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“Interplay of interfacial layers and blend composition to reduce thermal degradation of polymer solar cells at high temperature”. Ben Dkhil S, Pfannmöller M, Schroeder RR, Alkarsifi R, Gaceur M, Koentges W, Heidari H, Bals S, Margeat O, Ackermann J, Videlot-Ackermann C, ACS applied materials and interfaces 10, 3874 (2018). http://doi.org/10.1021/ACSAMI.7B17021
Abstract: The thermal stability of printed polymer solar cells at elevated temperatures needs to be improved to achieve high-throughput fabrication including annealing steps as well as long-term stability. During device processing, thermal annealing impacts both the organic photoactive layer, and the two interfacial layers make detailed studies of degradation mechanism delicate. A recently identified thermally stable poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b'-dithiopherie-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl) carbonyl] thieno [3,4-b]thiophenediyl]] : [6,6]-phenyl- C-71-butyric acid methyl ester (PTB7:PC70BM) blend as photoactive layer in combination with poly(3,4-ethylenedioxythiophene) polystyrene sulfonate as hole extraction layer is used here to focus on the impact of electron extraction layer (EEL) on the thermal stability of solar cells. Solar cells processed with densely packed ZnO nanoparticle layers still show 92% of the initial efficiency after constant annealing during 1 day at 140 degrees C, whereas partially covering ZnO layers as well as an evaporated calcium layer leads to performance losses of up to 30%. This demonstrates that the nature and morphology of EELs highly influence the thermal stability of the device. We extend our study to thermally unstable PTB7:[6,6]-phenyl-C-61-butyric acid methyl ester (PC60BM) blends to highlight the impact of ZnO on the device degradation during annealing. Importantly, only 12% loss in photocurrent density is observed after annealing at 140 degrees C during 1 day when using closely packed ZnO. This is in stark contrast to literature and addressed here to the use of a stable double-sided confinement during thermal annealing. The underlying mechanism of the inhibition of photocurrent losses is revealed by electron microscopy imaging and spatially resolved spectroscopy. We found that the double-sided confinement suppresses extensive fullerene diffusion during the annealing step, but with still an increase in size and distance of the enriched donor and acceptor domains inside the photoactive layer by an average factor of 5. The later result in combination with comparably small photocurrent density losses indicates the existence of an efficient transport of minority charge carriers inside the donor and acceptor enriched phases in PTB7:PC60BM blends.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 7.504
Times cited: 9
DOI: 10.1021/ACSAMI.7B17021
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“Tuning Size and Seed Position in Small Silver Nanorods”. Sánchez-Iglesias A, Zhuo X, Albrecht W, Bals S, Liz-Marzán LM, ACS materials letters 2, 1246 (2020). http://doi.org/10.1021/acsmaterialslett.0c00388
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 9
DOI: 10.1021/acsmaterialslett.0c00388
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“Effect of interface evolution on thermal conductivity of vacuum hot pressed SiC/Al composites”. Chen Z, Tan Z, Ji G, Schryvers D, Ouyang Q, Li Z, Advanced engineering materials 17, 1076 (2015). http://doi.org/10.1002/adem.201400412
Abstract: The SiC/Al composites have been fabricated by a vacuum hot pressing (VHP) process in order to study the effect of interface evolution on the global thermal conductivity (TC). By optimizing the VHP parameters of sintering temperature and time, the three different kinds of SiC/Al interface configurations, that is, non-bonded, diffusion-bonded, and reaction-bonded interfaces, are formed and identified by measurement of relative density, X-ray diffraction, scanning and (high-resolution) transmission electron microscopy. The VHPed composite sintered at 655 °C for 60 min is fully dense and presents a tightly-adhered and clean SiC/Al interface at the nanoscale, the ideal diffusion-bonded interface being the most favorable for minimizing interfacial thermal resistance, which in turn results in the highest TC of around 270 W/mK.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.319
Times cited: 9
DOI: 10.1002/adem.201400412
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“Ion Clouds in the Inductively Coupled Plasma Torch: A Closer Look through Computations”. Aghaei M, Lindner H, Bogaerts A, Analytical chemistry 88, 8005 (2016). http://doi.org/10.1021/acs.analchem.6b01189
Abstract: We have computationally investigated the introduction of copper elemental particles in an inductively coupled plasma torch connected to a sampling cone, including for the first time the ionization of the sample. The sample is inserted as liquid particles, which are followed inside the entire torch, i.e., from the injector inlet up to the ionization and reaching the sampler. The spatial position of the ion clouds inside the torch as well as detailed information on the copper species fluxes at the position of the sampler orifice and the exhausts of the torch are provided. The effect of on- and off-axis injection is studied. We clearly show that the ion clouds of on-axis injected material are located closer to the sampler with less radial diffusion. This guarantees a higher transport efficiency through the sampler cone. Moreover, our model reveals the optimum ranges of applied power and flow rates, which ensure the proper position of ion clouds inside the torch, i.e., close enough to the sampler to increase the fraction that can enter the mass spectrometer and with minimum loss of material toward the exhausts as well as a sufficiently high plasma temperature for efficient ionization.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 6.32
Times cited: 9
DOI: 10.1021/acs.analchem.6b01189
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“Unraveling the reactivity of minium towards bicarbonate and the role of lead oxides therein”. Ayalew E, Janssens K, De Wael K, Analytical chemistry 88, 1564 (2016). http://doi.org/10.1021/ACS.ANALCHEM.5B02503
Abstract: Understanding the reactivity of (semiconductor) pigments provides vital information on how to improve conservation strategies for works of art in order to avoid rapid degradation of the pigments. This study focuses on the photoactivity of minium (Pb3O4), a semiconductor pigment, that gives rise to strong discoloration phenomena upon exposure to various environmental conditions. To demonstrate its photoactivity, an electrochemical setup with minium-modified graphite electrode (C|Pb3O4) was used. It is confirmed that minium is a p-type semiconductor which is photoactive during illumination and becomes inactive in the dark. Raman measurements confirm the formation of the degradation products. The photoactivity of a semiconductor pigment is partly defined by the presence of lead oxide (PbO) impurities; these introduce new states in the original band gap. It will be experi-mentally evidenced that the presence of PbO particles in minium leads to an upward shift of the valence band that reduces the band gap. Thus, upon photoexcitation, the electron/hole separation is more easily initialized. The PbO/Pb3O4 composite electrodes demonstrate a higher reductive photocurrent compared to the photocurrent registered at pure PbO or Pb3O4 modified electrodes. Upon exposure to light with energy close to and above the band gap, electrons are excited from the valence band to the conduction band to initialize the reduction of Pb(IV) to Pb(II), resulting in the initial formation of PbO. However in the presence of bicarbonate ions, a significantly higher photoreduction current is recorded since the PbO reacts further to form hydrocerussite. Therefore the presence of bicarbonates in the environment stimulates the photodecomposition process of minium and plays an important role in the degradation process.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 6.32
Times cited: 9
DOI: 10.1021/ACS.ANALCHEM.5B02503
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“The corrosion process of sterling silver exposed to a Na2S solution: monitoring and characterizing the complex surface evolution using a multi-analytical approach”. Schalm O, Crabbé, A, Storme P, Wiesinger R, Gambirasi A, Grieten E, Tack P, Bauters S, Kleber C, Favaro M, Schryvers D, Vincze L, Terryn H, Patelli A, Applied Physics A-Materials Science &, Processing 122, 903 (2016). http://doi.org/10.1007/s00339-016-0436-6
Abstract: Many historical ‘silver’ objects are composed of sterling silver, a silver alloy containing small amounts of copper. Besides the dramatic impact of copper on the corrosion process, the chemical composition of the corrosion layer evolves continuously. The evolution of the surface during the exposure to a Na2S solution was monitored by means of visual observation at macroscopic level, chemical analysis at microscopic level and analysis at the nanoscopic level. The corrosion process starts with the preferential oxidation of copper, forming mixtures of oxides and sulphides while voids are being created beneath the corrosion layer. Only at a later stage, the silver below the corrosion layer is consumed. This results in the formation of jalpaite and at a later stage of acanthite. The acanthite is found inside the corrosion layer at the boundaries of jalpaite grains and as individual grains between the jalpaite grains but also as a thin film on top of the corrosion layer. The corrosion process could be described as a sequence of 5 subsequent surface states with transitions between these states.
Keywords: A1 Journal article; Electron Microscopy for Materials Science (EMAT);
Impact Factor: 1.455
Times cited: 9
DOI: 10.1007/s00339-016-0436-6
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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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“Quantitative Landau potentials for the martensitic transformation in Ni-Al”. Salje EKH, Zhang H, Schryvers D, Bartova B, Applied physics letters 90, 221903 (2007). http://doi.org/10.1063/1.2743927
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.411
Times cited: 9
DOI: 10.1063/1.2743927
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“On the manifestation of phosphorus-vacancy complexes in epitaxial Si:P films”. Dhayalan SK, Kujala J, Slotte J, Pourtois G, Simoen E, Rosseel E, Hikavyy A, Shimura Y, Iacovo S, Stesmans A, Loo R, Vandervorst W;, Applied physics letters 108, 082106 (2016). http://doi.org/10.1063/1.4942605
Abstract: In situ doped epitaxial Si: P films with P concentrations > 1 x 10(21) at./cm(3) are suitable for source-drain stressors of n-FinFETs. These films combine the advantages of high conductivity derived from the high P doping with the creation of tensile strain in the Si channel. It has been suggested that the tensile strain developed in the Si: P films is due to the presence of local Si3P4 clusters, which however do not contribute to the electrical conductivity. During laser annealing, the Si3P4 clusters are expected to disperse resulting in an increased conductivity while the strain reduces slightly. However, the existence of Si3P4 is not proven. Based on first-principles simulations, we demonstrate that the formation of vacancy centered Si3P4 clusters, in the form of four P atoms bonded to a Si vacancy, is thermodynamically favorable at such high P concentrations. We suggest that during post epi-growth annealing, a fraction of the P atoms from these clusters are activated, while the remaining part goes into interstitial sites, thereby reducing strain. We corroborate our conjecture experimentally using positron annihilation spectroscopy, electron spin resonance, and Rutherford backscattering ion channeling studies. (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: 9
DOI: 10.1063/1.4942605
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“Graphene quantum blisters : a tunable system to confine charge carriers”. Abdullah HM, Van der Donck M, Bahlouli H, Peeters FM, Van Duppen B, Applied physics letters 112, 213101 (2018). http://doi.org/10.1063/1.5023896
Abstract: Due to Klein tunneling, electrostatic confinement of electrons in graphene is not possible. This hinders the use of graphene for quantum dot applications. Only through quasi-bound states with finite lifetime has one achieved to confine charge carriers. Here, we propose that bilayer graphene with a local region of decoupled graphene layers is able to generate bound states under the application of an electrostatic gate. The discrete energy levels in such a quantum blister correspond to localized electron and hole states in the top and bottom layers. We find that this layer localization and the energy spectrum itself are tunable by a global electrostatic gate and that the latter also coincides with the electronic modes in a graphene disk. Curiously, states with energy close to the continuum exist primarily in the classically forbidden region outside the domain defining the blister. The results are robust against variations in size and shape of the blister which shows that it is a versatile system to achieve tunable electrostatic confinement in graphene. Published by AIP Publishing.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 9
DOI: 10.1063/1.5023896
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“Overcoming contrast reversals in focused probe ptychography of thick materials: An optimal pipeline for efficiently determining local atomic structure in materials science”. Gao C, Hofer C, Jannis D, Béché, A, Verbeeck J, Pennycook TJ, Applied physics letters 121, 081906 (2022). http://doi.org/10.1063/5.0101895
Abstract: Ptychography provides highly efficient imaging in scanning transmission electron microscopy (STEM), but questions have remained over its applicability to strongly scattering samples such as those most commonly seen in materials science. Although contrast reversals can appear in ptychographic phase images as the projected potentials of the sample increase, we show here how these can be easily overcome by a small amount of defocus. The amount of defocus is small enough that it not only can exist naturally when focusing using the annular dark field (ADF) signal but can also be adjusted post acquisition. The ptychographic images of strongly scattering materials are clearer at finite doses than other STEM techniques and can better reveal light atomic columns within heavy lattices. In addition, data for ptychography can now be collected simultaneously with the fastest of ADF scans. This combination of sensitivity and interpretability presents an ideal workflow for materials science.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4
Times cited: 9
DOI: 10.1063/5.0101895
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“Coincidence Detection of EELS and EDX Spectral Events in the Electron Microscope”. Jannis D, Müller-Caspary K, Béché, A, Verbeeck J, Applied Sciences-Basel 11, 9058 (2021). http://doi.org/10.3390/app11199058
Abstract: Recent advances in the development of electron and X-ray detectors have opened up the possibility to detect single events from which its time of arrival can be determined with nanosecond resolution. This allows observing time correlations between electrons and X-rays in the transmission electron microscope. In this work, a novel setup is described which measures individual events using a silicon drift detector and digital pulse processor for the X-rays and a Timepix3 detector for the electrons. This setup enables recording time correlation between both event streams while at the same time preserving the complete conventional electron energy loss (EELS) and energy dispersive X-ray (EDX) signal. We show that the added coincidence information improves the sensitivity for detecting trace elements in a matrix as compared to conventional EELS and EDX. Furthermore, the method allows the determination of the collection efficiencies without the use of a reference sample and can subtract the background signal for EELS and EDX without any prior knowledge of the background shape and without pre-edge fitting region. We discuss limitations in time resolution arising due to specificities of the silicon drift detector and discuss ways to further improve this aspect.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.679
Times cited: 9
DOI: 10.3390/app11199058
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“Electron microscopy characterisation of erbium silicide-thin films grown on a Si(111) substrate”. Frangis N, Van Tendeloo G, van Landuyt J, Muret P, Nguyen TTA, Applied surface science 102, 163 (1996). http://doi.org/10.1016/0169-4332(96)00040-2
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.711
Times cited: 9
DOI: 10.1016/0169-4332(96)00040-2
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“Empirical evaluation of metal deposition for the analysis of organic compounds with static secondary ion mass spectrometry (S-SIMS)”. de Mondt R, Adriaensen L, Vangaever F, Lenaerts J, van Vaeck L, Gijbels R, Applied surface science 252, 6652 (2006). http://doi.org/10.1016/j.apsusc.2006.02.110
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.387
Times cited: 9
DOI: 10.1016/j.apsusc.2006.02.110
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“Critical assessments and thermodynamic modeling of BaO-SiO2 and SiO2-TiO2 systems and their extensions into liquid immiscibility in the BaO-SiO2-TiO2 system”. Boulay E, Nakano J, Turner S, Idrissi H, Schryvers D, Godet S, Calphad computer coupling of phase diagrams and thermochemistry 47, 68 (2014). http://doi.org/10.1016/j.calphad.2014.06.004
Abstract: This study discusses rational reproduction of liquid immiscibility in the BaO-SiO2-TiO2 system. While a ternary assessment requires sub-binary descriptions in the same thermodynamic model, the related sub-binary systems BaO-SiO2, BaO-TiO2 and SiO2-TiO2 liquid and solid phases have been evaluated using different thermodynamic models in the literature. In this study, BaO-SiO2 and SiO2-TiO2 were assessed using the Ionic Two Sublattice model (I2SL) based on experimental data from the literature. BaO-TiO2 was already assessed using this model. Binary descriptions developed were then used for the assessment of liquid immiscibility in the BaO-SiO2-TiO2 system. Ternary interaction parameters were found necessary for rational reproduction of the new ternary experimental data gathered in the present work. The model parameters for each system were evaluated using a CAPLHAD approach. A set of parameters is proposed. They show good agreement between the calculated and experimental equilibrium liquidus, liquid immiscibility and thermochemical properties in the BaO-SiO2-TiO2 system. (C) 2014 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.6
Times cited: 9
DOI: 10.1016/j.calphad.2014.06.004
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“Influence of Cell Type and Culture Medium on Determining Cancer Selectivity of Cold Atmospheric Plasma Treatment”. Biscop, Lin, Boxem, Loenhout, Backer, Deben, Dewilde, Smits, Bogaerts, Cancers 11, 1287 (2019). http://doi.org/10.3390/cancers11091287
Abstract: Increasing the selectivity of cancer treatments is attractive, as it has the potential to reduce side-effects of therapy. Cold atmospheric plasma (CAP) is a novel cancer treatment that disrupts the intracellular oxidative balance. Several reports claim CAP treatment to be selective, but retrospective analysis of these studies revealed discrepancies in several biological factors and culturing methods. Before CAP can be conclusively stated as a selective cancer treatment, the importance of these factors must be investigated. In this study, we evaluated the influence of the cell type, cancer type, and cell culture medium on direct and indirect CAP treatment. Comparison of cancerous cells with their non-cancerous counterparts was performed under standardized conditions to determine selectivity of treatment. Analysis of seven human cell lines (cancerous: A549, U87, A375, and Malme-3M; non-cancerous: BEAS-2B, HA, and HEMa) and five different cell culture media (DMEM, RPMI1640, AM, BEGM, and DCBM) revealed that the tested parameters strongly influence indirect CAP treatment, while direct treatment was less affected. Taken together, the results of our study demonstrate that cell type, cancer type, and culturing medium must be taken into account before selectivity of CAP treatment can be claimed and overlooking these parameters can easily result in inaccurate conclusions of selectivity.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); Center for Oncological Research (CORE)
Times cited: 9
DOI: 10.3390/cancers11091287
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“Fabrication of perovskite capillary membranes for high temperature gas separation”. Van Noyen J, Middelkoop V, Buysse C, Kovalevsky A, Snijkers F, Buekenhoudt A, Mullens S, Luyten J, Kretzschmar J, Lenaerts S, Catalysis today 193, 172 (2012). http://doi.org/10.1016/J.CATTOD.2012.03.005
Abstract: Oxygen-permeable perovskites with mixed ionic-electronic conducting properties can play an important role in carbon capture and storage techniques. Their ability to separate oxygen from air is needed, more specifically, in oxy-fuel and pre-combustion technologies. In this work, the first detailed comparative analysis and new results are reported on four types of Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) capillary membranes: non-coated sulphur-containing; catalyst-coated sulphur-containing; non-coated sulphur-free and catalyst-coated sulphur-free. The fabrication of BSCF capillaries by a spinning technique based on phase inversion is further discussed and their oxygen separation performances are interpreted. The comparison of the performance of these different generations of BSCF capillaries of similar dimensions demonstrates a significant impact of the sulphur contamination on both the oxygen flux through the membrane and the activation energy of the overall oxygen transport mechanism. Careful attention is paid to the effect of activation layers on both sulphur-free and sulphur-containing types of capillaries. Additional long-term testing of the sulphur-free BSCF capillaries is presented, where partial decomposition of the membrane surface was observed due to kinetic demixing. (c) 2012 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 4.636
Times cited: 9
DOI: 10.1016/J.CATTOD.2012.03.005
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“On the relative stabilities of the linear and triangular forms of B3N”. Slanina Z, Martin JML, François JP, Gijbels R, Chemical physics 178, 77 (1993). http://doi.org/10.1016/0301-0104(93)85052-A
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 1.652
Times cited: 9
DOI: 10.1016/0301-0104(93)85052-A
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“Anion rearrangements in fluorinated Nd2CuO3.5”. Corbel G, Attfield JP, Hadermann J, Abakumov AM, Alekseeva AM, Rozova MG, Antipov EV, Chemistry of materials 15, 189 (2003). http://doi.org/10.1021/cm021102m
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 9
DOI: 10.1021/cm021102m
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“[SrF0.8(OH)0.2]2.526[Mn6O12]: columnar rock-salt fragments inside the todorokite-type tunnel structure”. Abakumov AM, Hadermann J, Van Tendeloo G, Kovba ML, Skolis YY, Mudretsova SN, Antipov EV, Volkova OS, Vasiliev AN, Tristan N, Klingeler R, Büchner B, Chemistry of materials 19, 1181 (2007). http://doi.org/10.1021/cm062508s
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 9
DOI: 10.1021/cm062508s
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“Theoretical investigation of grain size tuning during prolonged bias-enhanced nucleation”. Eckert M, Mortet V, Zhang L, Neyts E, Verbeeck J, Haenen ken, Bogaerts A, Chemistry of materials 23, 1414 (2011). http://doi.org/10.1021/cm102481y
Abstract: In this paper, the effects of prolonged bias-enhanced nucleation (prolonged BEN) on the growth mechanisms of diamond are investigated by molecular dynamics (MD) and combined MD-Metropolis Monte Carlo (MD-MMC) simulations. First, cumulative impacts of CxHy+ and Hx+ on an a-C:H/nanodiamond composite were simulated; second, nonconsecutive impacts of the dominant ions were simulated in order to understand the observed phenomena in more detail. As stated in the existing literature, the growth of diamond structures during prolonged BEN is a process that takes place below the surface of the growing film. The investigation of the penetration behavior of CxHy+ and Hx+ species shows that the carbon-containing ions remain trapped within this amorphous phase where they dominate mechanisms like precipitation of sp3 carbon clusters. The H+ ions, however, penetrate into the crystalline phase at high bias voltages (>100 V), destroying the perfect diamond structure. The experimentally measured reduction of grain sizes at high bias voltage, reported in the literature, might thus be related to penetrating H+ ions. Furthermore, the CxHy+ ions are found to be the most efficient sputtering agents, preventing the build up of defective material.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 9.466
Times cited: 9
DOI: 10.1021/cm102481y
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“Plasma-enhanced atomic layer deposition of silver using Ag(fod)(PEt3) and NH3-plasma”. Minjauw MM, Solano E, Sree SP, Asapu R, Van Daele M, Ramachandran RK, Heremans G, Verbruggen SW, Lenaerts S, Martens JA, Detavernier C, Dendooven J, Chemistry of materials 29, 7114 (2017). http://doi.org/10.1021/ACS.CHEMMATER.7B00690
Abstract: A plasma-enhanced atomic layer deposition (ALD) process using the Ag(fod)(PEt3) precursor [(triethylphosphine)(6,6,7,7,8,8,8-heptafluoro-2,2-dimethy1-3,5-octanedionate)silver(I)] in combination with NH3-plasma is reported. The steady growth rate of the reported process (0.24 +/- 0.03 nm/cycle) was found to be 6 times larger than that of the previously reported Ag ALD process based on the same precursor in combination with H-2-plasma (0.04 +/- 0.02 nm/cycle). The ALD characteristics of the H-2-plasma and NH3-plasma processes were verified. The deposited Ag films were polycrystalline face-centered cubic Ag for both processes. The film morphology was investigated by ex situ scanning electron microscopy and grazing-incidence small-angle X-ray scattering, and it was found that films grown with the NH3-plasma process exhibit a much higher particle areal density and smaller particle sizes on oxide substrates compared to those deposited using the H-2-plasma process. This control over morphology of the deposited Ag is important for applications in catalysis and plasmonics. While films grown with the H-2-plasma process had oxygen impurities (similar to 9 atom %) in the bulk, the main impurity for the NH3-plasma process was nitrogen (similar to 7 atom %). In situ Fourier transform infrared spectroscopy experiments suggest that these nitrogen impurities are derived from NH surface groups generated during the NH3-plasma, which interact with the precursor molecules during the precursor pulse. We propose that the reaction of these surface groups with the precursor leads to additional deposition of Ag atoms during the precursor pulse compared to the H-2-plasma process, which explains the enhanced growth rate of the NH3-plasma process.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 9.466
Times cited: 9
DOI: 10.1021/ACS.CHEMMATER.7B00690
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“Unique properties of core shell Ag@Au nanoparticles for the aptasensing of bacterial cells”. Hamidi-Asl E, Dardenne F, Pilehvar S, Blust R, De Wael K, Chemosensors 4, 16 (2016). http://doi.org/10.3390/CHEMOSENSORS4030016
Abstract: In this article, it is shown that the efficiency of an electrochemical aptasensing device is influenced by the use of different nanoparticles (NPs) such as gold nanoparticles (Au), silver nanoparticles (Ag), hollow gold nanospheres (HGN), hollow silver nanospheres (HSN), silvergold core shell (Ag@Au), goldsilver core shell (Au@Ag), and silvergold alloy nanoparticles (Ag/Au). Among these nanomaterials, Ag@Au core shell NPs are advantageous for aptasensing applications because the core improves the physical properties and the shell provides chemical stability and biocompatibility for the immobilization of aptamers. Self-assembly of the NPs on a cysteamine film at the surface of a carbon paste electrode is followed by the immobilization of thiolated aptamers at these nanoframes. The nanostructured (Ag@Au) aptadevice for Escherichia coli as a target shows four times better performance in comparison to the response obtained at an aptamer modified planar gold electrode. A comparison with other (core shell) NPs is performed by cyclic voltammetry and differential pulse voltammetry. Also, the selectivity of the aptasensor is investigated using other kinds of bacteria. The synthesized NPs and the morphology of the modified electrode are characterized by UV-Vis absorption spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis, and electrochemical impedance spectroscopy.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Times cited: 9
DOI: 10.3390/CHEMOSENSORS4030016
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“Work-function modification of Au and Ag surfaces upon deposition of self-assembled monolayers : influence of the choice of the theoretical approach and the thiol decomposition scheme”. Cornil D, Li H, Wood C, Pourtois G, Bredas J-L, Cornil J, ChemPhysChem : a European journal of chemical physics and physical chemistry 14, 2939 (2013). http://doi.org/10.1002/cphc.201300450
Abstract: We have characterized theoretically the work-function modifications of the (111) surfaces of gold and silver upon deposition of self-assembled monolayers based on methanethiol and trifluoromethanethiol. A comparative analysis is made between the experimental results and those obtained from two widely used approaches based on density functional theory. The contributions to the total work-function modifications are estimated on the basis of two decomposition schemes of the thiol molecules that have been proposed in the literature. The contributions are found to differ significantly between the two approaches, as do the corresponding adsorption energies.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.075
Times cited: 9
DOI: 10.1002/cphc.201300450
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“Photocatalytic removal of soot : unravelling of the reaction mechanism by EPR and in situ FTIR spectroscopy”. Smits M, Ling Y, Lenaerts S, Van Doorslaer S, ChemPhysChem : a European journal of chemical physics and physical chemistry 13, 4251 (2012). http://doi.org/10.1002/CPHC.201200674
Abstract: Photocatalytic soot oxidation is studied on P25 TiO2 as an important model reaction for self-cleaning processes by means of electron paramagnetic resonance (EPR) and Fourier transform infrared (FTIR) spectroscopy. Contacting of carbon black with P25 leads on the one hand to a reduction of the local dioxygen concentration in the powder. On the other hand, the weakly adsorbed radicals on the carbon particles are likely to act as alternative traps for the photogenerated conduction-band electrons. We find furthermore that the presence of dioxygen and oxygen-related radicals is vital for the photocatalytic soot degradation. The complete oxidation of soot to CO2 is evidenced by in situ FTIR spectroscopy, no intermediate CO is detected during the photocatalytic process.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 3.075
Times cited: 9
DOI: 10.1002/CPHC.201200674
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“Microstructural characterization of diamond films deposited on c-BN crystals”. Nistor L, Buschmann V, Ralchenko V, Dinca G, Vlasov I, van Landuyt J, Fuess H, Diamond and related materials
T2 –, 10th European Conference on Diamond, Diamond-Like Materials, Nitrides, and Silicon Carbide (Diamond 1999), SEP 12-17, 1999, PRAGUE, CZECH REPUBLIC 9, 269 (2000). http://doi.org/10.1016/S0925-9635(99)00246-0
Abstract: The morphology and structure of diamond films, deposited on cubic boron nitride (c-BN) crystals by microwave-plasma-enhanced chemical vapor deposition, is studied by high-resolution scanning electron microscopy and micro-Raman spectroscopy. The c-BN crystals, with sizes of 200 to 350 mu m and grown by a high-temperature/high-pressure technique, were embedded in a copper holder, and used as substrates in deposition runs of 15 min to 5 h. The nucleation centers for diamond appear as well-shaped cuboctahedral crystallites, having diameters of approximately 100 nm. With increasing deposition time the diamond crystallites grew larger, forming islands on the c-BN faces. In some cases, epitaxial growth was observed on the (111) c-BN faces where coalesced particles gave rise to very smooth regions. A number of diamond crystals with peculiar shapes are observed, such as a pseudo five-fold symmetry due to multiple twinning. Moreover, both randomly distributed carbon tubes, about 100 nn in diameter and 1 mu m in length, and spherically shaped features are observed in samples prepared under the typical conditions of diamond deposition, this effect being ascribed to the influence of plasma-sputtered copper contamination. Quite unusual diamond crystals with a deep, pyramidal-shaped hole in the middle grew on the copper substrate between the c-BN crystals. (C) 2000 Elsevier Science S.A. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.561
Times cited: 9
DOI: 10.1016/S0925-9635(99)00246-0
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“Local probing of the enhanced field electron emission of vertically aligned nitrogen-doped diamond nanorods and their plasma illumination properties”. Deshmukh S, Sankaran KJ, Srinivasu K, Korneychuk S, Banerjee D, Barman A, Bhattacharya G, Phase DM, Gupta M, Verbeeck J, Leou KC, Lin IN, Haenen K, Roy SS, Diamond and related materials 83, 118 (2018). http://doi.org/10.1016/J.DIAMOND.2018.02.005
Abstract: A detailed conductive atomic force microscopic investigation is carried out to directly image the electron emission behavior for nitrogen-doped diamond nanorods (N-DNRs). Localized emission measurements illustrate uniform distribution of high-density electron emission sites from N-DNRs. Emission sites coupled to nano graphitic phases at the grain boundaries facilitate electron transport and thereby enhance field electron emission from N-DNRs, resulting in a device operation at low turn-on fields of 6.23 V/mu m, a high current density of 1.94 mA/cm(2) (at an applied field of 11.8 V/mu m) and a large field enhancement factor of 3320 with a long lifetime stability of 980 min. Moreover, using N-DNRs as cathodes, a microplasma device that can ignite a plasma at a low threshold field of 390 V/mm achieving a high plasma illumination current density of 3.95 mA/cm2 at an applied voltage of 550 V and a plasma life-time stability for a duration of 433 min was demonstrated.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.561
Times cited: 9
DOI: 10.1016/J.DIAMOND.2018.02.005
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“Rapid classification and quantification of cocaine in seized powders with ATR-FTIR and chemometrics”. Eliaerts J, Dardenne P, Meert N, Van Durme F, Samyn N, Janssens K, De Wael K, Drug testing and analysis 9, 1480 (2017). http://doi.org/10.1002/DTA.2149
Abstract: Traditionally, fast screening for the presence of cocaine in unknown powders is performed by means of colour tests. The major drawbacks of these tests are subjective colour evaluation depending on the operator (50 shades of blue) and a lack of selectivity. An alternative fast screening technique is Fourier Transform InfraRed (FTIR) spectrometry. This technique provides spectra that are difficult to interpret without specialized expertise and showing a lack of sensitivity for the detection of cocaine in mixtures. To overcome these limitations, a portable FTIR spectrometer using Attenuated Total Reflectance (ATR) sampling was combined with a multivariate technique, called Support Vector Machines (SVM). Representative street drug powders (n = 482), seized during the period January 2013 to July 2015, and reference powders (n = 33) were used to build and validate a classification model (n = 515) and a quantification model (n = 378). Both models were compared with the conventional chromatographic techniques. The SVM classification model showed a high sensitivity, specificity and efficiency (99%). The SVM quantification model determined cocaine content with a root mean squared error of prediction (RMSEP) of 6% calculated over a wide working range from 4 to 99 w%. In conclusion, the developed models resulted in a clear output (cocaine detected or cocaine not detected) and a reliable estimation of the cocaine content in a wide variety of mixtures. The ATR-FTIR technique combined with SVM is a straightforward, user-friendly and fast approach for routine classification and quantification of cocaine in seized powders.
Keywords: A1 Journal article; Pharmacology. Therapy; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.469
Times cited: 9
DOI: 10.1002/DTA.2149
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“Cyclist exposure to black carbon, ultrafine particles and heavy metals : an experimental study along two commuting routes near Antwerp, Belgium”. Hofman J, Samson R, Joosen S, Blust R, Lenaerts S, Environmental research 164, 530 (2018). http://doi.org/10.1016/J.ENVRES.2018.03.004
Abstract: Urban environments typically exhibit large atmospheric pollution variation, in both space and time. In contrast to traditional monitoring networks suffering from a limited spatial coverage, mobile platforms enable personalized high-resolution monitoring, providing valuable insights into personal atmospheric pollution exposure, and the identification of potential pollution hotspots. This study evaluated personal cyclist exposure to UFPs, BC and heavy metals whilst commuting near Antwerp, Belgium, by performing mobile measurements with wearable black carbon (BC) and ultrafine particle (UFP) instruments. Loaded micro-aethalometer filterstrips were chemically analysed and the inhaled pollutant dose determined from the exhibited heart rate. Considerable spatial pollutant variation was observed along the travelled routes, with distinct contributions from spatial factors (e.g. traffic intersections, urban park and market) and temporary events. On average 300% higher BC, 20% higher UFP and changing elemental concentrations are observed along the road traffic route (RT), when compared to the bicycle highway route (BH). Although the overall background pollution determines a large portion of the experienced personal exposure (in this case 53% for BC and 40% for UFP), cyclists can influence their personal atmospheric pollution exposure, by selecting less exposed commuting routes. Our results, hereby, strengthen the body of evidence in favour of further policy investments in isolated bicycle infrastructure.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Times cited: 9
DOI: 10.1016/J.ENVRES.2018.03.004
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“Holstein polaron: The effect of coupling to multiple-phonon modes”. Covaci L, Berciu M, Epl 80, 67001 (2007). http://doi.org/10.1209/0295-5075/80/67001
Abstract: We investigate the effects of coupling to multiple-phonon modes on the properties of a Holstein polaron. To this end, we generalize the Momentum Average approximations MA((0)) and MA((1)) to deal with multiple-phonon modes. As for a single-phonon mode, these approximations are found to be numerically very efficient. They become exact for very weak or very strong couplings, and are highly accurate in the intermediate regimes, e.g. the spectral weights obey exactly the first six, respectively eight, sum rules. Our results show that the effect on ground-state properties is cumulative in nature. As a result, if the effective coupling to one mode is much larger than to all the others, this mode effectively determines the ground-state properties. However, even very weak coupling to a second phonon mode has important non-perturbational effects on the higher-energy spectrum, in particular on the dispersion and the phonon statistics of the polaron band. This has important consequences on the analysis and interpretation of data for real materials.
Keywords: A1 Journal article
Impact Factor: 1.957
Times cited: 9
DOI: 10.1209/0295-5075/80/67001
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