|
“Stabilization and encapsulation of gold nanostars mediated by dithiols”. Wang Y, Belén Serrano A, Sentosun K, Bals S, Liz-Marzán LM, Small 11, 4314 (2015). http://doi.org/10.1002/smll.201500703
Abstract: Surface chemistry plays a pivotal role in regulating the morphology of nanoparticles, maintaining colloidal stability, and mediating the interaction with target analytes toward practical applications such as surface-enhanced Raman scattering (SERS)-based sensing and imaging. The use of a binary ligand mixture composed of 1,4-benzenedithiol (BDT) and hexadecyltrimethylammonium chloride (CTAC) to provide gold nanostars with long-term stability is reported. This is despite BDT being a bifunctional ligand, which usually leads to bridging and loss of colloidal stability. It is found however that neither BDT nor CTAC alone are able to provide sufficient colloidal and chemical stability. BDT-coated Au nanostars are additionally used as seeds to direct the encapsulation with a gold outer shell, leading to the formation of unusual nanostructures including semishell-coated gold nanostars, which are characterized by high-resolution electron microscopy and electron tomography. Finally, BDT is exploited as a probe to reveal the enhanced local electric fields in the different nanostructures, showing that the semishell configuration provides significantly high SERS signals as compared to other coreshell configurations obtained during seeded growth, including full shells.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 8.643
Times cited: 36
DOI: 10.1002/smll.201500703
|
|
|
“Strain accommodation through facet matching in La1.85Sr0.15CuO4/Nd1.85Ce0.15CuO4 ramp-edge junctions”. Hoek M, Coneri F, Poccia N, Renshaw Wang X, Ke X, Van Tendeloo G, Hilgenkamp H, APL materials 3, 086101 (2015). http://doi.org/10.1063/1.4927796
Abstract: Scanning nano-focused X-ray diffraction and high-angle annular dark-field scanning transmission electron microscopy are used to investigate the crystal structure of ramp-edge junctions between superconducting electron-doped Nd1.85Ce0.15CuO4 and superconducting hole-doped La1.85Sr0.15CuO4 thin films, the latter being the top layer. On the ramp, a new growth mode of La1.85Sr0.15CuO4 with a 3.3° tilt of the c-axis is found. We explain the tilt by developing a strain accommodation model that relies on facet matching, dictated by the ramp angle, indicating that a coherent domain boundary is formed at the interface. The possible implications of this growth mode for the creation of artificial domains in morphotropic materials are discussed.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.335
Times cited: 4
DOI: 10.1063/1.4927796
|
|
|
“Chemical stability of YBiO3 buffer layers for implementation in YBa2Cu3O7-&delta, coated conductors”. Pollefeyt G, Meledin A, Pop C, Ricart S, Hühne R, Van Tendeloo G, Van Driessche I, Acta materialia 100, 224 (2015). http://doi.org/10.1016/j.actamat.2015.08.023
Abstract: In this work, the chemical and microstructural stability of YBiO3 buffer layers during the growth of YBa2Cu3O7-δ (YBCO) was studied. The superconducting YBCO films were deposited via both Pulsed Laser Deposition as well as Chemical Solution Deposition. Although excellent superconducting properties are obtained in both cases, self-field critical current densities of 3.6 and 1.2 MA/cm2 respectively, chemical instability of the YBiO3 buffer layer is observed. An elaborate transmission electron microscopy study showed that in the case of vacuum deposited YBCO, the YBiO3 becomes unstable and Bi2O3 sublimates out of the architecture. Due to this structural instability, an intermediate Y2O3 layer is obtained which maintains it microstructural orientation relation with the substrate and acts as growth template for YBCO. For chemical solution deposited YBCO, reaction of YBCO with the YBiO3 buffer layer is observed, leading to large grains of YBa2BiO6 which are pushed towards the surface of the films and strongly reduce the superconducting properties. Upon using high growth temperatures for the superconducting layer, these secondary phases decompose, which subsequently leads to Bi2O3 sublimation and a textured YBCO film which directly nucleated onto the LaAlO3 single crystal substrate. Hence, this electron microscopy study indicates that bismuth-based buffer layers systems are not suitable for implementation in coated conductors.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
DOI: 10.1016/j.actamat.2015.08.023
|
|
|
“Superspace crystallography : a key to the chemistry and properties”. Pinheiro CB, Abakumov AM, IUCrJ 2, 137 (2015). http://doi.org/10.1107/S2052252514023550
Abstract: An overview is given of the recent advances in the field of modulated molecular and inorganic crystals with an emphasis on the links between incommensurability, intermolecular and interatomic interactions and, wherever possible, the properties of the materials. The importance of detailed knowledge on the modulated structure for understanding the crystal chemistry and the functional properties of modulated phases is shown using selected examples of incommensurate modulations in organic molecular compounds and inorganic complex oxides.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 5.793
Times cited: 15
DOI: 10.1107/S2052252514023550
|
|
|
“Synergy between transmission electron microscopy and powder diffraction : application to modulated structures”. Batuk D, Batuk M, Abakumov AM, Hadermann J, Acta crystallographica: section B: structural science 71, 127 (2015). http://doi.org/10.1107/S2052520615005466
Abstract: The crystal structure solution of modulated compounds is often very challenging, even using the well established methodology of single-crystal X-ray crystallography. This task becomes even more difficult for materials that cannot be prepared in a single-crystal form, so that only polycrystalline powders are available. This paper illustrates that the combined application of transmission electron microscopy (TEM) and powder diffraction is a possible solution to the problem. Using examples of anion-deficient perovskites modulated by periodic crystallographic shear planes, it is demonstrated what kind of local structural information can be obtained using various TEM techniques and how this information can be implemented in the crystal structure refinement against the powder diffraction data. The following TEM methods are discussed: electron diffraction (selected area electron diffraction, precession electron diffraction), imaging (conventional high-resolution TEM imaging, high-angle annular dark-field and annular bright-field scanning transmission electron microscopy) and state-of-the-art spectroscopic techniques (atomic resolution mapping using energy-dispersive X-ray analysis and electron energy loss spectroscopy).
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.032
Times cited: 11
DOI: 10.1107/S2052520615005466
|
|
|
“Novel 3DOM BiVO4/TiO2nanocomposites for highly enhanced photocatalytic activity”. Zalfani M, van der Schueren B, Hu Z-Y, Rooke JC, Bourguiga R, Wu M, Li Y, Van Tendeloo G, Su B-L, Journal of materials chemistry A : materials for energy and sustainability 3, 21244 (2015). http://doi.org/10.1039/C5TA00783F
Abstract: Novel 3DOM BiVO4/TiO2 nanocomposites with intimate contact were for the first time synthesized by a hydrothermal method in order to elucidate their visible-light-driven photocatalytic performances. BiVO4 nanoparticles and 3DOM TiO2 inverse opal were fabricated respectively. These materials were characterized by XRD, XPS, SEM, TEM, N2 adsorption–desorption and UV-vis diffuse (UV-vis) and photoluminescence spectroscopies. As references for comparison, a physical mixture of BiVO4 nanoparticles and 3DOM TiO2 inverse opal powder (0.08 : 1), and a BiVO4/P25 TiO2 (0.08 : 1) nanocomposite made also by the hydrothermal method were prepared. The photocatalytic performance of all the prepared materials was evaluated by the degradation of rhodamine B (RhB) as a model pollutant molecule under visible light irradiation. The highly ordered 3D macroporous inverse opal structure can provide more active surface areas and increased mass transfer because of its highly accessible 3D porosity. The results show that 3DOM BiVO4/TiO2 nanocomposites possess a highly prolonged lifetime and increased separation of visible light generated charges and extraordinarily high photocatalytic activity. Owing to the intimate contact between BiVO4 and large surface area 3DOM TiO2, the photogenerated high energy charges can be easily transferred from BiVO4 to the 3DOM TiO2 support. BiVO4 nanoparticles in the 3DOM TiO2 inverse opal structure act thus as a sensitizer to absorb visible light and to transfer efficiently high energy electrons to TiO2 to ensure long lifetime of the photogenerated charges and keep them well separated, owing to the direct band gap of BiVO4 of 2.4 eV, favourably positioned band edges, very low recombination rate of electron–hole pairs and stability when coupled with photocatalysts, explaining the extraordinarily high photocatalytic performance of 3DOM BiVO4/TiO2 nanocomposites. It is found that larger the amount of BiVO4 in the nanocomposite, longer the duration of photogenerated charge separation and higher the photocatalytic activity. This work can shed light on the development of novel visible light responsive nanomaterials for efficient solar energy utilisation by the intimate combination of an inorganic light sensitizing nanoparticle with an inverse opal structure with high diffusion efficiency and high accessible surface area.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 8.867
Times cited: 88
DOI: 10.1039/C5TA00783F
|
|
|
“3D Magnetic Induction Maps of Nanoscale Materials Revealed by Electron Holographic Tomography”. Wolf D, Rodriguez LA, Béché, A, Javon E, Serrano L, Magen C, Gatel C, Lubk A, Lichte H, Bals S, Van Tendeloo G, Fernández-Pacheco A, De Teresa JM, Snoeck E, Chemistry of materials 27, 6771 (2015). http://doi.org/10.1021/acs.chemmater.5b02723
Abstract: The investigation of three-dimensional (3D) ferromagnetic nanoscale materials constitutes one of the key research areas of the current magnetism roadmap, and carries great potential to impact areas such as data storage, sensing and biomagnetism. The properties of such nanostructures are closely connected with their 3D magnetic nanostructure, making their determination highly valuable. Up to now, quantitative 3D maps providing both the internal magnetic and electric configuration of the same specimen with high spatial resolution are missing. Here, we demonstrate the quantitative 3D reconstruction of the dominant axial component of the magnetic induction and electrostatic potential within a cobalt nanowire (NW) of 100 nm in diameter with spatial resolution below 10 nanometers by applying electron holographic tomography. The tomogram was obtained using a dedicated TEM sample holder for acquisition, in combination with advanced alignment and tomographic reconstruction routines. The powerful approach presented here is widely applicable to a broad range of 3D magnetic nanostructures and may trigger the progress of novel spintronic non-planar nanodevices.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 50
DOI: 10.1021/acs.chemmater.5b02723
|
|
|
“Fe2O3-TiO2 nanosystems by a hybrid PE-CVD/ALD approach : controllable synthesis, growth mechanism, and photocatalytic properties”. Barreca D, Carraro G, Warwick MEA, Kaunisto K, Gasparotto A, Gombac V, Sada C, Turner S, Van Tendeloo G, Maccato C, Fornasiero P;, CrystEngComm 17, 6219 (2015). http://doi.org/10.1039/c5ce00883b
Abstract: Supported Fe2O3–TiO2 nanocomposites are fabricated by an original vapor phase synthetic strategy, consisting of the initial growth of Fe2O3 nanosystems on fluorine-doped tin oxide substrates by plasma enhanced-chemical vapor deposition, followed by atomic layer deposition of TiO2 overlayers with variable thickness, and final thermal treatment in air. A thorough characterization of the target systems is carried out by X-ray diffraction, atomic force microscopy, field emission-scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. High purity nanomaterials characterized by the co-presence of Fe2O3 (hematite) and TiO2 (anatase), with an intimate Fe2O3–TiO2 contact, are successfully obtained. In addition, photocatalytic tests demonstrate that, whereas both single-phase oxides do not show appreciable activity, the composite systems are able to degrade methyl orange aqueous solutions under simulated solar light, and even visible light, with an efficiency directly dependent on TiO2 overlayer thickness. This finding opens attractive perspectives for eventual applications in wastewater treatment.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.474
Times cited: 25
DOI: 10.1039/c5ce00883b
|
|
|
“KEu(MoO4)2 : polymorphism, structures, and luminescent properties”. Morozov VA, Arakcheeva AV, Pattison P, Meert KW, Smet PF, Poelman D, Gauquelin N, Verbeeck J, Abakumov AM, Hadermann J, Chemistry of materials 27, 5519 (2015). http://doi.org/10.1021/acs.chemmater.5b01622
Abstract: In this paper, with the example of two different polymorphs of KEu(MoO4)2, the influence of the ordering of the A-cations on the luminescent properties in scheelite related compounds (A′,A″)n[(B′,B″)O4]m is investigated. The polymorphs were synthesized using a solid state method. The study confirmed the existence of only two polymorphic forms at annealing temperature range 9231203 K and ambient pressure: a low temperature anorthic α-phase and a monoclinic high temperature β-phase with an incommensurately modulated structure. The structures of both polymorphs were solved using transmission electron microscopy and refined from synchrotron powder X-ray diffraction data. The monoclinic β-KEu(MoO4)2 has a (3+1)-dimensional incommensurately modulated structure (superspace group I2/b(αβ0)00, a = 5.52645(4) Å, b = 5.28277(4) Å, c = 11.73797(8) Å, γ = 91.2189(4)o, q = 0.56821(2)a*0.12388(3)b*), whereas the anorthic α-phase is (3+1)-dimensional commensurately modulated (superspace group I1̅(αβγ)0, a = 5.58727(22) Å, b = 5.29188(18)Å, c = 11.7120(4) Å, α = 90.485(3)o, β = 88.074(3)o, γ = 91.0270(23)o, q = 1/2a* + 1/2c*). In both cases the modulation arises due to Eu/K cation ordering at the A site: the formation of a 2-dimensional Eu3+ network is characteristic for the α-phase, while a 3-dimensional Eu3+-framework is observed for the β-phase structure. The luminescent properties of KEu(MoO4)2 samples prepared under different annealing conditions were measured, and the relation between their optical properties and their structures is discussed.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 26
DOI: 10.1021/acs.chemmater.5b01622
|
|
|
“Li2Cu2O(SO4)2: a possible electrode for sustainable Li-based batteries showing a 4.7 V redox activity vs Li+/Li0”. Sun M, Rousse G, Abakumov AM, Saubanere M, Doublet M-L, Rodriguez-Carvajal J, Van Tendeloo G, Tarascon J-M, Chemistry of materials 27, 3077 (2015). http://doi.org/10.1021/acs.chemmater.5b00588
Abstract: Li-ion batteries rely on the use of insertion positive electrodes with performances scaling with the redox potential of the 31) metals accompanying Liuptake/removal. Although not commonly studied, the Cu2+/Cu3+ redox potential has been predicted from theoretical calculations to possibly offer a high operating voltage redox couple. We herein report the synthesis and crystal structure of a hitherto-unknown oxysulfate phase, Li2Cu2O(SO4)(2), which contains infinite edgesharing CuO4 chains and presents attractive electrochemical redox activity with respect to Li+/Li, namely amphoteric characteristics. Li2Cu2O(SO4)(2) shows redox activity at 4.7 V vs Li+/Li corresponding to the oxidation of Cu2+ to Cu3+ enlisting ligand holes and associated with the reversible uptake-removal of 0.3 Li. Upon reduction, this compound reversibly uptakes similar to 2 Li at an average potential of about 2.5 V vs Li+/Li, associated with the Cu2+/Cu+ redox couple. The mechanism of the reactivity upon reduction is discussed in detail, with particular attention to the occasional appearance of an oscillation wave in the discharge profile. Our work demonstrates that Cu-based compounds can indeed be fertile scientific ground in the search for new high-energy-density electrodes.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 20
DOI: 10.1021/acs.chemmater.5b00588
|
|
|
“Mn2FeWO6 : a new Ni3TeO6-type polar and magnetic oxide”. Li MR, Croft M, Stephens PW, Ye M, Vanderbilt D, Retuerto M, Deng Z, Grams CP, Hemberger J, Hadermann J, Li WM, Jin CQ, Saouma FO, Jang JI, Akamatsu H, Gopalan V, Walker D, Greenblatt M;, Advanced materials 27, 2177 (2015). http://doi.org/10.1002/adma.201405244
Abstract: Mn22+Fe2+W6+O6, a new polar magnetic phase, adopts the corundum-derived Ni3TeO6-type structure with large spontaneous polarization (P-S) of 67.8 mu C cm-2, complex antiferromagnetic order below approximate to 75 K, and field-induced first-order transition to a ferrimagnetic phase below approximate to 30 K. First-principles calculations predict a ferrimagnetic (udu) ground state, optimal switching path along the c-axis, and transition to a lower energy udu-udd magnetic double cell.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 19.791
Times cited: 32
DOI: 10.1002/adma.201405244
|
|
|
“Co-Rich ZnCoO Nanoparticles Embedded in Wurtzite Zn1-xCoxO Thin Films: Possible Origin of Superconductivity”. Zeng Y-J, Gauquelin N, Li D-Y, Ruan S-C, He H-P, Egoavil R, Ye Z-Z, Verbeeck J, Hadermann J, Van Bael MJ, Van Haesendonck C, ACS applied materials and interfaces 7, 22166 (2015). http://doi.org/10.1021/acsami.5b06363
Abstract: Co-rich ZnCoO nanoparticles embedded in wurtzite Zn0.7Co0.3O thin films are grown by pulsed laser deposition on a Si substrate. Local superconductivity with an onset Tc at 5.9 K is demonstrated in the hybrid system. The unexpected superconductivity probably results from Co(3+) in the Co-rich ZnCoO nanoparticles or from the interface between the Co-rich nanoparticles and the Zn0.7Co0.3O matrix.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 7.504
Times cited: 13
DOI: 10.1021/acsami.5b06363
|
|
|
“The role of the VZn-NO-H complex in the p-type conductivity in ZnO”. Amini MN, Saniz R, Lamoen D, Partoens B, Physical chemistry, chemical physics 17, 5485 (2015). http://doi.org/10.1039/c4cp05894a
Abstract: Past research efforts aiming at obtaining stable p-type ZnO have been based on complexes involving nitrogen doping. A recent experiment by (J. G. Reynolds et al., Appl. Phys. Lett., 2013, 102, 152114) demonstrated a significant ([similar]1018 cm−3) p-type behavior in N-doped ZnO films after appropriate annealing. The p-type conductivity was attributed to a VZnNOH shallow acceptor complex, formed by a Zn vacancy (VZn), N substituting O (NO), and H interstitial (Hi). We present here a first-principles hybrid functional study of this complex compared to the one without hydrogen. Our results confirm that the VZnNOH complex acts as an acceptor in ZnO. We find that H plays an important role, because it lowers the formation energy of the complex with respect to VZnNO, a complex known to exhibit (unstable) p-type behavior. However, this additional H atom also occupies the hole level at the origin of the shallow behavior of VZnNO, leaving only two states empty higher in the band gap and making the VZnNOH complex a deep acceptor. Therefore, we conclude that the cause of the observed p-type conductivity in experiment is not the presence of the VZnNOH complex, but probably the formation of the VZnNO complex during the annealing process.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Impact Factor: 4.123
Times cited: 20
DOI: 10.1039/c4cp05894a
|
|
|
“Thermal conductivity of titanium nitride/titanium aluminum nitride multilayer coatings deposited by lateral rotating cathode arc”. Samani MK, Ding XZ, Khosravian N, Amin-Ahmadi B, Yi Y, Chen G, Neyts EC, Bogaerts A, Tay BK, Thin solid films : an international journal on the science and technology of thin and thick films 578, 133 (2015). http://doi.org/10.1016/j.tsf.2015.02.032
Abstract: A seriesof [TiN/TiAlN]nmultilayer coatingswith different bilayer numbers n=5, 10, 25, 50, and 100 were deposited on stainless steel substrate AISI 304 by a lateral rotating cathode arc technique in a flowing nitrogen atmosphere. The composition and microstructure of the coatings have been analyzed by using energy dispersive X-ray spectroscopy, X-ray diffraction (XRD), and conventional and high-resolution transmission electron microscopy (HRTEM). XRD analysis shows that the preferential orientation growth along the (111) direction is reduced in the multilayer coatings. TEM analysis reveals that the grain size of the coatings decreases with increasing bilayer number. HRTEMimaging of the multilayer coatings shows a high density misfit dislocation between the TiN and TiAlN layers. The cross-plane thermal conductivity of the coatings was measured by a pulsed photothermal reflectance technique. With increasing bilayer number, the multilayer coatings' thermal conductivity decreases gradually. This reduction of thermal conductivity can be ascribed to increased phonon scattering due to the disruption of columnar structure, reduced preferential orientation, decreased grain size of the coatings and present misfit dislocations at the interfaces.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 1.879
Times cited: 41
DOI: 10.1016/j.tsf.2015.02.032
|
|
|
“Near-Infrared Emitting CuInSe/CuInS Dot Core/Rod Shell Heteronanorods by Sequential Cation Exchange”. van der Stam W, Bladt E, Rabouw FT, Bals S, de Mello Donega C, ACS nano 9, 11430 (2015). http://doi.org/10.1021/acsnano.5b05496
Abstract: The direct synthesis of heteronanocrystals (HNCs) combining different ternary semiconductors is challenging and has not yet been successful. Here, we report a sequential topotactic cation exchange (CE) pathway that yields CuInSe2/CuInS2 dot core/rod shell nanorods with near-infrared luminescence. In our approach, the Cu+ extraction rate is coupled to the In3+ incorporation rate by the use of a stoichiometric trioctylphosphine-InCl3 complex, which fulfills the roles of both In-source and Cu-extracting agent. In this way, Cu+ ions can be extracted by trioctylphosphine ligands only when the In-P bond is broken. This results in readily available In3+ ions at the same surface site from which the Cu+ is extracted, making the process a direct place exchange reaction and shifting the overall energy balance in favor of the CE. Consequently, controlled cation exchange can occur even in large and anisotropic heterostructured nanocrystals with preservation of the size, shape, and heterostructuring of the template NCs into the product NCs. The cation exchange is self-limited, stopping when the ternary core/shell CuInSe2/CuInS2 composition is reached. The method is very versatile, successfully yielding a variety of luminescent CuInX2 (X = S, Se, and Te) quantum dots, nanorods, and HNCs, by using Cd-chalcogenide NCs and HNCs as templates. The approach reported here thus opens up routes toward materials with unprecedented properties, which would otherwise remain inaccessible.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 88
DOI: 10.1021/acsnano.5b05496
|
|
|
“Tuning metal sites of DABCO MOF for gas purification at ambient conditions”. Chemchuen S, Zhou K, Kabir NA, Chen Y, Ke X, Van Tendeloo G, Verpoort F, Microporous and mesoporous materials: zeolites, clays, carbons and related materials 201, 277 (2015). http://doi.org/10.1016/j.micromeso.2014.09.038
Abstract: Metalorganic frameworks (MOFs) have emerged as new porous materials for capture and separation of binary gas mixtures. Tuning the metal sites in MOF structures has an impact on properties, which enhance affinity of gas adsorption and selectivity (e.g., surface area, cavity, electric field, etc.). The synthesis and characterization of a M-DABCO series (M = Ni, Co, Cu, Zn) of MOFs are described in this study. The experiments were conducted using multicomponent gas mixtures and the Ideal Adsorbed Solution Theory (IAST) was applied to determine the CO2/CH4 selectivity. Experimental adsorption isotherms were fitted with a model equation to evaluate the characteristic adsorption energy (Isosteric, Qst) of this series. The Ni metal in the M-DABCO series reveals the best performance concerning CO2 adsorption and CH4/CO2 selectivity at ambient conditions based on IAST calculations. The combination of characterizations, calculations and adsorption experiments were used to discuss the metal impact on the adsorption sites in the M-DABCO series at ambient conditions.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.615
Times cited: 38
DOI: 10.1016/j.micromeso.2014.09.038
|
|
|
“Understanding the roles of anionic redox and oxygen release during electrochemical cycling of lithium-rich layered Li4FeSbO6”. McCalla E, Sougrati MT, Rousse G, Berg EJ, Abakumov A, Recham N, Ramesha K, Sathiya M, Dominko R, Van Tendeloo G, Novák P, Tarascon JM;, Journal of the American Chemical Society 137, 4804 (2015). http://doi.org/10.1021/jacs.5b01424
Abstract: Li-rich oxides continue to be of immense interest as potential next generation Li-ion battery positive electrodes, and yet the role of oxygen during cycling is still poorly understood. Here, the complex electrochemical behavior of Li4FeSbO6 materials is studied thoroughly with a variety of methods. Herein, we show that oxygen release occurs at a distinct voltage plateau from the peroxo/superoxo formation making this material ideal for revealing new aspects of oxygen redox processes in Li-rich oxides. Moreover, we directly demonstrate the limited reversibility of the oxygenated species (O-2(n-); n = 1, 2, 3) for the first time. We also find that during charge to 4.2 V iron is oxidized from +3 to an unusual +4 state with the concomitant formation of oxygenated species. Upon further charge to 5.0 V, an oxygen release process associated with the reduction of iron +4 to +3 is present, indicative of the reductive coupling mechanism between oxygen and metals previously reported. Thus, in full state of charge, lithium removal is fully compensated by oxygen only, as the iron and antimony are both very close to their pristine states. Besides, this charging step results in complex phase transformations that are ultimately destructive to the crystallinity of the material. Such findings again demonstrate the vital importance of fully understanding the behavior of oxygen in such systems. The consequences of these new aspects of the electrochemical behavior of lithium-rich oxides are discussed in detail.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 13.858
Times cited: 86
DOI: 10.1021/jacs.5b01424
|
|
|
“The uptake and elimination of ZnO and CuO nanoparticles in Daphnia magna under chronic exposure scenarios”. Adam N, Leroux F, Knapen D, Bals S, Blust R, Water research 68, 249 (2015). http://doi.org/10.1016/j.watres.2014.10.001
Abstract: In this study, the uptake and elimination of ZnO and CuO nanoparticles in Daphnia magna was tested. Daphnids were exposed during 10 days to sublethal concentrations of ZnO and CuO nanoparticles and corresponding metal salts (ZnCl2 and CuCl2.2H2O), after which they were transferred to unexposed medium for another 10 days. At different times during the exposure and none-exposure, the total and internal zinc or copper concentration of the daphnids was determined and the nanoparticles were localized in the organism using electron microscopy. The exposure concentrations were characterized by measuring the dissolved, nanoparticle and aggregated fraction in the medium. The results showed that the ZnO nanoparticles quickly dissolved after addition to the medium. Contrarily, only a small fraction (corresponding to the dissolved metal salt) of the CuO nanoparticles dissolved, while most of these nanoparticles formed large aggregates. Despite an initial increase in zinc and copper concentration during the first 48 hour to 5 day exposure, the body concentration reached a plateau level that was comparable for the ZnO nanoparticles and ZnCl2, but much higher for the CuO nanoparticles (with visible aggregates accumulating in the gut) than CuCl2.2H2O. During the remaining exposure and subsequent none-exposure phase, the zinc and copper concentration decreased fast to concentrations comparable with the unexposed daphnids. The results indicate that D. magna can regulate its internal zinc and copper concentration after exposure to ZnO and CuO nanoparticles, similar as after exposure to metal salts. The combined dissolution, accumulation and toxicity results confirm that the toxicity of ZnO and CuO nanoparticles is caused by the dissolved fraction. Keywords nano; zinc; copper; dissolution; aggregation; electron microscopy
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Veterinary physiology and biochemistry
Impact Factor: 6.942
Times cited: 51
DOI: 10.1016/j.watres.2014.10.001
|
|
|
“Using electron vortex beams to determine chirality of crystals in transmission electron microscopy”. Juchtmans R, Béché, A, Abakumov A, Batuk M, Verbeeck J, Physical review : B : condensed matter and materials physics 91, 094112 (2015). http://doi.org/10.1103/PhysRevB.91.094112
Abstract: We investigate electron vortex beams elastically scattered on chiral crystals. After deriving a general expression for the scattering amplitude of a vortex electron, we study its diffraction on point scatterers arranged on a helix. We derive a relation between the handedness of the helix and the topological charge of the electron vortex on one hand and the symmetry of the higher-order Laue zones in the diffraction pattern on the other for kinematically and dynamically scattered electrons. We then extend this to atoms arranged on a helix as found in crystals which belong to chiral space groups and propose a method to determine the handedness of such crystals by looking at the symmetry of the diffraction pattern. In contrast to alternative methods, our technique does not require multiple scattering, which makes it possible to also investigate extremely thin samples in which multiple scattering is suppressed. In order to verify the model, elastic scattering simulations are performed, and an experimental demonstration on Mn2Sb2O7 is given in which we find the sample to belong to the right-handed variant of its enantiomorphic pair. This demonstrates the usefulness of electron vortex beams to reveal the chirality of crystals in a transmission electron microscope and provides the required theoretical basis for further developments in this field.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 54
DOI: 10.1103/PhysRevB.91.094112
|
|
|
“Vapor phase processing of \alpha-Fe2O3 photoelectrodes for water splitting : an insight into the structure/property interplay”. Warwick MEA, Kaunisto K, Barreca D, Carraro G, Gasparotto A, Maccato C, Bontempi E, Sada C, Ruoko TP, Turner S, Van Tendeloo G;, ACS applied materials and interfaces 7, 8667 (2015). http://doi.org/10.1021/acsami.5b00919
Abstract: Harvesting radiant energy to trigger water photoelectrolysis and produce clean hydrogen is receiving increasing attention in the search of alternative energy resources. In this regard, hematite (alpha-Fe2O3) nanostructures with controlled nano-organization have been fabricated and investigated for use as anodes in photoelectrochemical (PEC) cells. The target systems have been grown on conductive substrates by plasma enhanced-chemical vapor deposition (PE-CVD) and subjected to eventual ex situ annealing in air to further tailor their structure and properties. A detailed multitechnique approach has enabled to elucidate between system characteristics and the generated photocurrent. The present alpha-Fe2O3 systems are characterized by a high purity and hierarchical morphologies consisting of nanopyramids/organized dendrites, offering a high contact area with the electrolyte. PEC data reveal a dramatic response enhancement upon thermal treatment, related to a more efficient electron transfer. The reasons underlying such a phenomenon are elucidated and discussed by transient absorption spectroscopy (TAS) studies of photogenerated charge carrier kinetics, investigated on different time scales for the first time on PE-CVD Fe2O3 nanostructures.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 7.504
Times cited: 51
DOI: 10.1021/acsami.5b00919
|
|
|
“VEGF-targeted magnetic nanoparticles for MRI visualization of brain tumor”. Abakumov MA, Nukolova NV, Sokolsky-Papkov M, Shein SA, Sandalova TO, Vishwasrao HM, Grinenko NF, Gubsky IL, Abakumov AM, Kabanov AV, Chekhonin VP;, Nanomedicine: nanotechnology, biology and medicine 11, 825 (2015). http://doi.org/10.1016/j.nano.2014.12.011
Abstract: This work is focused on synthesis and characterization of targeted magnetic nanoparticles as magnetic resonance imaging (MRI) agents for in vivo visualization of gliomas. Ferric oxide (Fe3O4) cores were synthesized by thermal decomposition and coated with bovine serum albumin (BSA) to form nanoparticles with D-eff of 53 +/- 9 nm. The BSA was further cross-linked to improve colloidal stability. Monoclonal antibodies against vascular endothelial growth factor (mAbVEGF) were covalently conjugated to BSA through a polyethyleneglycol linker. Here we demonstrate that 1) BSA coated nanoparticles are stable and non-toxic to different cells at concentration up to 2.5 mg/mL; 2) conjugation of monoclonal antibodies to nanoparticles promotes their binding to VEGF-positive glioma C6 cells in vitro; 3) targeted nanoparticles are effective in MRI visualization of the intracranial glioma. Thus, mAbVEGF-targeted BSA-coated magnetic nanoparticles are promising MRI contrast agents for glioma visualization. (C) 2015 Elsevier Inc. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.72
Times cited: 62
DOI: 10.1016/j.nano.2014.12.011
|
|
|
“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
|
|
|
“BaHfO3artificial pinning centres in TFA-MOD-derived YBCO and GdBCO thin films”. Erbe M, Hänisch J, Hühne R, Freudenberg T, Kirchner A, Molina-Luna L, Damm C, Van Tendeloo G, Kaskel S, Schultz L, Holzapfel B, Superconductor science and technology 28, 114002 (2015). http://doi.org/10.1088/0953-2048/28/11/114002
Abstract: Chemical solution deposition (CSD) is a promising way to realize REBa2Cu3O7−x (REBCO;RE = rare earth (here Y, Gd))-coated conductors with high performance in applied magnetic fields. However, the preparation process contains numerous parameters which need to be tuned to achieve high-quality films. Therefore, we investigated the growth of REBCO thin films containing nanometre-scale BaHfO3 (BHO) particles as pinning centres for magnetic flux lines, with emphasis on the influence of crystallization temperature and substrate on the microstructure and superconductivity. Conductivity, microscopy and x-ray investigations show an enhanced performance of BHO nano-composites in comparison to pristine REBCO. Further, those measurements reveal the superiority of GdBCO to YBCO—e.g. by inductive critical current densities, Jc, at self-field and 77 K. YBCO is outperformed by more than 1 MA cm−2 with Jc values of up to 5.0 MA cm−2 for 265 nm thick layers of GdBCO(BHO) on lanthanum aluminate. Transport in-field Jc measurements demonstrate high pinning force maxima of around 4 GN m−3 for YBCO(BHO) and GdBCO(BHO). However, the irreversibility fields are appreciably higher for GdBCO. The critical temperature was not significantly reduced upon BHO addition to both YBCO and GdBCO, indicating a low tendency for Hf diffusion into the REBCO matrix. Angular-dependent Jc measurements show a reduction of the anisotropy in the same order of magnitude for both REBCO compounds. Theoretical models suggest that more than one sort of pinning centre is active in all CSD films.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.878
Times cited: 36
DOI: 10.1088/0953-2048/28/11/114002
|
|
|
“The ASTRA Toolbox: A platform for advanced algorithm development in electron tomography”. van Aarle W, Palenstijn WJ, De Beenhouwer J, Altantzis T, Bals S, Batenburg KJ, Sijbers J, Ultramicroscopy 157, 35 (2015). http://doi.org/10.1016/j.ultramic.2015.05.002
Abstract: We present the ASTRA Toolbox as an open platform for 3D image reconstruction in tomography. Most of the software tools that are currently used in electron tomography offer limited flexibility with respect to the geometrical parameters of the acquisition model and the algorithms used for reconstruction. The ASTRA Toolbox provides an extensive set of fast and flexible building blocks that can be used to develop advanced reconstruction algorithms, effectively removing these limitations. We demonstrate this flexibility, the resulting reconstruction quality, and the computational efficiency of this toolbox by a series of experiments, based on experimental dual-axis tilt series.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 2.843
Times cited: 562
DOI: 10.1016/j.ultramic.2015.05.002
|
|
|
“Controlled Living Nanowire Growth: Precise Control over the Morphology and Optical Properties of AgAuAg Bimetallic Nanowires”. Mayer M, Scarabelli L, March K, Altantzis T, Tebbe M, Kociak M, Bals S, Garcia de Abajo FJ, Fery A, Liz-Marzan LM, Nano letters 15, 5427 (2015). http://doi.org/10.1021/acs.nanolett.5b01833
Abstract: Inspired by the concept of living polymerization reaction, we are able to produce silver-gold-silver nanowires with a precise control over their total length and plasmonic properties by establishing a constant silver deposition rate on the tips of penta-twinned gold nanorods used as seed cores. Consequently, the length of the wires increases linearly in time. Starting with approximately 210 nm x 32 nm gold cores, we produce nanowire lengths up to several microns in a highly controlled manner, with a small self-limited increase in thickness of approximately 4 nm, corresponding to aspect ratios above 100, whereas the low polydispersity of the product allows us to detect up to nine distinguishable plasmonic resonances in a single colloidal solution. We analyze the spatial distribution and the nature of the plasmons by electron energy loss spectroscopy and obtain excellent agreement between measurements and electromagnetic simulations, clearly demonstrating that the presence of the gold core plays a marginal role, except for relatively short wires or high-energy modes.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 12.712
Times cited: 117
DOI: 10.1021/acs.nanolett.5b01833
|
|
|
“Femtosecond Laser-Controlled Tip-to-Tip Assembly and Welding of Gold Nanorods”. Gonzalez-Rubio G, Gonzalez-Izquierdo J, Banares L, Tardajos G, Rivera A, Altantzis T, Bals S, Pena-Rodriguez O, Guerrero-Martinez A, Liz-Marzan LM, Nano letters 15, 8282 (2015). http://doi.org/10.1021/acs.nanolett.5b03844
Abstract: Directed assembly of gold nanorods through the use of dithiolated molecular linkers is one of the most efficient methodologies for the morphologically controlled tip-to-tip assembly of this type of anisotropic nanocrystals. However, in a direct analogy to molecular polymerization synthesis, this process is characterized by difficulties in chain-growth control over nanoparticle oligomers. In particular, it is nearly impossible to favor the formation of one type of oligomer, making the methodology hard to use for actual applications in nanoplasmonics. We propose here a light-controlled synthetic procedure that allows obtaining selected plasmonic oligomers in high yield and with reaction times in the scale of minutes by irradiation with low fluence near-infrared (NIR) femtosecond laser pulses. Selective inhibition of the formation of gold nanorod n-mers (trimers) with a longitudinal localized surface plasmon in resonance with a 800 nm Ti:sapphire laser, allowed efficient trapping of the (n – 1)-mers (dimers) by hot spot mediated photothermal decomposition of the interparticle molecular linkers. Laser irradiation at higher energies produced near-field enhancement at the interparticle gaps, which is large enough to melt gold nanorod tips, offering a new pathway toward tip-to-tip welding of gold nanorod oligomers with a plasmonic response at the NIR. Thorough optical and electron microscopy characterization indicates that plasmonic oligomers can be selectively trapped and welded, which has been analyzed in terms of a model that predicts with reasonable accuracy the relative concentrations of the main plasmonic species.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.712
Times cited: 101
DOI: 10.1021/acs.nanolett.5b03844
|
|
|
“Collective Plasmonic Properties in Few-Layer Gold Nanorod Supercrystals”. Hamon C, Novikov SM, Scarabelli L, Solís DM, Altantzis T, Bals S, Taboada JM, Obelleiro F, Liz-Marzán LM, ACS Photonics 2, 1482 (2015). http://doi.org/10.1021/acsphotonics.5b00369
Abstract: Gold nanorod supercrystals have been widely employed for the detection of relevant bioanalytes with detection limits ranging from nano- to picomolar levels,
confirming the promising nature of these structures for biosensing. Even though a relationship between the height of the supercrystal (i.e., the number of stacked nanorod layers)and the enhancement factor has been proposed, no systematic
study has been reported. In order to tackle this problem, we prepared gold nanorod supercrystals with varying numbers of stacked layers and analyzed them extensively by atomic force microscopy, electron microscopy and surface enhanced Raman scattering. The experimental results were compared to numerical
simulations performed on real-size supercrystals composed of thousands of nanorod building blocks. Analysis of the hot spot distribution in the simulated supercrystals showed the presence of standing waves that were distributed at different depths, depending on the number of layers in each supercrystal. On the basis of these theoretical results, we interpreted the experimental
data in terms of analyte penetration into the topmost layer only, which indicates that diffusion to the interior of the supercrystals would be crucial if the complete field enhancement produced by the stacked nanorods is to be exploited. We propose that our conclusions will be of high relevance in the design of next generation plasmonic devices.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 6.756
Times cited: 70
DOI: 10.1021/acsphotonics.5b00369
|
|
|
“Optimization of Automated Crystal Orientation and Phase Mapping in TEM Applied to Ni-Ti All Round Shape Memory Alloy”. Yao X, Li Y, Cao S, Ma X, Zhang X-ping, Schryvers D, MATEC web of conferences
T2 –, Proceedings of ESOMAT 2015 10th European Symposium on Martensitic Transformations, September 14-18, 2015, Antwerp, Belgium 33, 03022 (2015). http://doi.org/10.1051/matecconf/20153303022
Abstract: A new application which focuses on an artificial sphincter fabricated by Ni-Ti SMAs for human implantation is under investigation by applying the all-round shape memory effect with precise control of the phase transformation temperatures. In this study, a Ni51at.%-Ti alloy was fabricated by arc melting with fast solidification, followed by a proper strained aging which induces the two way shape memory effect needed for this particular application. Differential scanning calorimetry was used to investigate the thermal behavior and transmission electron microscopy was used for studying the microstructure of the alloys. With the latter the novel technique of automated crystal orientation microscopy is used and optimized to obtain phase and orientation mapping of the various structures.
Keywords: P1 Proceeding; Electron microscopy for materials research (EMAT)
Times cited: 1
DOI: 10.1051/matecconf/20153303022
|
|
|
“Microstructural Characterization and Transformation Behavior of Porous Ni50.8Ti49.2”. Yao X, Cao S, Zhang XP, Schryvers D, Materials Today: Proceedings 2, S833 (2015). http://doi.org/10.1016/j.matpr.2015.07.411
Abstract: Porous Ni50.8Ti49.2 bulk material was prepared by powder metallurgy sintering. Solid solution and aging treatments were applied to improve the phase homogeneity and phase transformation behavior. Scanning and transmission electron microscopy, aided by energy dispersive X-ray analysis, were used to study the microstructure and chemical phase content of the alloys. In-situ cooling was carried out to observe the phase transformation behavior. As-received material contains dispersed Ni2Ti4O particles while Ni4Ti3 precipitates appear after aging. Close to pore edges, the latter have a preferential orientation due to the induced stress fields in the matrix.
Keywords: P1 Proceeding; Electron microscopy for materials research (EMAT)
DOI: 10.1016/j.matpr.2015.07.411
|
|
|
“A quantitative method to characterize the Al4C3-formed interfacial reaction: the case study of MWCNT/Al composites”. Yan L, Tan Z, Ji G, Li Z, Fan G, Schryvers D, Shan A, Zhang D, Materials characterization 112, 213 (2015). http://doi.org/10.1016/j.matchar.2015.12.031
Abstract: The Al4C3-formed interfacial reaction plays an important role in tuning the mechanical and thermal properties of carbon/aluminum (C/Al) composites reinforced with carbonaceous materials such as multi-wall carbon nanotube (MWCNT) and graphene nanosheet. In terms of the hydrolysis nature of Al4C3, an electrochemical dissolution method was developed to quantitatively characterize the extent of C/Al interfacial reaction, which involves dissolving the composite samples in alkaline solution first, then collecting and measuring the CH4 gas released by Al4C3 hydrolysis with a gas chromatograph. Through a case study with powder metallurgy fabricated 2.0 wt.% MWCNT/Al composites, the detectability limit of the proposed method is 0.4 wt.% Al4C3, corresponding to 5 % extent of interfacial reaction with a measurement error of ±3 %. And then, with the already known MWCNT/Al reaction extent vs different sintering temperature and time, the reaction kinetics with an activation energy of 281 kJ mol-1 was successfully derived. Therefore, this rapid, sensitive, accurate method supplies an useful tool to optimize the processing and properties of all kinds of C/Al composites via interface design/control.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 2.714
Times cited: 24
DOI: 10.1016/j.matchar.2015.12.031
|
|