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“Band flattening in buckled monolayer graphene”. Milovanović, SP, Andelkovic M, Covaci L, Peeters FM, Physical Review B 102, 245427 (2020). http://doi.org/10.1103/PHYSREVB.102.245427
Abstract: The strain fields of periodically buckled graphene induce a periodic pseudomagnetic field (PMF) that modifies the electronic band structure. From the geometry, amplitude, and period of the periodic pseudomagnetic field, we determine the necessary conditions to access the regime of correlated phases by examining the band flattening. As compared to twisted bilayer graphene the proposed system has the advantages that (1) only a single layer of graphene is needed, (2) one is not limited to hexagonal superlattices, and (3) narrower flat bandwidth and larger separation between flat bands can be induced. We, therefore, propose that periodically strained graphene single layers can become a platform for the exploration of exotic many-body phases.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Impact Factor: 3.7
Times cited: 27
DOI: 10.1103/PHYSREVB.102.245427
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“Influence of M23C6 dissolution on the kinetics of ferrite to austenite transformation in Fe-11Cr-0.06C stainless steel”. Miotti Bettanini A, Ding L, Mithieux J-D, Parrens C, Idrissi H, Schryvers D, Delannay L, Pardoen T, Jacques PJ, Materials &, design 162, 362 (2019). http://doi.org/10.1016/j.matdes.2018.12.005
Abstract: The design of high-strength martensitic stainless steels requires an accurate control over the stability of undesired phases, like carbides and ferrite, which can hamper strength and ductility. Here, the ferrite to austenite transformation in Fe-11Cr-0.06C has been studied with a combined experimental-modelling approach. Experimental observations of the austenization process indicate that austenite growth proceeds in multiple steps, each one characterized by a different transformation rate. DICTRA based modelling reveals that the dissolution of the M23C6 Cr-rich carbides leads to Cr partitioning between austenite and parent phases, which controls the rate of transformation through (i) a soft-impingement effect and (ii) consequent stabilization of the ferrite, which remains untransformed inside chromium-enriched-zones even after prolonged austenization stage. Slow heating rate and smaller initial particle sizes allow the design of ferrite-free microstructure.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.364
Times cited: 3
DOI: 10.1016/j.matdes.2018.12.005
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“Evidence for another low-temperature phase transition in tetragonal Pb(ZrxTi1-x)O3 (x=0.515,0.520)”. Mishra RSK, Pandey D, Lemmens H, Van Tendeloo G, Physical review : B : condensed matter and materials physics 64, 054104 (2001). http://doi.org/10.1103/PhysRevB.64.054101
Abstract: Results of dielectric and resonance frequency (f(r)) measurements below room temperature are presented for Pb(ZrxTi1-x)O-3, x = 0.515 and 0.520. It is shown that the temperature coefficient of f(r) changes sign from negative to positive around 210 and 265 K for x = 0.520 and 200 and 260 K for x = 0.515. Anomalies in the real part of the dielectric constant (epsilon') are observed around the same temperatures at which the temperature coefficient of f(r) changes sign because of the electrostrictive coupling between the elastic and dielectric responses. Low-temperature powder x-ray-diffraction (XRD) data, however, reveal only one transition from the tetragonal to monoclinic phase similar to that reported by Noheda et al. [Phys. Rev. B, 61, 8687 (2000)]. Electron-diffraction data, on the other hand, reveal yet another structural transition at lower temperatures corresponding to the second anomaly in the epsilon' vs T and f(r) vs T curves. This second transition is shown to be a cell-doubling transition not observed by Noheda et al. in their XRD studies. The observation of superlattice reflections raises doubts about the correctness of the Cm space group proposed by Noheda et al. for the monoclinic phase of Pb(ZrxTi(1-x))O-3 below the second transition temperature.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
DOI: 10.1103/PhysRevB.64.054101
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“Strong enhancement of superconductivity in a nanosized Pb bridge”. Misko VR, Fomin VM, Devreese JT, Physical Review B 64, 014517 (2001). http://doi.org/10.1103/PhysRevB.64.014517
Keywords: A1 Journal article; Electron Microscopy for Materials Science (EMAT);
Impact Factor: 3.836
Times cited: 28
DOI: 10.1103/PhysRevB.64.014517
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“Vortex states in a multi-conoid superconducting nanosized bridge”. Misko VR, Fomin VM, Devreese JT, Physica C-Superconductivity And Its Applications 369, 356 (2002). http://doi.org/10.1016/S0921-4534(01)01276-X
Keywords: A1 Journal article; Electron Microscopy for Materials Science (EMAT);
Impact Factor: 1.404
Times cited: 1
DOI: 10.1016/S0921-4534(01)01276-X
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“On the Ginzburg-Landau analysis of a mixed s-dx2-y2-wave superconducting mesoscopic square”. Misko VR, Fomin VM, Devreese JT, Moshchalkov VV, Solid State Communications 114, 499 (2000). http://doi.org/10.1016/S0038-1098(00)00090-9
Keywords: A1 Journal article; Electron Microscopy for Materials Science (EMAT);
Impact Factor: 1.554
Times cited: 2
DOI: 10.1016/S0038-1098(00)00090-9
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“Stability of vortex-antivortex “molecules&rdquo, in mesoscopic superconducting triangles”. Misko VR, Fomin VM, Devreese JT, Moshchalkov VV, 3rd International Symposium on Mesoscopic Superconductivity and, Spintronics, MAR 01-04, 2004, Atsug, 191 (2005). http://doi.org/10.1142/9789812701619_0030
Abstract: We have revealed thermodynamically stable vortex-antivortex configurations in mesoscopic type I superconducting equilateral triangles. The revealed effect is explained by two factors: (i) vortex confinement in mesoscopic triangles and (ii) appearance of the vortex-antivortex repulsion in mesoscopic type I superconductor triangles in the vicinity of the dual point. The stability of the obtained solutions is examined as a function of material and external parameters – the Ginzburg-Landau parameter K and temperature – as well as a function of a distortion of the sample's shape. The vortex-antivortex. “molecule” turns out to be stable in a wide range of the parameters that makes it possible its experimental visualization.
Keywords: A1 Journal article; Electron Microscopy for Materials Science (EMAT);
DOI: 10.1142/9789812701619_0030
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“Stability of vortex-antivortex molecules in mesoscopic superconducting triangles”. Misko VR, Fomin VM, Devreese JT, Moshchalkov VV, Physica C-Superconductivity And Its Applications 404, 251 (2004). http://doi.org/10.1016/j.physc.2003.11.043
Keywords: A1 Journal article; Electron Microscopy for Materials Science (EMAT);
Impact Factor: 1.404
Times cited: 2
DOI: 10.1016/j.physc.2003.11.043
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“Stable vortex-antivortex molecules in mesoscopic superconducting triangles”. Misko VR, Fomin VM, Devreese JT, Moshchalkov VV, Physical Review Letters 90, 147003 (2003). http://doi.org/10.1103/PhysRevLett.90.147003
Keywords: A1 Journal article; Electron Microscopy for Materials Science (EMAT);
Impact Factor: 8.462
Times cited: 103
DOI: 10.1103/PhysRevLett.90.147003
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“Vortex states in a mescopic superconducting triangle”. Misko VR, Fomin VM, Devreese JT, Moshchalkov VV, Physica C-Superconductivity And Its Applications 369, 361 (2002). http://doi.org/10.1016/S0921-4534(01)01277-1
Keywords: A1 Journal article; Electron Microscopy for Materials Science (EMAT);
Impact Factor: 1.404
Times cited: 14
DOI: 10.1016/S0921-4534(01)01277-1
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“Polytypism in mcalpineite : a study of natural and synthetic Cu₃TeO₆”. Missen OP, Mills SJ, Canossa S, Hadermann J, Nenert G, Weil M, Libowitzky E, Housley RM, Artner W, Kampf AR, Rumsey MS, Spratt J, Momma K, Dunstan MA, Acta Crystallographica. Section B: Structural Science, Crystal Engineering and Materials (Online) 78 (2022). http://doi.org/10.1107/S2052520621013032
Abstract: Synthetic and naturally occurring forms of tricopper orthotellurate, (Cu3TeO6)-Te-II-O-IV (the mineral mcalpineite) have been investigated by 3D electron diffraction (3D ED), X-ray powder diffraction (XRPD), Raman and infrared (IR) spectroscopic measurements. As a result of the diffraction analyses, (Cu3TeO6)-Te-II-O-IV is shown to occur in two polytypes. The higher-symmetric (Cu3TeO6)-Te-II-O-IV-1C polytype is cubic, space group 1a (3) over bar, with a = 9.537 (1) angstrom and V = 867.4 (3) angstrom(3) as reported in previous studies. The 1C polytype is a well characterized structure consisting of alternating layers of (CuO6)-O-II octahedra and both (CuO6)-O-II and (TeO6)-O-VI octahedra in a patchwork arrangement. The structure of the lower-symmetric orthorhombic (Cu3TeO6)-Te-II-O-IV-2O polytype was determined for the first time in this study by 3D ED and verified by Rietveld refinement. The 2O polytype crystallizes in space group Pcca, with a = 9.745 (3) angstrom, b = 9.749 (2) angstrom, c = 9.771 (2) angstrom and V = 928.3 (4) angstrom(3) . High-precision XRPD data were also collected on (Cu3TeO6)-Te-II-O-IV-2O to verify the lower-symmetric structure by performing a Rietveld refinement. The resultant structure is identical to that determined by 3D ED, with unit-cell parameters a = 9.56157 (19) angstrom, b = 9.55853 (11) angstrom, c = 9.62891 (15) angstrom and V = 880.03 (2) angstrom(3) . The lower symmetry of the 2O polytype is a consequence of a different cation ordering arrangement, which involves the movement of every second (CuO6)-O-II and (TeO6)-O-VI octahedral layer by (1/4, 1/4, 0), leading to an offset of (TeO6)-O-VI and (CuO6)-O-II octahedra in every second layer giving an ABAB* stacking arrangement. Syntheses of (Cu3TeO6)-Te-II-O-IV showed that low-temperature (473 K) hydrothermal conditions generally produce the 2O polytype. XRPD measurements in combination with Raman spectroscopic analysis showed that most natural mcalpineite is the orthorhombic 2O polytype. Both XRPD and Raman spectroscopy measurements may be used to differentiate between the two polytypes of (Cu3TeO6)-Te-II-O-IV. In Raman spectroscopy, (Cu3TeO6)-Te-II-O-IV-1C has a single strong band around 730 cm(-1), whereas (Cu3TeO6)-Te-II-O-IV-2O shows a broad double maximum with bands centred around 692 and 742 cm(-1).
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.9
DOI: 10.1107/S2052520621013032
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“Oxide superconductors: electron microscopy”. Mitchell TE, Gronsky R, Van Tendeloo G Pergamon Press, Oxford, page 401 (1992).
Keywords: H3 Book chapter; Electron microscopy for materials research (EMAT)
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“Synthesis and characterization of a highly electroactive composite based on Au nanoparticles supported on nanoporous activated carbon for electrocatalysis”. Moggia G, Hoekx S, Daems N, Bals S, Breugelmans T, ChemElectroChem , 1 (2023). http://doi.org/10.1002/CELC.202300293
Abstract: A facile, “one-pot”, chemical approach to synthesize gold-based nanoparticles finely dispersed on porous activated carbon (Norit) was demonstrated in this work. The pH of the synthesis bath played a critical role in determining the optimal gold-carbon interaction, which enabled a successful deposition of the gold nanoparticles onto the carbon matrix with a maximized metal utilization of 93 %. The obtained AuNP/C nanocomposite was characterized using SEM, HAADF-STEM electron tomography and electrochemical techniques. It was found that the Au nanoparticles, with diameters between 5 and 20 nm, were evenly distributed over the carbon matrix, both inside and outside the pores. Electrochemical characterization indicated that the composite had a very large electroactive surface area (EASA), as high as 282.4 m2 gAu-1. By exploiting its very high EASA, the catalyst was intended to boost the productivity of glucaric acid in the electrooxidation of its precursor, gluconic acid. However, cyclic voltammetry experiments revealed a very limited reactivity towards gluconic acid oxidation, due to the spacial hindrance of gluconic acid molecule which prevented diffusion inside the catalyst nanopores. On the other hand, the as-synthesized nanocomposite promises to be effective towards the ORR, and might thus find potential application as anode catalyst for fuel cells as well as for the scalability of all those electrochemical reactions involving small molecules with high diffusivity and catalysed by noble metals (i. e. CO2, CH4, N2, etc..). Electrocatalysis: Gold nanoparticles with diameter between 5 and 20 nm evenly distributed onto porous activated carbon (Norit) were obtained using a facile “one-pot” chemical synthesis technique with very high metal utilization. The AuNP/C nanocomposite was characterized using SEM, HAADF-STEM electron tomography and electrochemical techniques, revealing a very large electroactive surface area (EASA). The figure shows the HAADF-STEM image (a) and the respective EDX elemental distribution (b) for the AuNP/C composite with 9.3 % Au-loading developed in this work (Au is marked in red and C in green).image
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Applied Electrochemistry & Catalysis (ELCAT)
Impact Factor: 4
Times cited: 1
DOI: 10.1002/CELC.202300293
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“Interlayer structure in YBCO-coated conductors prepared by chemical solution deposition”. Molina L, Egoavil R, Turner S, Thersleff T, Verbeeck J, Holzapfel B, Eibl O, Van Tendeloo G, Superconductor science and technology 26, 075016 (2013). http://doi.org/10.1088/0953-2048/26/7/075016
Abstract: The functionality of YBa2Cu3O7−δ (YBCO)-coated conductor technology depends on the reliability and microstructural properties of a given tape or wire architecture. Particularly, the interface to the metal tape is of interest since it determines the adhesion, mechanical stability of the film and thermal contact of the film to the substrate. A trifluoroacetate (TFA)metal organic deposition (MOD) prepared YBCO film deposited on a chemical solution-derived buffer layer architecture based on CeO2/La2Zr2O7 and grown on a flexible Ni5 at.%W substrate with a {100}⟨001⟩ biaxial texture was investigated. The YBCO film had a thickness was 440 nm and a jc of 1.02 MA cm−2 was determined at 77 K and zero external field. We present a sub-nanoscale analysis of a fully processed solution-derived YBCO-coated conductor by aberration-corrected scanning transmission electron microscopy (STEM) combined with electron energy-loss spectroscopy (EELS). For the first time, structural and chemical analysis of the valence has been carried out on the sub-nm scale. Intermixing of Ni, La, Ce, O and Ba takes place at these interfaces and gives rise to nanometer-sized interlayers which are a by-product of the sequential annealing process. Two distinct interfacial regions were analyzed in detail: (i) the YBCO/CeO2/La2Zr2O7 region (10 nm interlayer) and (ii) the La2Zr2O7/Ni5 at.%W substrate interface region (20 nm NiO). This is of particular significance for the functionality of these YBCO-coated conductor architectures grown by chemical solution deposition.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.878
Times cited: 11
DOI: 10.1088/0953-2048/26/7/075016
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“Barrier efficiency of sponge-like La2Zr2O7 buffer layers for YBCO-coated conductors”. Molina L, Tan H, Biermans E, Batenburg KJ, Verbeeck J, Bals S, Van Tendeloo G, Superconductor science and technology 24, 065019 (2011). http://doi.org/10.1088/0953-2048/24/6/065019
Abstract: Solution derived La2Zr2O7 films have drawn much attention for potential applications as thermal barriers or low-cost buffer layers for coated conductor technology. Annealing and coating parameters strongly affect the microstructure of La2Zr2O7, but different film processing methods can yield similar microstructural features such as nanovoids and nanometer-sized La2Zr2O7 grains. Nanoporosity is a typical feature found in such films and the implications for the functionality of the films are investigated by a combination of scanning transmission electron microscopy (STEM), electron energy-loss spectroscopy (EELS) and quantitative electron tomography. Chemical solution based La2Zr2O7 films deposited on flexible Ni5 at.%W substrates with a {100}lang001rang biaxial texture were prepared for an in-depth characterization. A sponge-like structure composed of nanometer-sized voids is revealed by high-angle annular dark-field scanning transmission electron microscopy in combination with electron tomography. A three-dimensional quantification of nanovoids in the La2Zr2O7 film is obtained on a local scale. Mostly non-interconnected highly faceted nanovoids compromise more than one-fifth of the investigated sample volume. The diffusion barrier efficiency of a 170 nm thick La2Zr2O7 film is investigated by STEM-EELS, yielding a 1.8 ± 0.2 nm oxide layer beyond which no significant nickel diffusion can be detected and intermixing is observed. This is of particular significance for the functionality of YBa2Cu3O7 − δ coated conductor architectures based on solution derived La2Zr2O7 films as diffusion barriers.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 2.878
Times cited: 31
DOI: 10.1088/0953-2048/24/6/065019
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“Atomic and electronic structures of BaHfO3-doped TFA-MOD-derived YBa2Cu3O7−δthin films”. Molina-Luna L, Duerrschnabel M, Turner S, Erbe M, Martinez GT, Van Aert S, Holzapfel B, Van Tendeloo G, Superconductor science and technology 28, 115009 (2015). http://doi.org/10.1088/0953-2048/28/11/115009
Abstract: Tailoring the properties of oxide-based nanocomposites is of great importance for a wide range of materials relevant for energy technology. YBa2Cu3O7−δ (YBCO) superconducting thin films containing nanosized BaHfO3 (BHO) particles yield a significant improvement of the magnetic flux pinning properties and a reduced anisotropy of the critical current density. These films were prepared by chemical solution deposition (CSD) on (100) SrTiO3 (STO) substrates yielding critical current densities up to 3.6 MA cm−2 at 77 K and self-field. Transport in-field J c measurements demonstrated a high pinning force maximum of around 6 GN/m3 for a sample annealed at T = 760 °C that has a doping of 12 mol% of BHO. This sample was investigated by scanning transmission electron microscopy (STEM) in combination with electron energy-loss spectroscopy (EELS) yielding strain and spectral maps. Spherical BHO nanoparticles of 15 nm in size were found in the matrix, whereas the particles at the interface were flat. A 2 nm diffusion layer containing Ti was found at the YBCO (BHO)/STO interface. Local lattice deformation mapping at the atomic scale revealed crystal defects induced by the presence of both sorts of BHO nanoparticles, which can act as pinning centers for magnetic flux lines. Two types of local lattice defects were identified and imaged: (i) misfit edge dislocations and (ii) Ba-Cu-Cu-Ba stacking faults (Y-248 intergrowths). The local electronic structure and charge transfer were probed by high energy resolution monochromated electron energy-loss spectroscopy. This technique made it possible to distinguish superconducting from non-superconducting areas in nanocomposite samples with atomic resolution in real space, allowing the identification of local pinning sites on the order of the coherence length of YBCO (~1.5 nm) and the determination of 0.25 nm dislocation cores.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.878
Times cited: 4
DOI: 10.1088/0953-2048/28/11/115009
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“A novel explanation for the increased conductivity in annealed Al-doped ZnO: an insight into migration of aluminum and displacement of zinc”. Momot A, Amini MN, Reekmans G, Lamoen D, Partoens B, Slocombe DR, Elen K, Adriaensens P, Hardy A, Van Bael MK, Physical chemistry, chemical physics 19, 27866 (2017). http://doi.org/10.1039/C7CP02936E
Abstract: A combined experimental and first-principles study is performed to study the origin of conductivity in
ZnO:Al nanoparticles synthesized under controlled conditions via a reflux route using benzylamine as a
solvent. The experimental characterization of the samples by Raman, nuclear magnetic resonance (NMR)
and conductivity measurements indicates that upon annealing in nitrogen, the Al atoms at interstitial
positions migrate to the substitutional positions, creating at the same time Zn interstitials. We provide
evidence for the fact that the formed complex of AlZn and Zni corresponds to the origin of the Knight
shifted peak (KS) we observe in 27Al NMR. As far as we know, the role of this complex has not been
discussed in the literature to date. However, our first-principles calculations show that such a complex is
indeed energetically favoured over the isolated Al interstitial positions. In our calculations we also
address the charge state of the Al interstitials. Further, Zn interstitials can migrate from Al_Zn and possibly
also form Zn clusters, leading to the observed increased conductivity.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.123
Times cited: 26
DOI: 10.1039/C7CP02936E
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“Restructuring of titanium oxide overlayers over nickel nanoparticles during catalysis”. Monai M, Jenkinson K, Melcherts AEM, Louwen JN, Irmak EA, Van Aert S, Altantzis T, Vogt C, van der Stam W, Duchon T, Smid B, Groeneveld E, Berben P, Bals S, Weckhuysen BM, Science 380, 644 (2023). http://doi.org/10.1126/SCIENCE.ADF6984
Abstract: Reducible supports can affect the performance of metal catalysts by the formation of suboxide overlayers upon reduction, a process referred to as the strong metal-support interaction (SMSI). A combination of operando electron microscopy and vibrational spectroscopy revealed that thin TiOx overlayers formed on nickel/titanium dioxide catalysts during 400 degrees C reduction were completely removed under carbon dioxide hydrogenation conditions. Conversely, after 600 degrees C reduction, exposure to carbon dioxide hydrogenation reaction conditions led to only partial reexposure of nickel, forming interfacial sites in contact with TiOx and favoring carbon-carbon coupling by providing a carbon species reservoir. Our findings challenge the conventional understanding of SMSIs and call for more-detailed operando investigations of nanocatalysts at the single-particle level to revisit static models of structure-activity relationships.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Applied Electrochemistry & Catalysis (ELCAT)
Impact Factor: 56.9
Times cited: 29
DOI: 10.1126/SCIENCE.ADF6984
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“Deeper insights into the photoluminescence properties and (photo)chemical reactivity of cadmium red (CdS1-xSex) paints in renowned twentieth century paintings by state-of-the-art investigations at multiple length scales”. Monico L, Rosi F, Vivani R, Cartechini L, Janssens K, Gauquelin N, Chezganov D, Verbeeck J, Cotte M, D'Acapito F, Barni L, Grazia C, Buemi LP, Andral J-L, Miliani C, Romani A, The European Physical Journal Plus 137, 311 (2022). http://doi.org/10.1140/EPJP/S13360-022-02447-7
Abstract: Cadmium red is the name used for denoting a class of twentieth century artists' pigments described by the general formula CdS1-xSex. For their vibrant hues and excellent covering power, a number of renowned modern and contemporary painters, including Jackson Pollock, often used cadmium reds. As direct band gap semiconductors, CdS1-xSex compounds undergo direct radiative recombination (with emissions from the green to orange region) and radiative deactivation from intragap trapping states due to crystal defects, which give rise to two peculiar red-NIR emissions, known as deep level emissions (DLEs). The positions of the DLEs mainly depend on the Se content of CdS1-xSex; thus, photoluminescence and diffuse reflectance vis-NIR spectroscopy have been profitably used for the non-invasive identification of different cadmium red varieties in artworks over the last decade. Systematic knowledge is however currently lacking on what are the parameters related to intrinsic crystal defects of CdS1-xSex and environmental factors influencing the spectral properties of DLEs as well as on the overall (photo)chemical reactivity of cadmium reds in paint matrixes. Here, we present the application of a novel multi-length scale and multi-method approach to deepen insights into the photoluminescence properties and (photo)chemical reactivity of cadmium reds in oil paintings by combining both well established and new non-invasive/non-destructive analytical techniques, including macro-scale vis-NIR and vibrational spectroscopies and micro-/nano-scale advanced electron microscopy mapping and X-ray methods employing synchrotron radiation and conventional sources. Macro-scale vis-NIR spectroscopy data obtained from the in situ non-invasive analysis of nine masterpieces by Gerardo Dottori, Jackson Pollock and Nicolas de Stael allowed classifying the CdS1-xSex-paints in three groups, according to the relative intensity of the two DLE bands. These outcomes, combined with results from micro-/nano-scale electron microscopy mapping and X-ray analysis of a set of CdS1-xSex powders and artificially aged paint mock-ups, indicated that the relative intensity of DLEs is not affected by the morphology, microstructure and local atomic environment of the pigment particles but it is influenced by the presence of moisture. Furthermore, the extensive study of artificially aged oil paint mock-ups permitted us to provide first evidence of the tendency of cadmium reds toward photo-degradation and to establish that the conversion of CdS1-xSex to CdSO4 and/or oxalates is triggered by the oil binding medium and moisture level and depends on the Se content. Based on these findings, we could interpret the localized presence of CdSO4 and cadmium oxalate as alteration products of the original cadmium red paints in two paintings by Pollock.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Antwerp X-ray Imaging and Spectroscopy (AXIS)
Impact Factor: 3.4
Times cited: 3
DOI: 10.1140/EPJP/S13360-022-02447-7
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“Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of synchrotron X-ray spectromicroscopy and related methods : 1 : artificially aged model samples”. Monico L, van der Snickt G, Janssens K, de Nolf W, Miliani C, Verbeeck J, Tian H, Tan H, Dik J, Radepont M, Cotte M, Analytical chemistry 83, 1214 (2011). http://doi.org/10.1021/ac102424h
Abstract: On several paintings by artists of the end of the 19th century and the beginning of the 20th Century a darkening of the original yellow areas, painted with the chrome yellow pigment (PbCrO4, PbCrO4·xPbSO4, or PbCrO4·xPbO) is observed. The most famous of these are the various Sunflowers paintings Vincent van Gogh made during his career. In the first part of this work, we attempt to elucidate the degradation process of chrome yellow by studying artificially aged model samples. In view of the very thin (1−3 μm) alteration layers that are formed, high lateral resolution spectroscopic methods such as microscopic X-ray absorption near edge (μ-XANES), X-ray fluorescence spectrometry (μ-XRF), and electron energy loss spectrometry (EELS) were employed. Some of these use synchrotron radiation (SR). Additionally, microscopic SR X-ray diffraction (SR μ-XRD), μ-Raman, and mid-FTIR spectroscopy were employed to completely characterize the samples. The formation of Cr(III) compounds at the surface of the chrome yellow paint layers is particularly observed in one aged model sample taken from a historic paint tube (ca. 1914). About two-thirds of the chromium that is present at the surface has reduced from the hexavalent to the trivalent state. The EELS and μ-XANES spectra are consistent with the presence of Cr2O3·2H2O (viridian). Moreover, as demonstrated by μ-XANES, the presence of another Cr(III) compound, such as either Cr2(SO4)3·H2O or (CH3CO2)7Cr3(OH)2 [chromium(III) acetate hydroxide], is likely.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 6.32
Times cited: 113
DOI: 10.1021/ac102424h
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“Microstructure and properties of oxygen controlled melt textured NdBaCuO superconductive ceramics”. Monot I, Tancret F, Laffez P, Van Tendeloo G, Desgardin G, Technology 65, 26 (1999). http://doi.org/10.1016/S0921-5107(99)00193-2
Abstract: Nd1+xBa2-xCu3O7-delta (123) bulk superconductors have been synthesised by the oxygen controlled melt growth method. Unlike the YBaCuO system, platinum doping or Nd4Ba2Cu2O10 (422) rich compositions do not refine the peritectic '422' secondary phase, but the latter improves the microstructural quality. Low oxygen partial pressure and high purity precursors are necessary to achieve in a reproducible manner high T-c and J(c) (up to 56 000 A/cm(2) in 0T and 30 000 A/cm(2) under 1.5T). The fishtail effect observed at 77 K is compared with the one observed in the YBCO system, and is discussed in terms of oxygen deficiency, Nd-Ba substitution, defects and vortex lattice. Our TEM observations did not evidence any Nd-Ba substituted clusters in the Nd123 matrix; however, some diffuse streaks, observed in the [100] zone ED pattern, support the fact that the source of the peak effect in this system is mainly due to oxygen disorder and low stability of the orthorhombic phase. (C) 1999 Elsevier Science S.A. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.552
Times cited: 5
DOI: 10.1016/S0921-5107(99)00193-2
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“Microstructure and flux pinning properties of melt textured grown doped YBa2Cu3O7-\delta”. Monot I, Verbist K, Hervieu M, Laffez P, Delamare MP, Wang J, Desgardin G, Van Tendeloo G, Physica: C : superconductivity 274, 253 (1997)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.404
Times cited: 33
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“Composite Supraparticles with Tunable Light Emission”. Montanarella F, Altantzis T, Zanaga D, Rabouw FT, Bals S, Baesjou P, Vanmaekelbergh D, van Blaaderen A, ACS nano 11, 9136 (2017). http://doi.org/10.1021/acsnano.7b03975
Abstract: Robust luminophores emitting light with broadly tunable colors are desirable in many applications such as light-emitting diode (LED)-based lighting, displays, integrated optoelectronics and biology. Nanocrystalline quantum dots with multicolor emission, from core- and shell-localized excitons, as well as solid layers of mixed quantum dots that emit different colors have been proposed. Here, we report on colloidal supraparticles that are composed of three types of Cd(Se,ZnS) core/(Cd,Zn)S shell nanocrystals with emission in the red, green, and blue. The emission of the supraparticles can be varied from pure to composite colors over the entire visible region and finetuned into variable shades of white light by mixing the nanocrystals in controlled proportions. Our approach results in supraparticles with sizes spanning the colloidal domain and beyond that combine versatility and processability with a broad, stable, and tunable emission, promising applications in lighting devices and biological research.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 36
DOI: 10.1021/acsnano.7b03975
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“Microstructure and mechanical properties of Hastelloy X produced by HP-SLM (high power selective laser melting)”. Montero-Sistiaga ML, Pourbabak S, Van Humbeeck J, Schryvers D, Vanmeensel K, Materials &, design 165, 107598 (2019). http://doi.org/10.1016/j.matdes.2019.107598
Abstract: In order to increase the production rate during selective laser melting (SLM), a high power laser with a large beam diameter is used to build fully dense Hastelloy X parts. Compared to SLM with a low power and small diameter beam, the productivity was increased from 6 mm3/s to 16 mm3/s, i.e. 2.6 times faster. Besides the productivity benefit, the influence of the use of a high power laser on the rapid solidification microstructure and concomitant material properties is highlighted. The current paper compares the microstructure and tensile properties of Hastelloy X built with low and high power lasers. The use of a high power laser results in wider and shallower melt pools inducing an enhanced morphological and crystallographic texture along the building direction (BD). In addition, the increased heat input results in coarser sub-grains or high density dislocation walls for samples processed with a high power laser. Additionally, the influence of hot isostatic pressing (HIP) as a post-processing technique was evaluated. After HIP, the tensile fracture strain increased as compared to the strain in the as-built state and helped in obtaining competitive mechanical properties as compared to conventionally processed Hastelloy X parts.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.364
Times cited: 15
DOI: 10.1016/j.matdes.2019.107598
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“On the use of TEM in the characterization of nanocomposites”. Monticelli O, Musina Z, Russo S, Bals S, Materials letters 61, 3446 (2007). http://doi.org/10.1016/j.matlet.2006.11.086
Abstract: Both an organically modified commercial clay of montmorillonite type (MMT) and its nanocomposites, based either on polyamide 6 (PA6) or an epoxy resin, as matrix polymer, have been characterized by transmission electron microscopy (TEM). Sample micrographs, taken at increasing exposure times (t(e)), have shown the gradual disappearance of clay layers, because of an amorphisation of the MMT crystalline structures caused by prolonged sample exposure to electron beam. Indeed, the above phenomenon, which is mostly evident in the case of intercalated nanocomposites, makes the detection of the layered silicate dispersion in the polymer matrix rather difficult and compels to perform TEM measurements using very short exposure times. Moreover, the microscopy accelerating voltage has turned out to affect sample stability; namely, when decreasing the above parameter, the disappearance of clay structure occurs at lower exposure times. (C) 2006 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.572
Times cited: 28
DOI: 10.1016/j.matlet.2006.11.086
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“Evaluation of top, angle, and side cleaned FIB samples for TEM analysis”. Montoya E, Bals S, Rossell MD, Schryvers D, Van Tendeloo G, Microscopy research and technique 70, 1060 (2007). http://doi.org/10.1002/jemt.20514
Abstract: ITEM specimens of a LaAlO3/SrTiO3 multilayer are prepared by FIB with internal lift out. Using a Ga+1 beam of 5 kV, a final cleaning step yielding top, top-angle, side, and bottom-angle cleaning is performed. Different cleaning procedures, which can be easily implemented in a dual beam FIB system, are described and compared; all cleaning types produce thin lamellae, useful for HRTEM and HAADF-STEM work up to atomic resolution. However, the top cleaned lamellae are strongly affected by the curtain effect. Top-angle cleaned specimens show an amorphous layer of around 5 nm at the specimen surfaces, due to damage and redeposition. Furthermore, it is observed that the LaAlO3 layers are preferentially destroyed and transformed into amorphous material, during the thinning process.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.147
Times cited: 36
DOI: 10.1002/jemt.20514
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“Redeposition and differential sputtering of La in transmission electron microscopy samples of LaAIO3/SrTiO3 multilayers prepared by focused ion beam”. Montoya E, Bals S, Van Tendeloo G, Journal of microscopy 231, 359 (2008). http://doi.org/10.1111/j.1365-2818.2008.02055.x
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.692
DOI: 10.1111/j.1365-2818.2008.02055.x
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“The effect of microstructure on the hydrogenation of Mg/Fe thin film multilayers”. Mooij L, Perkisas T, Palsson G, Schreuders H, Wolff M, Hjorvarsson B, Bals S, Dam B, International journal of hydrogen energy 39, 17092 (2014). http://doi.org/10.1016/j.ijhydene.2014.08.035
Abstract: Nanoconfined magnesium hydride can be simultaneously protected and thermodynamically destabilized when interfaced with materials such as Ti and Fe. We study the hydrogenation of thin layers of Mg (<14 nm) nanoconfined in one dimension within thin film Fe/Mg/Fe/Pd multilayers by the optical technique Hydrogenography. The hydrogenation of nanosized magnesium layers in Fe/Mg/Fe multilayers surprisingly shows the presence of multiple plateau pressures, whose nature is thickness dependent. In contrast, hydrogen desorption occurs via a single plateau which does not depend on the Mg layer thickness. From structural and morphological analyses with X-ray diffraction/reflectometry and cross-section TEM, we find that the Mg layer roughness is large when deposited on Fe and furthermore contains high-angle grain boundaries (GB's). When grown on Ti, the Mg layer roughness is low and no high-angle GB's are detected. From a Ti/Mg/Fe multilayer, in which the Mg layer is flat and has little or no GB's, we conclude that MgH2 is indeed destabilized by the interface with Fe. In this case, both the ab- and desorption plateau pressures are increased by a factor two compared to the hydrogenation of Mg within Ti/Mg/Ti multilayers. We hypothesize that the GB's in the Fe/Mg/Fe multilayer act as diffusion pathways for Pd, which is known to greatly alter the hydrogenation behavior of Mg when the two materials share an interface. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.582
Times cited: 15
DOI: 10.1016/j.ijhydene.2014.08.035
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“Designer phospholipid capping ligands for soft metal halide nanocrystals”. Morad V, Stelmakh A, Svyrydenko M, Feld LG, Boehme SC, Aebli M, Affolter J, Kaul CJ, Schrenker NJ, Bals S, Sahin Y, Dirin DN, Cherniukh I, Raino G, Baumketner A, Kovalenko MV, Nature 626, 542 (2024). http://doi.org/10.1038/S41586-023-06932-6
Abstract: The success of colloidal semiconductor nanocrystals (NCs) in science and optoelectronics is inextricable from their surfaces. The functionalization of lead halide perovskite NCs1-5 poses a formidable challenge because of their structural lability, unlike the well-established covalent ligand capping of conventional semiconductor NCs6,7. We posited that the vast and facile molecular engineering of phospholipids as zwitterionic surfactants can deliver highly customized surface chemistries for metal halide NCs. Molecular dynamics simulations implied that ligand-NC surface affinity is primarily governed by the structure of the zwitterionic head group, particularly by the geometric fitness of the anionic and cationic moieties into the surface lattice sites, as corroborated by the nuclear magnetic resonance and Fourier-transform infrared spectroscopy data. Lattice-matched primary-ammonium phospholipids enhance the structural and colloidal integrity of hybrid organic-inorganic lead halide perovskites (FAPbBr3 and MAPbBr3 (FA, formamidinium; MA, methylammonium)) and lead-free metal halide NCs. The molecular structure of the organic ligand tail governs the long-term colloidal stability and compatibility with solvents of diverse polarity, from hydrocarbons to acetone and alcohols. These NCs exhibit photoluminescence quantum yield of more than 96% in solution and solids and minimal photoluminescence intermittency at the single particle level with an average ON fraction as high as 94%, as well as bright and high-purity (about 95%) single-photon emission. Phospholipids enhance the structural and colloidal integrity of hybrid organic-inorganic lead halide perovskites and lead-free metal halide nanocrystals, which then exhibit enhanced robustness and optical properties.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 64.8
DOI: 10.1038/S41586-023-06932-6
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“Surface processes during purification of InP quantum dots”. Mordvinova N, Emelin P, Vinokurov A, Dorofeev S, Abakumov A, Kuznetsova T, Beilstein journal of nanotechnology 5, 1220 (2014). http://doi.org/10.3762/bjnano.5.135
Abstract: Recently, a new simple and fast method for the synthesis of InP quantum dots by using phosphine as phosphorous precursor and myristic acid as surface stabilizer was reported. Purification after synthesis is necessary to obtain samples with good optical properties. Two methods of purification were compared and the surface processes which occur during purification were studied. Traditional precipitation with acetone is accompanied by a small increase in photoluminescence. It occurs that during the purification the hydrolysis of the indium precursor takes place, which leads to a better surface passivation. The electrophoretic purification technique does not increase luminescence efficiency but yields very pure quantum dots in only a few minutes. Additionally, the formation of In(OH)(3) during the low temperature synthesis was explained. Purification of quantum dots is a very significant part of post-synthetical treatment that determines the properties of the material. But this subject is not sufficiently discussed in the literature. The paper is devoted to the processes that occur at the surface of quantum dots during purification. A new method of purification, electrophoresis, is investigated and described in particular.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.127
Times cited: 5
DOI: 10.3762/bjnano.5.135
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