have shown remarkable optical properties which are promising for applications in opto-electrical devices. Since these properties sensitively depend on the size and shape, a morphological characterization is of high interest. Here, we present a High Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM) study of CdSe (core) / CdS (giant shell) hetero-nanocrystals. Electron tomography reveals that the nanocrystals have a bullet shape, either ending in a tip or a small dip, and that the CdSe core is positioned closer to the tip (or dip) than to the hexagonal base. Based on a high resolution HAADF-STEM study, we were able to determine all the surface facets. We present a heuristic model for the different growth stages of the CdS crystal around the CdSe core.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 13.858
Times cited: 28
DOI: 10.1021/jacs.6b06443
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“Highly Luminescent Cesium Lead Halide Perovskite Nanocrystals with Tunable Composition and Thickness by Ultrasonication”. Tong Y, Bladt E, Aygüler MF, Manzi A, Milowska KZ, Hintermayr VA, Docampo P, Bals S, Urban AS, Polavarapu L, Feldmann J, Angewandte Chemie: international edition in English 55, 13887 (2016). http://doi.org/10.1002/anie.201605909
Abstract: We describe the simple, scalable, single-step, and polar-solvent-free synthesis of high-quality colloidal CsPbX3 (X=Cl, Br, and I) perovskite nanocrystals (NCs) with tunable halide ion composition and thickness by direct ultrasonication of the corresponding precursor solutions in the presence of organic capping molecules. High angle annular dark field scanning transmission electron microscopy (HAADF-STEM) revealed the cubic crystal structure and surface termination of the NCs with atomic resolution. The NCs exhibit high photoluminescence quantum yields, narrow emission line widths, and considerable air stability. Furthermore, we investigated the quantum size effects in CsPbBr3 and CsPbI3 nanoplatelets by tuning their thickness down to only three to six monolayers. The high quality of the prepared NCs (CsPbBr3) was confirmed by amplified spontaneous emission with low thresholds. The versatility of this synthesis approach was demonstrated by synthesizing different perovskite NCs.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 11.994
Times cited: 549
DOI: 10.1002/anie.201605909
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“Detecting and locating light atoms from high-resolution STEM images: The quest for a single optimal design”. Gonnissen J, De Backer A, den Dekker AJ, Sijbers J, Van Aert S, Ultramicroscopy 170, 128 (2016). http://doi.org/10.1016/j.ultramic.2016.07.014
Abstract: In the present paper, the optimal detector design is investigated for both detecting and locating light atoms from high resolution scanning transmission electron microscopy (HR STEM) images. The principles of detection theory are used to quantify the probability of error for the detection of light atoms from HR STEM images. To determine the optimal experiment design for locating light atoms, use is made of the so-called Cramer-Rao Lower Bound (CRLB). It is investigated if a single optimal design can be found for both the detection and location problem of light atoms. Furthermore, the incoming electron dose is optimised for both research goals and it is shown that picometre range precision is feasible for the estimation of the atom positions when using an appropriate incoming electron dose under the optimal detector settings to detect light atoms.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 2.843
Times cited: 6
DOI: 10.1016/j.ultramic.2016.07.014
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“Silicene nanoribbons on transition metal dichalcogenide substrates : effects on electronic structure and ballistic transport”. van den Broek B, Houssa M, Lu A, Pourtois G, Afanas'ev V, Stesmans A, Nano Research 9, 3394 (2016). http://doi.org/10.1007/S12274-016-1217-4
Abstract: The idea of stacking multiple monolayers of different two-dimensional materials has become a global pursuit. In this work, a silicene armchair nanoribbon of width W and van der Waals-bonded to different transition-metal dichalcogenide (TMD) bilayer substrates MoX2 and WX2, where X = S, Se, Te is considered. The orbital resolved electronic structure and ballistic transport properties of these systems are simulated by employing van der Waals-corrected density functional theory and nonequilibrium Green's functions. We find that the lattice mismatch with the underlying substrate determines the electronic structure, correlated with the silicene buckling distortion and ultimately with the contact resistance of the two-terminal system. The smallest lattice mismatch, obtained with the MoTe2 substrate, results in the silicene ribbon properties coming close to those of a freestanding one. With the TMD bilayer acting as a dielectric layer, the electronic structure is tunable from a direct to an indirect semiconducting layer, and subsequently to a metallic electronic dispersion layer, with a moderate applied perpendicular electric field.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.354
Times cited: 2
DOI: 10.1007/S12274-016-1217-4
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“Mg(OH)2-WS2 van der Waals heterobilayer : electric field tunable band-gap crossover”. Yagmurcukardes M, Torun E, Senger RT, Peeters FM, Sahin H, Physical review B 94, 195403 (2016). http://doi.org/10.1103/PHYSREVB.94.195403
Abstract: Magnesium hydroxide [Mg(OH)(2)] has a layered brucitelike structure in its bulk form and was recently isolated as a new member of two-dimensional monolayer materials. We investigated the electronic and optical properties of monolayer crystals of Mg(OH)(2) and WS2 and their possible heterobilayer structure by means of first-principles calculations. It was found that both monolayers of Mg(OH)(2) and WS2 are direct-gap semiconductors and these two monolayers form a typical van der Waals heterostructure with a weak interlayer interaction and a type-II band alignment with a staggered gap that spatially separates electrons and holes. We also showed that an out-of-plane electric field induces a transition from a staggered to a straddling-type heterojunction. Moreover, by solving the Bethe-Salpeter equation on top of single-shot G(0)W(0) calculations, we show that the low-energy spectrum of the heterobilayer is dominated by the intralyer excitons of the WS2 monolayer. Because of the staggered interfacial gap and the field-tunable energy-band structure, the Mg(OH)(2)-WS2 heterobilayer can become an important candidate for various optoelectronic device applications in nanoscale.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 38
DOI: 10.1103/PHYSREVB.94.195403
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“A robust nitrifying community in a bioreactor at 50 degrees C opens up the path for thermophilic nitrogen removal”. Courtens ENP, Spieck E, Vilchez-Vargas R, Bode S, Boeckx P, Schouten S, Jauregui R, Pieper DH, Vlaeminck SE, Boon N, The ISME journal : multidisciplinary journal of microbial ecology 10, 2293 (2016). http://doi.org/10.1038/ISMEJ.2016.8
Abstract: The increasing production of nitrogen-containing fertilizers is crucial to meet the global food demand, yet high losses of reactive nitrogen associated with the food production/consumption chain progressively deteriorate the natural environment. Currently, mesophilic nitrogen-removing microbes eliminate nitrogen from wastewaters. Although thermophilic nitrifiers have been separately enriched from natural environments, no bioreactors are described that couple these processes for the treatment of nitrogen in hot wastewaters. Samples from composting facilities were used as inoculum for the batch-wise enrichment of thermophilic nitrifiers (350 days). Subsequently, the enrichments were transferred to a bioreactor to obtain a stable, high-rate nitrifying process (560 days). The community contained up to 17% ammonia-oxidizing archaea (AOAs) closely related to 'Candidatus Nitrososphaera gargensis', and 25% nitrite-oxidizing bacteria (NOBs) related to Nitrospira calida. Incorporation of C-13-derived bicarbonate into the respective characteristic membrane lipids during nitrification supported their activity as autotrophs. Specific activities up to 198 +/- 10 and 894 +/- 81 mg N g(-1) VSS per day for AOAs and NOBs were measured, where NOBs were 33% more sensitive to free ammonia. The NOBs were extremely sensitive to free nitrous acid, whereas the AOAs could only be inhibited by high nitrite concentrations, independent of the free nitrous acid concentration. The observed difference in product/substrate inhibition could facilitate the development of NOB inhibition strategies to achieve more cost-effective processes such as deammonification. This study describes the enrichment of autotrophic thermophilic nitrifiers from a nutrient-rich environment and the successful operation of a thermophilic nitrifying bioreactor for the first time, facilitating opportunities for thermophilic nitrogen removal biotechnology.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1038/ISMEJ.2016.8
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“Superconducting YBa2Cu3O7-δNanocomposites Using Preformed ZrO2Nanocrystals: Growth Mechanisms and Vortex Pinning Properties”. De Keukeleere K, Cayado P, Meledin A, Vallès F, De Roo J, Rijckaert H, Pollefeyt G, Bruneel E, Palau A, Coll M, Ricart S, Van Tendeloo G, Puig T, Obradors X, Van Driessche I, Advanced Electronic Materials 2, 1600161 (2016). http://doi.org/10.1002/aelm.201600161
Abstract: Although high temperature superconductors are promising for power applications, the production of low-cost coated conductors with high current densities—at high magnetic fields—remains challenging. A superior superconducting YBa2Cu3O7–δ nanocomposite is fabricated via chemical solution deposition (CSD) using preformed nanocrystals (NCs). Preformed, colloidally stable ZrO2 NCs are added to the trifluoroacetic acid based precursor solution and the NCs' stability is confirmed up to 50 mol% for at least 2.5 months. These NCs tend to disrupt the epitaxial growth of YBa2Cu3O7–δ, unless a thin seed layer is applied. A 10 mol% ZrO2 NC addition proved to be optimal, yielding a critical current density JC of 5 MA cm−2 at 77 K in self-field. Importantly, this new approach results in a smaller magnetic field decay of JC(H//c) for the nanocomposite compared to a pristine film. Furthermore, microstructural analysis of the YBa2Cu3O7–δ nanocomposite films reveals that different strain generation mechanisms may occur compared to the spontaneous segregation approach. Yet, the generated nanostrain in the YBa2Cu3O7–δ nanocomposite results in an improvement of the superconducting properties similar to the spontaneous segregation approach. This new approach, using preformed NCs in CSD coatings, can be of great potential for high magnetic field applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Times cited: 26
DOI: 10.1002/aelm.201600161
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“CO2 conversion in a gliding arc plasma: 1D cylindrical discharge model”. Wang W, Berthelot A, Kolev S, Tu X, Bogaerts A, Plasma sources science and technology 25, 065012 (2016). http://doi.org/10.1088/0963-0252/25/6/065012
Abstract: CO 2 conversion by a gliding arc plasma is gaining increasing interest, but the underlying mechanisms for an energy-efficient process are still far from understood. Indeed, the chemical complexity of the non-equilibrium plasma poses a challenge for plasma modeling due to the huge computational load. In this paper, a one-dimensional (1D) gliding arc model is developed in a cylindrical frame, with a detailed non-equilibrium CO 2 plasma chemistry set, including the CO 2 vibrational kinetics up to the dissociation limit. The model solves a set of time- dependent continuity equations based on the chemical reactions, as well as the electron energy balance equation, and it assumes quasi-neutrality in the plasma. The loss of plasma species and heat due to convection by the transverse gas flow is accounted for by using a characteristic frequency of convective cooling, which depends on the gliding arc radius, the relative velocity of the gas flow with respect to the arc and on the arc elongation rate. The calculated values for plasma density and plasma temperature within this work are comparable with experimental data on gliding arc plasma reactors in the literature. Our calculation results indicate that excitation to the vibrational levels promotes efficient dissociation in the gliding arc, and this is consistent with experimental investigations of the gliding arc based CO 2 conversion in the literature. Additionally, the dissociation of CO 2 through collisions with O atoms has the largest contribution to CO 2 splitting under the conditions studied. In addition to the above results, we also demonstrate that lumping the CO 2 vibrational states can bring a significant reduction of the computational load. The latter opens up the way for 2D or 3D models with an accurate description of the CO 2 vibrational kinetics.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.302
Times cited: 3
DOI: 10.1088/0963-0252/25/6/065012
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“Atomic Collapse in Graphene”. Moldovan D, Peeters FM, Nanomaterials For Security , 3 (2016). http://doi.org/10.1007/978-94-017-7593-9_1
Abstract: When the charge Z of an atom exceeds the critical value of 170, it will undergo a process called atomic collapse which triggers the spontaneous creation of electron-positron pairs. The high charge requirements have prevented the observation of this phenomenon with real atomic nuclei. However, thanks to the relativistic nature of the carriers in graphene, the same physics is accessible at a much lower scale. The atomic collapse analogue in graphene is realized using artificial nuclei which can be created via the deposition of impurities on the surface of graphene or using charged vacancies. These supercritically charged artificial nuclei trap electrons in a sequence of quasi-bound states which can be observed experimentally as resonances in the local density of states.
Keywords: P1 Proceeding; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Times cited: 3
DOI: 10.1007/978-94-017-7593-9_1
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“Jackson Pollock's Number 1A, 1948 : a non-invasive study using macro-x-ray fluorescence mapping (MA-XRF) and multivariate curve resolution-alternating least squares (MCR-ALS) analysis”. Martins A, Coddington J, van der Snickt G, van Driel B, McGlinchey C, Dahlberg D, Janssens K, Dik J, Heritage science 4, 33 (2016). http://doi.org/10.1186/S40494-016-0105-2
Abstract: Jackson Pollock's Number 1A, 1948 painting was investigated using in situ scanning macro-x-ray fluorescence mapping (MA-XRF) to help characterize the artist's materials and his creative process. A multivariate curve resolution-alternating least squares (MCR-ALS) approach was used to examine the hyperspectral data and obtain distribution maps and signature spectra for the paints he used. The composition of the paints was elucidated based on the chemical elements identified in the signature spectra and a tentative list of pigments, fillers and other additives is proposed for eleven different paints and for the canvas. The paint distribution maps were used to virtually reconstruct the artist process and document the sequence and manner in which Pollock applied the different paints, using deliberate and specific gestures.
Keywords: A1 Journal article; Art; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1186/S40494-016-0105-2
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“A combined 3D and 2D light scattering study on aqueous colloidal model systems with tunable interactions”. Liu Y, Claes N, Trepka B, Bals S, Lang PR, Soft matter 12, 8485 (2016). http://doi.org/10.1039/c6sm01376g
Abstract: In this article we report on the synthesis and characterization of a system of colloidal spheres suspended in an aqueous solvent which can be refractive index-matched, thus allowing for investigations of the particle near-wall dynamics by evanescent wave dynamic light scattering at concentrations up to the isotropic to ordered transition and beyond. The particles are synthesized by copolymerization of a fluorinated acrylic ester monomer with a polyethylene-glycol (PEG) oligomer by surfactant free emulsion polymerization. Static and dynamic light scattering experiments in combination with cryo transmission electron microscopy reveal that the particles have a core shell structure with a significant enrichment of the PEG chains on the particles surface. In index-matching DMSO/water suspensions the particles arrange in an ordered phase at volume fraction above 7%, if no additional electrolyte is present. The near-wall dynamics at low volume fraction are quantitatively described by the combination of electrostatic repulsion and hydrodynamic interaction between the particles and the wall. At volume fractions close to the isotropic to ordered transition, the near-wall dynamics are more complex and qualitatively reminiscent of the behaviour which was observed in hard sphere suspensions at high concentrations.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.889
Times cited: 2
DOI: 10.1039/c6sm01376g
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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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“Uncoupling the solids retention times of flocs and granules in mainstream deammonification : a screen as effective out-selection tool for nitrite oxidizing bacteria”. Han M, Vlaeminck SE, Al-Omari A, Wett B, Bott C, Murthy S, De Clippeleir H, Bioresource technology 221, 195 (2016). http://doi.org/10.1016/J.BIORTECH.2016.08.115
Abstract: This study focused on a physical separator in the form of a screen to out-select nitrite oxidizing bacteria (NOB) for mainstream sewage treatment. This separation relied on the principle that the NOB prefer to grow in flocs, while anammox bacteria (AnAOB) reside in granules. Two types of screens (vacuum and vibrating) were tested for separating these fractions. The vibrating screen was preferred due to more moderate normal forces and additional tangential forces, better balancing retention efficiency of AnAOB granules (41% of the AnAOB activity) and washout of NOB (92% activity washout). This operation resulted in increased NOB out-selection (AerAOB/NOB ratio of 2.3) and a total nitrogen removal efficiency of 70% at influent COD/N ratio of 1.4. An effluent total nitrogen concentration <10 mg N/L was achieved using this novel approach combining biological selection with physical separation, opening up the path towards energy positive sewage treatment. (C) 2016 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.BIORTECH.2016.08.115
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“Energy levels of ABC-stacked trilayer graphene quantum dots with infinite-mass boundary conditions”. Mirzakhani M, Zarenia M, da Costa DR, Ketabi SA, Peeters FM, Physical review B 94, 165423 (2016). http://doi.org/10.1103/PHYSREVB.94.165423
Abstract: Using the continuum model, we investigate the confined states and the corresponding wave functions of ABC-stacked trilayer graphene (TLG) quantum dots (QDs). First, a general infinite-mass boundary condition is derived and applied to calculate the electron and hole energy levels of a circular QD in both the absence and presence of a perpendicular magnetic field. Our analytical results for the energy spectra agree with those obtained by using the tight-binding model, where a TLG QD is surrounded by a staggered potential. Our findings show that (i) the energy spectrum exhibits intervalley symmetry E-K(e)(m) = -E-K'(h)(m) for the electron (e) and hole (h) states, where m is the angular momentum quantum number, (ii) the zero-energy Landau level (LL) is formed by the magnetic states with m <= 0 for both Dirac valleys, that is different from monolayer and bilayer graphene QD with infinite-mass potential in which only one of the cones contributes, and (iii) groups of three quantum Hall edge states in the tight-binding magnetic spectrum approach the zero LL, which results from the layer symmetry in TLG QDs.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 9
DOI: 10.1103/PHYSREVB.94.165423
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“Fe3O4@MIL-101-A selective and regenerable adsorbent for the removal of as species from water”. Folens K, Leus K, Nicomel NR, Meledina M, Turner S, Van Tendeloo G, Du Laing G, Van Der Voort P, European journal of inorganic chemistry 2016, 4395 (2016). http://doi.org/10.1002/EJIC.201600160
Abstract: The chromium-based metal organic framework MIL-101(Cr) served as a host for the in situ synthesis of Fe3O4 nano particles. This hybrid nanomaterial was tested as an adsorbent for arsenite and arsenate species in groundwater and surface water and showed excellent affinity towards As-III and As-V species. The adsorption capacities of 121.5 and 80.0 mg g(-1) for arsenite and arsenate species, respectively, are unprecedented. The presence of Ca2+, Mg2+, and phosphate ions and natural organic matter does not affect the removal efficiency or the selectivity. The structural integrity of the hybrid nanomaterial was maintained during the adsorption process and even after desorption through phosphate elution. Additionally, no significant leaching of Cr or Fe species was observed.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.444
Times cited: 27
DOI: 10.1002/EJIC.201600160
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“Controlled growth mechanism of poly (3-hexylthiophene) nanowires”. Kiymaz D, Yagmurcukardes M, Tomak A, Sahin H, Senger RT, Peeters FM, Zareie HM, Zafer C, Nanotechnology 27, 455604 (2016). http://doi.org/10.1088/0957-4484/27/45/455604
Abstract: Synthesis of 1D-polymer nanowires by a self-assembly method using marginal solvents is an attractive technique. While the formation mechanism is poorly understood, this method is essential in order to control the growth of nanowires. Here we visualized the time-dependent assembly of poly (3-hexyl-thiophene-2,5-diyl) (P3HT) nanowires by atomic force microscopy and scanning tunneling microscopy. The assembly of P3HT nanowires was carried out at room temperature by mixing cyclohexanone (CHN), as a poor solvent, with polymer solution in 1,2-dichlorobenzene (DCB). Both pi-pi stacking and planarization, obtained at the mix volume ratio of P3HT (in DCB):CHN (10:7), were considered during the investigation. We find that the length of nanowires was determined by the ordering of polymers in the polymer repetition direction. Additionally, our density functional theory calculations revealed that the presence of DCB and CHN molecules that stabilize the structural distortions due to tail group of polymers was essential for the core-wire formation.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 3.44
Times cited: 24
DOI: 10.1088/0957-4484/27/45/455604
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“Infrared to terahertz optical conductivity of n-type and p-type monolayer MoS2 in the presence of Rashba spin-orbit coupling”. Xiao YM, Xu W, Van Duppen B, Peeters FM, Physical review B 94, 155432 (2016). http://doi.org/10.1103/PHYSREVB.94.155432
Abstract: We investigate the effect of Rashba spin-orbit coupling (SOC) on the optoelectronic properties of n- and p-type monolayer MoS2. The optical conductivity is calculated within the Kubo formalism. We find that the spin-flip transitions enabled by the Rashba SOC result in a wide absorption window in the optical spectrum. Furthermore, we evaluate the effects of the polarization direction of the radiation, temperature, carrier density, and the strength of the Rashba spin-orbit parameter on the optical conductivity. We find that the position, width, and shape of the absorption peak or absorption window can be tuned by varying these parameters. This study shows that monolayer MoS2 can be a promising tunable optical and optoelectronic material that is active in the infrared to terahertz spectral range.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 20
DOI: 10.1103/PHYSREVB.94.155432
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“Farm household risk balancing : empirical evidence from Switzerland”. de Mey Y, Wauters E, Schmid D, Lips M, Vancauteren M, Van Passel S, European Review Of Agricultural Economics 43 (2016). http://doi.org/10.1093/ERAE/JBV030
Abstract: Empirical evidence on household risk balancing behaviour is presented by estimating a fixed effects seemingly unrelated regression model using Swiss Farm Accountancy Data Network data. We find that in response to changes in expected business risks, Swiss farm households not only make strategic farm financial risk decisions (original risk balancing), but also make strategic off-farm decisions (household risk balancing) by altering their share of off-farm income and relative consumption. Small farms appear to make more use of household risk balancing strategies whereas large farms conversely make more use of the original risk balancing strategy.
Keywords: A1 Journal article; Economics
Impact Factor: 1.6
Times cited: 15
DOI: 10.1093/ERAE/JBV030
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“TEM and AES investigations of the natural surface nano-oxide layer of an AISI 316L stainless steel microfibre”. Ramachandran D, Egoavil R, Crabbe A, Hauffman T, Abakumov A, Verbeeck J, Vandendael I, Terryn H, Schryvers D, Journal of microscopy 264, 207 (2016). http://doi.org/10.1111/jmi.12434
Abstract: The chemical composition, nanostructure and electronic structure of nanosized oxide scales naturally formed on the surface of AISI 316L stainless steel microfibres used for strengthening of composite materials have been characterised using a combination of scanning and transmission electron microscopy with energy-dispersive X-ray, electron energy loss and Auger spectroscopy. The analysis reveals the presence of three sublayers within the total surface oxide scale of 5.0-6.7 nm thick: an outer oxide layer rich in a mixture of FeO.Fe2 O3 , an intermediate layer rich in Cr2 O3 with a mixture of FeO.Fe2 O3 and an inner oxide layer rich in nickel.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.692
Times cited: 12
DOI: 10.1111/jmi.12434
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“Velocimetry of superconducting vortices based on stroboscopic resonances”. Jelić, ZL, Milošević, MV, Silhanek AV, Scientific reports 6, 35687 (2016). http://doi.org/10.1038/SREP35687
Abstract: An experimental determination of the mean vortex velocity in superconductors mostly relies on the measurement of flux-flow resistance with magnetic field, temperature, or driving current. In the present work we introduce a method combining conventional transport measurements and a frequency-tuned flashing pinning potential to obtain reliable estimates of the vortex velocity. The proposed device is characterized using the time-dependent Ginzburg-Landau formalism, where the velocimetry method exploits the resonances in mean vortex dissipation when temporal commensuration occurs between the vortex crossings and the flashing potential. We discuss the sensitivity of the proposed technique on applied current, temperature and heat diffusion, as well as the vortex core deformations during fast motion.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 4.259
Times cited: 22
DOI: 10.1038/SREP35687
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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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“Complex Microstructure and Magnetism in Polymorphic CaFeSeO”. Cassidy SJ, Batuk M, Batuk D, Hadermann J, Woodruff DN, Thompson AL, Clarke SJ, Inorganic chemistry 55, 10714 (2016). http://doi.org/10.1021/acs.inorgchem.6b01951
Abstract: The structural complexity of the antiferromagnetic oxide selenide CaFeSeO is described. The compound contains puckered FeSeO layers composed of FeSe2O2 tetrahedra sharing all their vertexes. Two polymorphs coexist that can be derived from an archetype BaZnSO structure by cooperative tilting of the FeSe2O2 tetrahedra. The polymorphs differ in the relative arrangement of the puckered layers of vertex-linked FeSe2O2 tetrahedra. In a noncentrosymmetric Cmc21 polymorph (a = 3.89684(2) A, b = 13.22054(8) A, c = 5.93625(2) A) the layers are related by the C-centering translation, while in a centrosymmetric Pmcn polymorph, with a similar cell metric (a = 3.89557(6) A, b = 13.2237(6) A, c = 5.9363(3) A), the layers are related by inversion. The compound shows long-range antiferromagnetic order below a Neel temperature of 159(1) K with both polymorphs showing antiferromagnetic coupling via Fe-O-Fe linkages and ferromagnetic coupling via Fe-Se-Fe linkages within the FeSeO layers. The magnetic susceptibility also shows evidence for weak ferromagnetism which is modeled in the refinements of the magnetic structure as arising from an uncompensated spin canting in the noncentrosymmetric polymorph. There is also a spin glass component to the magnetism which likely arises from the disordered regions of the structure evident in the transmission electron microscopy.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.857
Times cited: 6
DOI: 10.1021/acs.inorgchem.6b01951
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“Ba-3(Cr0.97(1)Te0.03(1))(2)TeO9: in Search of Jahn-Teller Distorted Cr(II) Oxide”. Li M-R, Deng Z, Lapidus SH, Stephens PW, Segre CU, Croft M, Sena RP, Hadermann J, Walker D, Greenblatt M, Inorganic chemistry 55, 10135 (2016). http://doi.org/10.1021/ACS.INORGCHEM.6B01047
Abstract: A novel 6H-type hexagonal perovskite Ba-3(Cr0.97(1)Te0.03(1))(2)TeO9 was prepared at high pressure (6 GPa) and temperature (1773 K). Both transmission electron microscopy and synchrotron powder X-ray diffraction data demonstrate that Ba-3(Cr0.97(1)Te0.03(1))(2)TeO9 crystallizes in P6(3)/mmc with face-shared (Cr0.97(1)Te0.03(1))O-6 octahedral pairs interconnected with TeO6 octahedra via corner-sharing. Structure analysis shows a mixed Cr2+/Cr3+ valence state with similar to 10% Cr2+. The existence of Cr2+ in Ba-3(Cr0.10(1)2+Cr0.87(1)3+Te0.036+)(2)TeO9 is further evidenced by X-ray absorption near-edge spectroscopy. Magnetic properties measurements show a paramagnetic response down to 4 K and a small glassy-state curvature at low temperature. In this work, the octahedral Cr2+O6 component is stabilized in an oxide material for the first time; the expected Jahn-Teller distortion of high-spin (d(4)) Cr2+ is not found, which is attributed to the small proportion of Cr2+ (similar to 10%) and the face-sharing arrangement of CrO6 octahedral pairs, which structurally disfavor axial distortion.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.857
Times cited: 2
DOI: 10.1021/ACS.INORGCHEM.6B01047
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“A geometrical model for testing bilateral symmetry of bamboo leaf with a simplified Gielis equation”. Lin S, Zhang L, Reddy GVP, Hui C, Gielis J, Ding Y, Shi P, Ecology and evolution 6, 6798 (2016). http://doi.org/10.1002/ECE3.2407
Abstract: The size and shape of plant leaves change with growth, and an accurate description of leaf shape is crucial for describing plant morphogenesis and development. Bilateral symmetry, which has been widely observed but poorly examined, occurs in both dicot and monocot leaves, including all nominated bamboo species (approximately 1,300 species), of which at least 500 are found in China. Although there are apparent differences in leaf size among bamboo species due to genetic and environmental profiles, bamboo leaves have bilateral symmetry with parallel venation and appear similar across species. Here, we investigate whether the shape of bamboo leaves can be accurately described by a simplified Gielis equation, which consists of only two parameters (leaf length and shape) and produces a perfect bilateral shape. To test the applicability of this equation and the occurrence of bilateral symmetry, we first measured the leaf length of 42 bamboo species, examining >500 leaves per species. We then scanned 30 leaves per species that had approximately the same length as the median leaf length for that species. The leaf-shape data from scanned profiles were fitted to the simplified Gielis equation. Results confirmed that the equation fits the leaf-shape data extremely well, with the coefficients of determination being 0.995 on average. We further demonstrated the bilateral symmetry of bamboo leaves, with a clearly defined leaf-shape parameter of all 42 bamboo species investigated ranging from 0.02 to 0.1. This results in a simple and reliable tool for precise determination of bamboo species, with applications in forestry, ecology, and taxonomy.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1002/ECE3.2407
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“Intrinsic magnetism in penta-hexa-graphene: A first-principles study”. Aierken Y, Leenaerts O, Peeters FM, Physical review B 94, 155410 (2016). http://doi.org/10.1103/PHYSREVB.94.155410
Abstract: Recently, several monolayer carbon allotropes have been proposed. The magnetic properties of these metal-free materials are investigated, and we explore a special type of all carbon system having an intrinsic magnetic ground state. The structure is composed of mixing pentagonal and hexagonal rings of carbon atoms, such that the unit cell consists of eleven atoms, where two C atoms each have an unpaired electron each with a local magnetic moment. The antiferromagnetic (AFM) state has a lower energy than the ferromagnetic (FM) one. However, a strain-driven transition to the FM ground state is possible. The application of strain not only lowers the energy of the FM state but it also induces an energy barrier of about 13 meV/(magnetic atom) to protect the FM state from excitation. Our findings based on first-principles calculations will motivate other works on similar metal-free magnetic monolayer materials and will have an impact on their possible applications in spintronic devices.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 13
DOI: 10.1103/PHYSREVB.94.155410
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“Anisotropic type-I superconductivity and anomalous superfluid density in OsB2”. Bekaert J, Vercauteren S, Aperis A, Komendová, L, Prozorov R, Partoens B, Milošević, MV, Physical review B 94, 144506 (2016). http://doi.org/10.1103/PhysRevB.94.144506
Abstract: We present a microscopic study of superconductivity in OsB2 , and discuss the origin and characteristic length
scales of the superconducting state. From first-principles we show that OsB2 is characterized by three different
Fermi sheets, and we prove that this fermiology complies with recent quantum-oscillation experiments. Using the
found microscopic properties, and experimental data from the literature, we employ Ginzburg-Landau relations
to reveal that OsB2 is a distinctly type-I superconductor with a very low Ginzburg-Landau parameter κ—a rare
property among compound materials. We show that the found coherence length and penetration depth corroborate
the measured thermodynamic critical field. Moreover, our calculation of the superconducting gap structure using
anisotropic Eliashberg theory and ab initio calculated electron-phonon interaction as input reveals a single but
anisotropic gap. The calculated gap spectrum is shown to give an excellent account for the unconventional
behavior of the superfluid density of OsB2 measured in experiments as a function of temperature. This reveals
that gap anisotropy can explain such behavior, observed in several compounds, which was previously attributed
solely to a two-gap nature of superconductivity.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 19
DOI: 10.1103/PhysRevB.94.144506
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“Effective ionisation coefficients and critical breakdown electric field of CO2at elevated temperature: effect of excited states and ion kinetics”. Wang W, Bogaerts A, Plasma sources science and technology 25, 055025 (2016). http://doi.org/10.1088/0963-0252/25/5/055025
Abstract: Electrical breakdown by the application of an electric field occurs more easily in hot gases than in cold gases because of the extra electron-species interactions that occur as a result of dissociation, ionization and excitation at higher temperature. This paper discusses some overlooked physics and clarifies inaccuracies in the evaluation of the effective ionization coefficients and the critical reduced breakdown electric field of CO2 at elevated temperature, considering the influence of excited states and ion kinetics. The critical reduced breakdown electric field is obtained by balancing electron generation and loss mechanisms using the electron energy distribution function (EEDF) derived from the Boltzmann transport equation under the two-term approximation. The equilibrium compositions of the hot gas mixtures are determined based on Gibbs free energy minimization considering the ground states as well as vibrationally and electronically excited states as independent species, which follow a Boltzmann distribution with a fixed excitation temperature. The interaction cross sections between electrons and the excited species, not reported previously, are properly taken into account. Furthermore, the ion kinetics, including electron–ion recombination, associative electron detachment, charge transfer and ion conversion into stable negative ion clusters, are also considered. Our results indicate that the excited species lead to a greater population of high-energy electrons at higher gas temperature and this affects the Townsend rate coefficients (i.e. of electron impact ionization and attachment), but the critical reduced breakdown electric field strength of CO2 is only affected when also properly accounting for the ion kinetics. Indeed, the latter greatly influences the effective ionization coefficients and hence the critical reduced breakdown electric field at temperatures above 1500 K. The rapid increase of the dissociative electron attachment cross-section of molecular oxygen with rising vibrational quantum number leads to a larger electron loss rate and this enhances the critical reduced breakdown electric field strength in the temperature range where the concentration of molecular oxygen is relatively high. The results obtained in this work show reasonable agreement with experimental results from literature, and are important for the evaluation of the dielectric strength of CO2 in a highly reactive environment at elevated temperature.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.302
Times cited: 3
DOI: 10.1088/0963-0252/25/5/055025
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“Influence of defect distribution on the reducibility of CeO2-x nanoparticles”. Spadaro MC, Luches P, Bertoni G, Grillo V, Turner S, Van Tendeloo G, Valeri S, D'Addato S, Nanotechnology 27, 425705 (2016). http://doi.org/10.1088/0957-4484/27/42/425705
Abstract: Ceria nanoparticles (NPs) are fundamental in heterogeneous catalysis because of their ability to store or release oxygen depending on the ambient conditions. Their oxygen storage capacity is strictly related to the exposed planes, crystallinity, density and distribution of defects. In this work a study of ceria NPs produced with a ligand-free, physical synthesis method is presented. The NP films were grown by a magnetron sputtering based gas aggregation source and studied by high resolution- and scanning-transmission electron microscopy and x-ray photoelectron spectroscopy. In particular, the influence of the oxidation procedure on the NP reducibility has been investigated. The different reducibility has been correlated to the exposed planes, crystallinity and density and distribution of structural defects. The results obtained in this work represent a basis to obtain cerium oxide NP with desired oxygen transport properties.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.44
Times cited: 11
DOI: 10.1088/0957-4484/27/42/425705
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“Bending Gold Nanorods with Light”. Babynina A, Fedoruk M, Kuhler P, Meledin A, Doblinger M, Lohmueller T, Nano letters 16, 6485 (2016). http://doi.org/10.1021/acs.nanolett.6b03029
Abstract: V-shaped gold nanoantennas are the functional components of plasmonic metasurfaces, which are capable of manipulating light in unprecedented ways. Designing a metasurface requires the custom arrangement of individual antennas with controlled shape and orientation. Here, we show how highly crystalline gold nanorods in solution can be bend, one-by one, into a V-shaped geometry and printed to the surface of a solid support through a combination of plasmonic heating and optical force. Significantly, we demonstrate that both the bending angle and the orientation of each rod-antenna can be adjusted independent from each other by tuning the laser intensity and polarization. This approach is applicable for the patterning of V-shaped plasmonic antennas on almost any substrate, which holds great potential for the fabrication of ultrathin optical components and devices.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 12.712
Times cited: 24
DOI: 10.1021/acs.nanolett.6b03029
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“Hierarchical hexagonal boron nitride nanowall-diamond nanorod heterostructures with enhanced optoelectronic performance”. Sankaran KJ, Duc Quang Hoang, Korneychuk S, Kunuku S, Thomas JP, Pobedinskas P, Drijkoningen S, Van Bael MK, D'Haen J, Verbeeck J, Leou K-C, Leung KT, Lin I-N, Haenen K, RSC advances 6, 90338 (2016). http://doi.org/10.1039/C6RA19596B
Abstract: A superior field electron emission (FEE) source made from a hierarchical heterostructure, where two-dimensional hexagonal boron nitride (hBN) nanowalls were coated on one-dimensional diamond nanorods (DNRs), is fabricated using a simple and scalable method. FEE characteristics of hBN-DNR display a low turn-on field of 6.0 V mu m(-1), a high field enhancement factor of 5870 and a high life-time stability of 435 min. Such an enhancement in the FEE properties of hBN-DNR derives from the distinctive material combination, i.e., high aspect ratio of the heterostructure, good electron transport from the DNR to the hBN nanowalls and efficient field emission of electrons from the hBN nanowalls. The prospective application of these heterostructures is further evidenced by enhanced microplasma devices using hBN-DNR as a cathode, in which the threshold voltage was lowered to 350 V, affirming the role of hBN-DNR in the improvement of electron emission.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.108
Times cited: 8
DOI: 10.1039/C6RA19596B
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