“A Facet-Specific Quantum Dot Passivation Strategy for Colloid Management and Efficient Infrared Photovoltaics”. Kim Y, Che F, Jo JW, Choi J, de Arquer FPG, Voznyy O, Sun B, Kim J, Choi M-J, Quintero-Bermudez R, Fan F, Tan CS, Bladt E, Walters G, Proppe AH, Zou C, Yuan H, Bals S, Hofkens J, Roeffaers MBJ, Hoogland S, Sargent EH, Advanced materials 31, 1805580 (2019). http://doi.org/10.1002/ADMA.201805580
Abstract: Colloidal nanocrystals combine size- and facet-dependent properties with solution processing. They offer thus a compelling suite of materials for technological applications. Their size- and facet-tunable features are studied in synthesis; however, to exploit their features in optoelectronic devices, it will be essential to translate control over size and facets from the colloid all the way to the film. Larger-diameter colloidal quantum dots (CQDs) offer the attractive possibility of harvesting infrared (IR) solar energy beyond absorption of silicon photovoltaics. These CQDs exhibit facets (nonpolar (100)) undisplayed in small-diameter CQDs; and the materials chemistry of smaller nanocrystals fails consequently to translate to materials for the short-wavelength IR regime. A new colloidal management strategy targeting the passivation of both (100) and (111) facets is demonstrated using distinct choices of cations and anions. The approach leads to narrow-bandgap CQDs with impressive colloidal stability and photoluminescence quantum yield. Photophysical studies confirm a reduction both in Stokes shift (approximate to 47 meV) and Urbach tail (approximate to 29 meV). This approach provides a approximate to 50% increase in the power conversion efficiency of IR photovoltaics compared to controls, and a approximate to 70% external quantum efficiency at their excitonic peak.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 19.791
Times cited: 74
DOI: 10.1002/ADMA.201805580
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“The domain configuration of the Au11In3 phase”. Kifune K, Yamamoto K, Maruyama S, Van Tendeloo G, Philosophical magazine letters 69, 211 (1994). http://doi.org/10.1080/09500839408241594
Abstract: The crystal structure of Au11In3 thin film alloys have been analysed by means of electron diffraction and high-resolution electron microscopy. The electron diffraction pattern and the high-resolution electron microscopy revealed that this structure was incommensurate and had a domain structure consisting of three kinds of structural unit. The approximant structural model, which is based on a h.c.p. stacking of the layers, is hexagonal with lattice parameters a = 7.612 nm and c = 0-478 nm.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.087
Times cited: 2
DOI: 10.1080/09500839408241594
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“'Natural' and 'man-made' platelets in type-la diamonds”. Kiflawi I, Bruley J, Luyten W, Van Tendeloo G, Philosophical magazine: B: physics of condensed matter: electronic, optical and magnetic properties 78, 299 (1998). http://doi.org/10.1080/13642819808205733
Abstract: 'Natural' platelets are planar defects in {001} planes found in natural type-IaA/B diamonds. 'Man-made' platelets are platelets formed in the laboratory by annealing type-IaA diamonds at temperatures over 2500 degrees C. Careful study shows that the infrared (IR) spectra of the 'man-made' platelets are different from the IR spectra of 'natural' platelets. High-temperature (T greater than or equal to 2000 degrees C) annealing of platelets containing type-IaA/B diamonds modifies the IR absorption spectrum owing to the 'natural' platelets and makes it similar to the IR spectrum of the 'man-made' platelets. It is suggested that such high-temperature annealing changes the structure of the 'natural' platelets. The changes are too subtle to be detected by electron microscopy techniques. Topographic electron-energy-loss spectroscopy shows that platelets contain nitrogen at an average density of 0.7 atoms per a(0)(2); however, high-temperature annealing does not seem to affect the concentration of the nitrogen in the platelets.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 13
DOI: 10.1080/13642819808205733
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“New molybdenum oxides Ag4M2Zr(MoO4)6 (M=Mg, Mn, Co, Zn) with a channel-like structure”. Khobrakova ET, Morozov VA, Khasanov SS, Tsyrenova GD, Khaikina EG, Lebedev OI, Van Tendeloo G, Lazoryak BI, Solid state sciences 7, 1397 (2005). http://doi.org/10.1016/j.solidstatesciences.2005.08.010
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.811
Times cited: 9
DOI: 10.1016/j.solidstatesciences.2005.08.010
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“The path towards efficient wide band gap thin-film kesterite solar cells with transparent back contact for viable tandem application”. Khelifi S, Brammertz G, Choubrac L, Batuk M, Yang S, Meuris M, Barreau N, Hadermann J, Vrielinck H, Poelman D, Neyts K, Vermang B, Lauwaert J, Solar Energy Materials And Solar Cells 219, 110824 (2021). http://doi.org/10.1016/j.solmat.2020.110824
Abstract: Wide band gap thin-film kesterite solar cell based on non-toxic and earth-abundant materials might be a suitable candidate as a top cell for tandem configuration in combination with crystalline silicon as a bottom solar cell. For this purpose and based on parameters we have extracted from electrical and optical characterization techniques of Cu2ZnGeSe4 absorbers and solar cells, a model has been developed to describe the kesterite top cell efficiency limitations and to investigate the different possible configurations with transparent back contact for fourterminal tandem solar cell application. Furthermore, we have studied the tandem solar cell performance in view of the band gap and the transparency of the kesterite top cell and back contact engineering. Our detailed analysis shows that a kesterite top cell with efficiency > 14%, a band gap in the range of 1.5-1.7 eV and transparency above 80% at the sub-band gaps photons energies are required to achieve a tandem cell with higher efficiency than with a single silicon solar cell.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.784
DOI: 10.1016/j.solmat.2020.110824
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“Correlation between the nanocrystalline Sm(Fe,Mo)12 and its out of equilibrium phase Sm(Fe,Mo)10”. Khazzan S, Bessais L, Van Tendeloo G, Mliki N, Journal of magnetism and magnetic materials 363, 125 (2014). http://doi.org/10.1016/j.jmmm.2014.03.030
Abstract: Nanostructured Sm-Fe-Mo semi-hard magnetic material exhibiting enhanced magnetic properties can be produced by ball milling followed by recrystallization. Milled samples were annealed for 30 min in a vacuum at different temperatures (T-A) between 700 and 1190 degrees C. The effects of heat treatment and Mo content on structural and magnetic property changes have been investigated by means of X-ray diffraction using the Rietvekl method, transmission electron microscopy and magnetic measurements. For samples annealed at T-A > 900 degrees C the tetragonal ThMn12-type structure is identified, while for 700 < T-A < 900 degrees C a new out of equilibrium P6/mmm type structure was found as the major phase. This novel nanocrystalline phase has never been synthesized before. The correspondent stoichiometry is determined on the basis of the vacancy model. The Rietveld analysis gives a stoichiometry ratio equal to 1:10, for the out of equilibrium hexagonal phase, which is described with three crystallographic transition metal sites: 3g is fully occupied, 61 occupation is limited to hexagons surrounding the Fe dumbbell pairs 2e. We have performed a magnetic and structural study of nanocrystalline metastable P6/mrnm Sm(Fe1-xMo)(10), correlated with structural transformation towards its equilibrium derivative 14/mrnm Sm(Fe1-xMo)(12). A maximum of the coercive field H-C (H-C > 5 kOe) has been observed for the new hexagonal P6/rnmm phase suggesting that nanocrystalline Sm(Fe,Mo)(10), is a semi hard material, and is potential candidate for magnetic recording. (C) 2014 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.63
Times cited: 6
DOI: 10.1016/j.jmmm.2014.03.030
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“A new structure type of the ternary sulfide Eu1.3Nb1.9S5”. Khasanova NR, Van Tendeloo G, Lebedev OI, Amelinckx S, Grippa AY, Abakumov AM, Istomin SY, D'yachenko OG, Antipov EV, Journal of solid state chemistry 164, 345 (2002). http://doi.org/10.1006/jssc.2001.9501
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.299
Times cited: 2
DOI: 10.1006/jssc.2001.9501
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“Synthesis, structure and properties of layered bismuthates: (Ba,K)3Bi2O7 and (Ba,K)2BiO4”. Khasanova NR, Kovba ML, Putilin SN, Antipov EV, Lebedev OI, Van Tendeloo G, Solid state communications 122, 189 (2002). http://doi.org/10.1016/S0038-1098(02)00096-0
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.554
Times cited: 3
DOI: 10.1016/S0038-1098(02)00096-0
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“Biocompatibility and corrosion behavior of the shape memory NiTi alloy in the physiological environments simulated with body fluids for medical applications”. Khalil-Allafi J, Amin-Ahmadi B, Zare M, Materials science and engineering: part C: biomimetic materials 30, 1112 (2010). http://doi.org/10.1016/j.msec.2010.06.007
Abstract: Due to unique properties of NiTi shape memory alloys such as high corrosion resistance, biocompatibility, super elasticity and shape memory behavior, NiTi shape memory alloys are suitable materials for medical applications. Although TiO2 passive layer in these alloys can prevent releasing of nickel to the environment, high nickel content and stability of passive layer in these alloys are very debatable subjects. In this study a NiTi shape memory alloy with nominal composition of 50.7 atom% Ni was investigated by corrosion tests. Electrochemical tests were performed in two physiological environments of Ringer solution and NaCl 0.9% solution. Results indicate that the breakdown potential of the NiTi alloy in NaCl 0.9% solution is higher than that in Ringer solution. The results of Scanning Electron Microscope (SEM) reveal that low pitting corrosion occurred in Ringer solution compared with NaCl solution at potentiostatic tests. The pH value of the solutions increases after the electrochemical tests. The existence of hydride products in the X-ray diffraction analysis confirms the decrease of the concentration of hydrogen ion in solutions. Topographical evaluations show that corrosion products are nearly same in all samples. The biocompatibility tests were performed by reaction of mouse fibroblast cells (L929). The growth and development of cells for different times were measured by numbering the cells or statistics investigations. The figures of cells for different times showed natural growth of cells. The different of the cell numbers between the test specimen and control specimen was negligible; therefore it may be concluded that the NiTi shape memory alloy is not toxic in the physiological environments simulated with body fluids.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.164
Times cited: 34
DOI: 10.1016/j.msec.2010.06.007
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“Effect of mold hardness on microstructure and contraction porosity in ductile cast iron”. Khalil-Allafi J, Amin-Ahmadi B, Journal of iron and steel research international 18, 44 (2011). http://doi.org/10.1016/S1006-706X(11)60048-4
Abstract: The effect of mold hardness on the microstructure of ductile iron and the contraction porosity was investigated. Molds with different hardnesses (0.41, 0.48, 0.55, 0.62 MPa) and a sand mold prepared by Co2 method were used. The influence of silicon content on the induced expansion pressure owing to the formation of graphite was also investigated. The contraction during solidification can be compensated by an induced expansion owing to the graphite relief when the hardness of mold increases; therefore, the possibility of achieving a sound product without using any riser increases.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 0.836
Times cited: 1
DOI: 10.1016/S1006-706X(11)60048-4
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“Influence of mold preheating and silicon content on microstructure and casting properties of ductile iron in permanent mold”. Khalil-Allafi J, Amin-Ahmadi B, Journal of iron and steel research international 18, 34 (2011). http://doi.org/10.1016/S1006-706X(11)60034-4
Abstract: The effects of the mold preheating and the silicon content of ductile iron on the percentage of carbides, graphite nodule counts and shrinkage volume were investigated. The results showed that the percentage of carbides and the shrinkage volume decreased when the mold preheating increased. The ductile iron with the carbon equivalent of 4.45% and the silicon content of 2.5% without any porosity defects was achieved when the mold preheating was 450 °C. Increasing the silicon content in the range of 2.1%3.3% led to the increase in graphite nodule count and graphite size and the decrease in percentage of carbides. It is due to the increase in induced expansion pressure during the graphite formation with the increasing of silicon content. The suitable condition for casting a sound product of ductile iron without the riser at the mold preheating temperature of 300 °C is the silicon content of 3.3% and carbon equivalent of 4.7%.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 0.836
Times cited: 3
DOI: 10.1016/S1006-706X(11)60034-4
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“Multiple-step martensitic transformations in the Ni51Ti49 single crystal”. Khalil-Allafi J, Amin-Ahmadi B, Journal of materials science 45, 6440 (2010). http://doi.org/10.1007/s10853-010-4729-4
Abstract: Multiple-step martensitic transformations of an aged Ni51Ti49 single crystal using calorimetric method were investigated. Results show that for short aging times (1045 min) multiple-step martensitic transformations on cooling occur in two steps. Applying intermediate aging times (1.254 h) results in three steps and long aging times (more than 8 h) lead to two-step martensitic transformations again. This behavior has not been recognized in NiTi single crystals in literatures. It can be related to the heterogeneity of composition and stress fields around Ni4Ti3 precipitates.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.599
Times cited: 5
DOI: 10.1007/s10853-010-4729-4
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“Atomically dispersed ruthenium hydride on beta zeolite as catalysts for the isomerization of muconates”. Khalil I, Rigamonti MG, Janssens K, Bugaev A, Arenas Esteban D, Robijns S, Donckels T, Beydokhti MT, Bals S, De Vos D, Dusselier M, Nature Catalysis 7, 921 (2024). http://doi.org/10.1038/S41929-024-01205-5
Abstract: Searching for sustainable polymers requires access to biomass-based monomers. In that sense, glucose-derived cis,cis-muconic acid stands as a high-potential intermediate. However, to unlock its potential, an isomerization to the value-added trans,trans-isomer, trans,trans-muconic acid, is required. Here we develop atomically dispersed low-loaded Ru on beta zeolite catalysts that produce trans,trans-muconate in ethanol with total conversion (to equilibrium) and a selectivity of >95%. We reach very high turnovers per Ru and productivity rates of 427 mM h(-1) (similar to 85 g l(-1) h(-1)), surpassing the bio-based cis,cis-muconic acid production rates by an order of magnitude. By coupling isomerization to Diels-Alder cycloaddition, terephthalate intermediates are produced in around 90% yields, circumventing the isomer equilibrium. Isomerization is promoted by Ru hydride species where the hydrides are generated from the alcohol solvent, as evidenced by Fourier transform infrared spectroscopy. Beyond isomerization, the Ru-zeolite and its hydride-forming capacity could be of use as a heterogeneous catalyst for other hydride chemistries, demonstrated by a successful hydride transfer hydrogenation.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 37.8
DOI: 10.1038/S41929-024-01205-5
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“Self-directed localization of ZIF-8 thin film formation by conversion of ZnO nanolayers”. Khaletskaya K, Turner S, Tu M, Wannapaiboon S, Schneemann A, Meyer R, Ludwig A, Van Tendeloo G, Fischer RA, Advanced functional materials 24, 4804 (2014). http://doi.org/10.1002/adfm.201400559
Abstract: Control of localized metal-organic framework (MOF) thin film formation is a challenge. Zeolitic imidazolate frameworks (ZIFs) are an important sub-class of MOFs based on transition metals and imidazolate linkers. Continuous coatings of intergrown ZIF crystals require high rates of heterogeneous nucleation. In this work, substrates coated with zinc oxide layers are used, obtained by atomic layer deposition (ALD) or by magnetron sputtering, to provide the Zn2+ ions required for nucleation and localized growth of ZIF-8 films ([Zn(mim)(2)]; Hmim = 2-methylimidazolate). The obtained ZIF-8 films reveal the expected microporosity, as deduced from methanol adsorption studies using an environmentally controlled quartz crystal microbalance (QCM) and comparison with bulk ZIF-8 reference data. The concept is transferable to other MOFs, and is applied to the formation of [Al(OH)(1,4-ndc)](n) (ndc = naphtalenedicarboxylate) thin films derived from Al2O3 nanolayers.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
Times cited: 77
DOI: 10.1002/adfm.201400559
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Khaletskaya K (2014) Functional metal-organic frameworks : from bulk to surface engineered properties. Antwerpen
Keywords: Doctoral thesis; Electron microscopy for materials research (EMAT)
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“High-TCInterfacial Ferromagnetism in SrMnO3/LaMnO3Superlattices”. Keunecke M, Lyzwa F, Schwarzbach D, Roddatis V, Gauquelin N, Müller-Caspary K, Verbeeck J, Callori SJ, Klose F, Jungbauer M, Moshnyaga V, Advanced functional materials , 1808270 (2019). http://doi.org/10.1002/adfm.201808270
Abstract: Heterostructures of strongly correlated oxides demonstrate various intriguing and potentially useful interfacial phenomena. LaMnO3/SrMnO3 superlattices are presented showcasing a new high‐temperature ferromagnetic phase with Curie temperature, TC ≈360 K, caused by electron transfer from the surface of the LaMnO3 donor layer into the neighboring SrMnO3 acceptor layer. As a result, the SrMnO3 (top)/LaMnO3 (bottom) interface shows an enhancement of the magnetization as depth‐profiled by polarized neutron reflectometry. The length scale of charge transfer, λTF ≈2 unit cells, is obtained from in situ growth monitoring by optical ellipsometry, supported by optical simulations, and further confirmed by high resolution electron microscopy and spectroscopy. A model of the inhomogeneous distribution of electron density in LaMnO3/SrMnO3 layers along the growth direction is concluded to account for a complex interplay between ferromagnetic and antiferromagnetic layers in superlattices.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 15.621
Times cited: 26
DOI: 10.1002/adfm.201808270
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“High-performance CO2-selective hybrid membranes by exploiting MOF-breathing effects”. Kertik A, Wee LH, Şentosun K, Navarro JAR, Bals S, Martens JA, Vankelecom IFJ, Acs Applied Materials &, Interfaces 12, 2952 (2020). http://doi.org/10.1021/ACSAMI.9B17820
Abstract: Conventional CO2 separation in the petrochemical industry via cryogenic distillation or amine-based absorber-stripper units is energy-intensive and environmentally unfriendly. Membrane-based gas separation technology, in contrast, has contributed significantly to the development of energy-efficient systems for processes such as natural gas purification. The implementation of commercial polymeric membranes in gas separation processes is restricted by their permeability-selectivity trade-off and by their insufficient thermal and chemical stability. Herein, we present the fabrication of a Matrimid-based membrane loaded with a breathing metal-organic framework (MOF) (NH2-MIL-53(Al)) which is capable of separating binary CO2/CH4 gas mixtures with high selectivities without sacrificing much of its CO2 permeabilities. NH2-MIL-53(Al) crystals were embedded in a polyimide (PI) matrix, and the mixed-matrix membranes (MMMs) were treated at elevated temperatures (up to 350 degrees C) in air to trigger PI cross-linking and to create PI-MOF bonds at the interface to effectively seal the grain boundary. Most importantly, the MOF transitions from its narrow-pore form to its large-pore form during this treatment, which allows the PI chains to partly penetrate the pores and cross-link with the amino functions at the pore mouth of the NH2-MIL-53(Al) and stabilizes the open-pore form of NH2-MIL-53(Al). This cross-linked MMM, with MOF pore entrances was made more selective by the anchored PI-chains and achieves outstanding CO2/CH4 selectivities. This approach provides significant advancement toward the design of selective MMMs with enhanced thermal and chemical stabilities which could also be applicable for other potential applications, such as separation of hydrocarbons (olefin/paraffin or isomers), pervaporation, and solvent-resistant nanofiltration.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 9.5
Times cited: 26
DOI: 10.1021/ACSAMI.9B17820
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“Highly selective gas separation membrane using in situ amorphised metal-organic frameworks”. Kertik A, Wee LH, Pfannmöller M, Bals S, Martens JA, Vankelecom IFJ, Energy &, environmental science 10, 2342 (2017). http://doi.org/10.1039/C7EE01872J
Abstract: Conventional carbon dioxide (CO2) separation in the petrochemical industry via cryogenic distillation is energy intensive and environmentally unfriendly. Alternatively, polymer membrane-based separations are of significant interest owing to low production cost, low-energy consumption and ease of upscaling. However, the implementation of commercial polymeric membranes is limited by their permeability and selectivity trade-off and the insufficient thermal and chemical stability. Herein, a novel type of amorphous mixed matrix membrane (MMM) able to separate CO2/CH4 mixtures with the highest selectivities ever reported for MOF based MMMs is presented. The MMM consists of an amorphised metal-organic framework (MOF) dispersed in an oxidatively cross-linked matrix achieved by fine tuning of the thermal treatment temperature in air up to 350 degrees C which drastically boosts the separation properties of the MMM. Thanks to the protection of the surrounding polymer, full oxidation of this MOF (i.e. ZIF-8) is prevented, and amorphisation of the MOF is realized instead, thus in situ creating a molecular sieve network. In addition, the treatment also improves the filler-polymer adhesion and induces an oxidative cross-linking of the polyimide matrix, resulting in MMMs with increased stability or plasticization resistance at high pressure up to 40 bar, marking a new milestone as new molecular sieve MOF MMMs for challenging natural gas purification applications. A new field for the use of amorphised MOFs and a variety of separation opportunities for such MMMs are thus opened.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 29.518
Times cited: 122
DOI: 10.1039/C7EE01872J
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“Self-Assembly of Pluronic F127—Silica Spherical Core–Shell Nanoparticles in Cubic Close-Packed Structures”. Kerkhofs S, Willhammar T, Van Den Noortgate H, Kirschhock CEA, Breynaert E, Van Tendeloo G, Bals S, Martens JA, Chemistry of materials 27, 5161 (2015). http://doi.org/10.1021/acs.chemmater.5b01772
Abstract: A new ordered mesoporous silica material (COK-19) with cubic symmetry is synthesized by silicate polycondensation in a citric acid/citrate buffered micellar solution of Pluronic F127 triblock copolymer near neutral pH. SAXS, nitrogen adsorption, TEM, and electron tomography reveal the final material has a cubic close packed symmetry (Fm3̅m) with isolated spherical mesopores interconnected through micropores. Heating of the synthesis medium from room temperature to 70 °C results in a mesopore size increase from 7.0 to 11.2 nm. Stepwise addition of the silicate source allows isolation of a sequence of intermediates that upon characterization with small-angle X-ray scattering uncovers the formation process via formation and aggregation of individual silica-covered Pluronic micelles.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 39
DOI: 10.1021/acs.chemmater.5b01772
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“Microwave plasma-based dry reforming of methane: Reaction performance and carbon formation”. Kelly S, Mercer E, De Meyer R, Ciocarlan R-G, Bals S, Bogaerts A, Journal of CO2 utilization 75, 102564 (2023). http://doi.org/10.1016/j.jcou.2023.102564
Abstract: e investigate atmospheric pressure microwave (MW) plasma (2.45 GHz) conversion in CO2 and CH4 mixtures (i.e., dry reforming of methane, DRM) focusing on reaction performance and carbon formation. Promising energy costs of ~2.8–3.0 eV/molecule or ~11.1–11.9 kJ/L are amongst the best performance to date considering the current state-of-the-art for plasma-based DRM for all types of plasma. The conversion is in the range of ~46–49% and ~55–67% for CO2 and CH4, respectively, producing primarily syngas (i.e., H2 and CO) with H2/CO ratios of ~0.6–1 at CH4 fractions ranging from 30% to 45%. Water is the largest byproduct with levels ranging ~7–14% in the exhaust. Carbon particles visibly impact the plasma at higher CH4 fractions (> 30%), where they become heated and incandescent. Particle luminosity increases with increasing CH4 fractions, with the plasma becoming unstable near a 1:1 mixture (i.e., > 45% CH4). Electron microscopy of the carbon material reveals an agglomerated morphology of pure carbon nanoparticles. The mean particle size is determined as ~20 nm, free of any metal contamination, consistent with the electrode-less MW design.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.7
Times cited: 6
DOI: 10.1016/j.jcou.2023.102564
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“Increasing the solubility limit for tetrahedral aluminium in ZnO:Al nanorods by variation in synthesis parameters”. Kelchtermans A, Adriaensens P, Slocombe D, Kuznetsov VL, Hadermann J, Riskin A, Elen K, Edwards PP, Hardy A, Van Bael MK, Journal of nanomaterials 2015, 1 (2015). http://doi.org/10.1155/2015/546041
Abstract: Nanocrystalline ZnO:Al nanoparticles are suitable building blocks for transparent conductive layers. As the concentration of substitutional tetrahedral Al is an important factor for improving conductivity, here we aim to increase the fraction of substitutional Al. To this end, synthesis parameters of a solvothermal reaction yielding ZnO:Al nanorods were varied. A unique set of complementary techniques was combined to reveal the exact position of the aluminium ions in the ZnO lattice and demonstrated its importance in order to evaluate the potential of ZnO:Al nanocrystals as optimal building blocks for solution deposited transparent conductive oxide layers. Both an extension of the solvothermal reaction time and stirring during solvothermal treatment result in a higher total tetrahedral aluminium content in the ZnO lattice. However, only the longer solvothermal treatment effectively results in an increase of the substitutional positions aimed for.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 1.871
Times cited: 2
DOI: 10.1155/2015/546041
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“Observations of intermetallic compound formation of hot dip aluminized steel”. Kee-Hyun K, van Daele B, Van Tendeloo G, Jong-Kyu Y, Aluminium alloys: part 1-2 519-521, 1871 (2006)
Abstract: A hot dip aluminizing process to simulate the continuous galvanizing line (CGL) was carried out in three successive steps by a hot dip simulator: the pre-treatment for removing scales on the 200 x 250 mm(2) and 1mm in thickness cold rolled steel sheet, the dipping in 660 degrees C Al-Si melt for 3s and the cooling. In a pre-treatment, the steel specimen was partly coated by Au to confirm the mechanism of intermetallic compound (IMC) formation. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) analyses were followed to observe the cross-section and the distribution of the elements. The specimen was analyzed in the boundary of the dipped-undipped part to see the formation mechanism of the aluminized steel. An intermetallic compound (IMC) is rapidly developed and grown in the steel-liquid interface. It has been usually reported that the IMC was formed by the dissolution of iron in the steel substrate toward the melt and the diffusion of aluminum in an opposite direction. The specimen is covered with aluminum-10 wt.% silicon, forms the IMC in the part that was not Au coated. However, IMC is not formed in the Au-coated part. The interface of the dipped-undipped is also analyzed by EDX. At the interface of the steel-IMC, it is clearly shown that the IMC is only formed in the dipped part and exists in the steel substrate as well, and contributes by iron, aluminum and silicon. The result clearly shows that only aluminum diffuses into the steel substrate without the dissolution of iron and forms the IMC between the steel substrate and the melt. Au coating and the short dipping time prevent the iron from dissolving into the aluminum melt. By TEM combined with focused ion beam (FIB) sample preparation, the IMC is confirmed as Fe2SiAl8, a hexagonal structure with space group P6(3)/mmc.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
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“Possibilities and limitations of advanced transmission electron microscopy for carbon-based nanomaterials”. Ke X, Bittencourt C, Van Tendeloo G, Beilstein journal of nanotechnology 6, 1541 (2015). http://doi.org/10.3762/bjnano.6.158
Abstract: A major revolution for electron microscopy in the past decade is the introduction of aberration correction, which enables one to increase both the spatial resolution and the energy resolution to the optical limit. Aberration correction has contributed significantly to the imaging at low operating voltages. This is crucial for carbon-based nanomaterials which are sensitive to electron irradiation. The research of carbon nanomaterials and nanohybrids, in particular the fundamental understanding of defects and interfaces, can now be carried out in unprecedented detail by aberration-corrected transmission electron microscopy (AC-TEM). This review discusses new possibilities and limits of AC-TEM at low voltage, including the structural imaging at atomic resolution, in three dimensions and spectroscopic investigation of chemistry and bonding. In situ TEM of carbon-based nanomaterials is discussed and illustrated through recent reports with particular emphasis on the underlying physics of interactions between electrons and carbon atoms.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.127
Times cited: 10
DOI: 10.3762/bjnano.6.158
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“Low-dose patterning of platinum nanoclusters on carbon nanotubes by focused-electron-beam-induced deposition as studied by TEM”. Ke X, Bittencourt C, Bals S, Van Tendeloo G, Beilstein journal of nanotechnology 4, 77 (2013). http://doi.org/10.3762/bjnano.4.9
Abstract: Focused-electron-beam-induced deposition (FEBID) is used as a direct-write approach to decorate ultrasmall Pt nanoclusters on carbon nanotubes at selected sites in a straightforward maskless manner. The as-deposited nanostructures are studied by transmission electron microscopy (TEM) in 2D and 3D, demonstrating that the Pt nanoclusters are well-dispersed, covering the selected areas of the CNT surface completely. The ability of FEBID to graft nanoclusters on multiple sides, through an electron-transparent target within one step, is unique as a physical deposition method. Using high-resolution TEM we have shown that the CNT structure can be well preserved thanks to the low dose used in FEBID. By tuning the electron-beam parameters, the density and distribution of the nanoclusters can be controlled. The purity of as-deposited nanoclusters can be improved by low-energy electron irradiation at room temperature.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.127
Times cited: 12
DOI: 10.3762/bjnano.4.9
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“TEM sample preparation by FIB for carbon nanotube interconnects”. Ke X, Bals S, Romo Negreira A, Hantschel T, Bender H, Van Tendeloo G, Ultramicroscopy 109, 1353 (2009). http://doi.org/10.1016/j.ultramic.2009.06.011
Abstract: A powerful method to study carbon nanotubes (CNTs) grown in patterned substrates for potential interconnects applications is transmission electron microscopy (TEM). However, high-quality TEM samples are necessary for such a study. Here, TEM specimen preparation by focused ion beam (FIB) has been used to obtain lamellae of patterned samples containing CNTs grown inside contact holes. A dual-cap Pt protection layer and an extensive 5 kV cleaning procedure are applied in order to preserve the CNTs and avoid deterioration during milling. TEM results show that the inner shell structure of the carbon nanotubes has been preserved, which proves that focused ion beam is a useful technique to prepare TEM samples of CNT interconnects.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.843
Times cited: 21
DOI: 10.1016/j.ultramic.2009.06.011
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“Three-dimensional analysis of carbon nanotube networks in interconnects by electron tomography without missing wedge artifacts”. Ke X, Bals S, Cott D, Hantschel T, Bender H, Van Tendeloo G, Microscopy and microanalysis 16, 210 (2010). http://doi.org/10.1017/S1431927609991371
Abstract: The three-dimensional (3D) distribution of carbon nanotubes (CNTs) grown inside semiconductor contact holes is studied by electron tomography. The use of a specialized tomography holder results in an angular tilt range of ±90°, which means that the so-called missing wedge is absent. The transmission electron microscopy (TEM) sample for this purpose consists of a micropillar that is prepared by a dedicated procedure using the focused ion beam (FIB) but keeping the CNTs intact. The 3D results are combined with energy dispersive X-ray spectroscopy (EDS) to study the relation between the CNTs and the catalyst particles used during their growth. The reconstruction, based on the full range of tilt angles, is compared with a reconstruction where a missing wedge is present. This clearly illustates that the missing wedge will lead to an unreliable interpretation and will limit quantitative studies
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.891
Times cited: 42
DOI: 10.1017/S1431927609991371
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Ke X (2010) From top-down to bottom-up : from carbon nanotubes to nanodevices. Antwerpen
Keywords: Doctoral thesis; Electron microscopy for materials research (EMAT)
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“Synthesis and crystal structure of Sr2ScBiO6”. Kazin PE, Abakumov AM, Zaytsev DD, Tretyakov YD, Khasanova NR, Van Tendeloo G, Jansen M, Journal of solid state chemistry 162, 142 (2001). http://doi.org/10.1006/jssc.2001.9375
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.299
Times cited: 3
DOI: 10.1006/jssc.2001.9375
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“Uniform patterns of Fe-vacancy ordering in the Kx(Fe,Co)2-ySe2 superconductors”. Kazakov SM, Abakumov AM, Perz-Mato JM, Ovchinnikov AV, Roslova MV, Boltalin AI, Morozov IV, Antipov EV, Van Tendeloo G, Chemistry of materials 23, 4311 (2011). http://doi.org/10.1021/cm201203h
Abstract: The Fe-vacancy ordering patterns in the superconducting KxFe2ySe2 and nonsuperconducting Kx(Fe,Co)2ySe2 samples have been investigated by electron diffraction and high angle annular dark field scanning transmission electron microscopy. The Fe-vacancy ordering occurs in the ab plane of the parent ThCr2Si2-type structure, demonstrating two types of patterns. Superstructure I retains the tetragonal symmetry and can be described with the aI = bI = as√5 (as is the unit cell parameter of the parent ThCr2Si2-type structure) supercell and I4/m space group. Superstructure II reduces the symmetry to orthorhombic with the aII = as√2, bII = 2as√2 supercell and the Ibam space group. This type of superstructure is observed for the first time in KxFe2ySe2. The Fe-vacancy ordering is inhomogeneous: the disordered areas interleave with the superstructures I and II in the same crystallite. The observed superstructures represent the compositionally dependent uniform ordering patterns of two species (the Fe atoms and vacancies) on a square lattice. More complex uniform ordered configurations, including compositional stripes, can be predicted for different chemical compositions of the KxFe2ySe2 (0 < y < 0.5) solid solutions.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 20
DOI: 10.1021/cm201203h
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“Quantitative 3D Investigation of Nanoparticle Assemblies by Volumetric Segmentation of Electron Tomography Data Sets”. Kavak S, Kadu AA, Claes N, Sánchez-Iglesias A, Liz-Marzán LM, Batenburg KJ, Bals S, The journal of physical chemistry: C : nanomaterials and interfaces 127, 9725 (2023). http://doi.org/10.1021/acs.jpcc.3c02017
Abstract: Morphological characterization of nanoparticle assemblies and hybrid nanomaterials is critical in determining their structure-property relationships as well as in the development of structures with desired properties. Electron tomography has become a widely utilized technique for the three-dimensional characterization of nanoparticle assemblies. However, the extraction of quantitative morphological parameters from the reconstructed volume can be a complex and labor-intensive task. In this study, we aim to overcome this challenge by automating the volumetric segmentation process applied to three-dimensional reconstructions of nanoparticle assemblies. The key to enabling automated characterization is to assess the performance of different volumetric segmentation methods in accurately extracting predefined quantitative descriptors for morphological characterization. In our methodology, we compare the quantitative descriptors obtained through manual segmentation with those obtained through automated segmentation methods, to evaluate their accuracy and effectiveness. To show generality, our study focuses on the characterization of assemblies of CdSe/CdS quantum dots, gold nanospheres and CdSe/CdS encapsulated in polymeric micelles, and silica-coated gold nanorods decorated with both CdSe/CdS or PbS quantum dots. We use two unsupervised segmentation algorithms: the watershed transform and the spherical Hough transform. Our results demonstrate that the choice of automated segmentation method is crucial for accurately extracting the predefined quantitative descriptors. Specifically, the spherical Hough transform exhibits superior performance in accurately extracting quantitative descriptors, such as particle size and interparticle distance, thereby allowing for an objective, efficient, and reliable volumetric segmentation of complex nanoparticle assemblies.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.7
Times cited: 2
DOI: 10.1021/acs.jpcc.3c02017
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