Khalilov U (2013) New perspectives on thermal and hyperthermal oxidation of Si surfaces. Antwerpen
Keywords: Doctoral thesis; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
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“Small-angle X-ray scattering and light scattering study of hybrid nanoparticles composed of thermoresponsive triblock copolymer F127 and thermoresponsive statistical polyoxazolines with hydrophobic moieties”. Bogomolova A, Hruby M, Panek J, Rabyk M, Turner S, Bals S, Steinhart M, Zhigunov A, Sedlacek O, Stepanek P, Filippov SK;, Journal of applied crystallography 46, 1690 (2013). http://doi.org/10.1107/S0021889813027064
Abstract: A combination of new thermoresponsive statistical polyoxazolines, poly[(2-butyl-2-oxazoline)-stat-(2-isopropyl-2-oxazoline)] [pBuOx-co-piPrOx], with different hydrophobic moieties and F127 surfactant as a template system for the creation of thermosensitive nanoparticles for radionuclide delivery has recently been tested [Pánek, Filippov, Hrubý, Rabyk, Bogomolova, Kučka Stěpánek (2012). Macromol. Rapid Commun.33, 16831689]. It was shown that the presence of the thermosensitive F127 triblock copolymer in solution reduces nanoparticle size and polydispersity. This article focuses on a determination of the internal structure and solution properties of the nanoparticles in the temperature range from 288 to 312 K. Here, it is demonstrated that below the cloud point temperature (CPT) the polyoxazolines and F127 form complexes that co-exist in solution with single F127 molecules and large aggregates. When the temperature is raised above the CPT, nanoparticles composed of polyoxazolines and F127 are predominant in solution. These nanoparticles could be described by a spherical shell model. It was found that the molar weight and hydrophobicity of the polymer do not influence the size of the outer radius and only slightly change the inner radius of the nanoparticles. At the same time, molar weight and hydrophobicity did affect the process of nanoparticle formation. In conclusion, poly(2-oxazoline) molecules are fully incorporated inside of F127 micelles, and this result is very promising for the successful application of such systems in radionuclide delivery.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 18
DOI: 10.1107/S0021889813027064
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“Theoretical study of silicene and germanene”. Houssa M, van den Broek B, Scalise E, Pourtois G, Afanas'ev VV, Stesmans A, Graphene, Ge/iii-v, And Emerging Materials For Post Cmos Applications 5 (2013). http://doi.org/10.1149/05301.0051ECST
Abstract: The structural and electronic properties of silicene and germanene on metallic and non-metallic substrates are investigated theoretically, using first-principles simulations. We first study the interaction of silicene with Ag(111) surfaces, focusing on the (4x4) silicene/Ag structure. Due to symmetry breaking in the silicene layer (nonequivalent number of top and bottom Si atoms), silicene is predicted to be semiconducting, with a computed energy gap of about 0.3 eV. However, the charge transfer occurring at the silicene/Ag(111) interface leads to an overall metallic system. We next investigate the interaction of silicene and germanene with hexagonal non-metallic substrates, namely ZnS and ZnSe. On reconstructed (semiconducting) (0001) ZnS or ZnSe surfaces, silicene and germanene are found to be semiconducting. Remarkably, the nature (indirect or direct) and magnitude of their energy band gap can be controlled by an out-of-plane electric field.
Keywords: P1 Proceeding; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Times cited: 6
DOI: 10.1149/05301.0051ECST
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“Single-atom Catalysis Using Pt/Graphene Achieved through Atomic Layer Deposition”. Shuhui Sun Gaixia Zhang Nicolas Gauquelin Ning Chen Jigang Zhou Songlan Yang Weifeng Chen Xiangbo Meng Dongsheng Geng Mohammad N Banis Ruying Li Siyu Ye Shanna Knights Gianluigi A Botton Tsun-Kong Sham &, Xueliang Sun, Scientific Reports 3, 1775 (2013). http://doi.org/10.1038/srep01775
Abstract: Platinum-nanoparticle-based catalysts are widely used in many important chemical processes and
automobile industries. Downsizing catalyst nanoparticles to single atoms is highly desirable to maximize
their use efficiency, however, very challenging. Here we report a practical synthesis for isolated single Pt
atoms anchored to graphene nanosheet using the atomic layer deposition (ALD) technique. ALD offers the
capability of precise control of catalyst size span from single atom, subnanometer cluster to nanoparticle.
The single-atom catalysts exhibit significantly improved catalytic activity (up to 10 times) over that of the
state-of-the-art commercial Pt/C catalyst. X-ray absorption fine structure (XAFS) analyses reveal that the
low-coordination and partially unoccupied densities of states of 5d orbital of Pt atoms are responsible for the
excellent performance. This work is anticipated to form the basis for the exploration of a next generation of
highly efficient single-atom catalysts for various applications.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Times cited: 345
DOI: 10.1038/srep01775
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“Attenuation of superconductivity in manganite/cuprate heterostructures by epitaxially induced CuO intergrowths”. H Zhang N Gauquelin GA Botton and JYT Wei, Applied Physics Letters 103, 052606 (2013). http://doi.org/10.1063/1.4813840
Abstract: We examine the effect of CuO intergrowths on the superconductivity in epitaxial
La 2/3 Ca 1/3 MnO 3 / YBa 2 Cu 3 O 7−δ La2/3Ca1/3MnO3/YBa2Cu3O7−δ
(LCMO/YBCO) thin-film heterostructures. Scanning transmission electron microscopy on bilayer LCMO/YBCO thin films revealed double CuO-chain intergrowths which form regions with the 247 lattice structure in the YBCO layer. These nanoscale 247 regions do not appear in x-ray diffraction, but can physically account for the reduced critical temperature (Tc) of bilayer thin films relative to unilayer films with the same YBCO thickness, at least down to ∼25 nm. We attribute the CuO intergrowths to the bilayer heteroepitaxial mismatch and the Tc reduction to the generally lower Tc seen in bulk 247 samples. These epitaxially-induced CuO intergrowths provide a microstructural mechanism for the attenuation of superconductivity in LCMO/YBCO heterostructures.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Times cited: 12
DOI: 10.1063/1.4813840
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“Ti4O7 supported Ru@Pt core–shell catalyst for CO-tolerance in PEM fuel cell hydrogen oxidation reaction”. L Zhang J Kim J Zhang F Nan N Gauquelin GA Botton P He R Bashyam S Knights, Applied Energy 103, 507 (2013). http://doi.org/10.1016/j.apenergy.2012.10.017
Abstract: A new method is developed for synthesizing Ti4O7 supported Ru@Pt core–shell catalyst (Ru@Pt/Ti4O7) through pyrolysis followed by microwave irradiation. The purpose is to improve the Ru durability of PtRu from core–shell structure and strong bonding to Ti4O7 oxide. In this method, the first step is to co-reduce the mixture of ruthenium precursor and TiO2 in a H2 reducing atmosphere under heat-treatment to obtain a Ru core on Ti4O7 support, and the second step is to create a shell of platinum via microwave irradiation. Energy dispersive X-ray spectrometry, X-ray Diffraction, High-resolution Scanning Transmission Electron Microscopy with the high-angle annular dark-field method and Electron Energy-Loss Spectroscopy are used to demonstrate that this catalyst with larger particles has a core–shell structure with a Ru core and a Pt shell. Electrochemical measurements show Ru@Pt/Ti4O7 catalyst has a higher CO-tolerance capability than that of PtRu/C alloy catalyst.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Times cited: 33
DOI: 10.1016/j.apenergy.2012.10.017
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“Ciliary white light generated during femtosecond laser ablation on transparent dielectrics”. Liu Y, Brelet Y, He Z, Yu L, Mitryukovskiy S, Houard A, Forestier B, Couairon A, Mysyrowicz A, 2013 Conference On And International Quantum Electronics Conference Lasers And Electro-optics Europe (cleo Europe/iqec) (2013)
Keywords: P1 Proceeding; Electron microscopy for materials research (EMAT)
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“All crystal clear : 18th-century glass à, la façon de Bohème from the cistercian nunnery of Clairefontaine, Belgium”. Herremans D, Cagno S, Vincke A, Janssens K, De Clercq W, Journal of glass studies 55, 137 (2013)
Abstract: Excavations at the Cistercian nunnery of Clairefontaine, located near Arlon in the south of Belgium, revealed an assemblage of 18th-century colorless glass. The morphology of the vessels and the engraved decoration suggest a central European origin or, at least, stylistic inspiration. The composition of the glass points to a recipe combining silica, lime, and potash: a colorless potash glass a la facon de Boheme. This article considers the technology, morphology, and origin of the vessels. The art-historical analysis is supported by chemical research (scanning electron microscopy energy-dispersive X-ray spectroscopy [SEM-EDX]). The finds are also discussed in light of the emerging northwestern European glass industry, changing consumer practices during the 18th century, and their meaning for the inhabitants of the abbey.
Keywords: A1 Journal article; Art; History; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“The consolidation of cracks and fissures in dalle de verre : assessment of selected adhesives”. De Vis K, Caen J, Janssens K, Jacobs P page 43 (2013).
Abstract: Dalle de verre windows, created from 19301940 onwards, consist of glass pieces with a thickness of approximately 2 to 5 cm, set in a matrix of (reinforced) concrete. Besides the degradation of the concrete, the windows suffer mainly from a complex three-dimensional form of cracking of the glass elements. The cracks need to be consolidated in order to ensure stability and improve transparency. A selection of possible adhesives was evaluated: Araldite® 2020, Hxtal NYL-1, Fynebond, Paraloid® B-72, LV740, A18 and OR-G®. An attempt has been made to objectively compare these adhesives using a bench-marking system. None of the adhesives appears to be suitable for in situ application; sufficient penetration of the adhesives can only be realised with the help of vacuum techniques.
Keywords: H2 Book chapter; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES)
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Blust RJP, Dardenne F, De Wael K, Nagels L, Van Camp G (2013) Electrochemical aptasensors with a gelatin B matrix : EP13175128
Abstract: An aptamer-based electrochemical sensor, wherein said aptamer is covalently bonded to or chemisorbed on an electrode, said aptamer forming a robust complex with a target molecule and is encapsulated by a gelatin B matrix; a method of manufacturing an aptamer-based electrochemical sensor for determining a concentration of a target molecule comprising the steps of: selecting an aptamer to form a robust complex with a target molecule using the SELEX procedure; synthesizing said aptamer; adsorbing said aptamer on or covalently coupling said aptamer with an electrode; and providing a gelatin B matrix for said aptamer on said electrode thereby realising said aptamer-based potentiometric or amperometric sensor; and the use of the aptamer-based electrochemical sensor produced according to the above method for the electrochemical determination of a concentration of 15 the target molecule.
Keywords: Patent; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“High-resolution desktop microcomputed tomography for the evaluation of reducing treatments on historical glass suffering from manganese browning”. Nuyts G, Cagno S, Jaroszewicz J, Wouters H, De Vis K, Caen J, Janssens K page 201 (2013).
Abstract: Historical glass, especially non-durable mediaeval glass, can undergo corrosion. This sometimes results in the formation of dark-coloured manganese-rich inclusions or stains that reduce the transparency of the glass. A conservation treatment with reducing or chelating agents may be considered with the aim of improving the transparency. In this paper, high-resolution desktop microcomputed tomography (µCT) is used in combination with element-specific twodimensional imaging methods for in situ monitoring of manganese removal by hydroxylamine hydrochloride from an archaeological stained-glass sample suffering from manganese browning and from artificially corroded model glass samples. µCT also proved itself useful for the study of the (re-)penetration of manganese into the gel layer during artificial corrosion of a model glass.
Keywords: H2 Book chapter; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES)
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De Wael K, Nagels L, Van Camp G (2013) Potentiometric sensors and method for measuring intermolecular interactions
Keywords: Patent; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“Risks of atmospheric aerosol for cultural heritage assets in Granada (Spain)”. Cardell C, Urosevic M, Sebastián-Pardo E, Horemans B, Kontozova-Deutsch V, Potgieter-Vermaak S, Bencs L, Anaf KW, De Wael K, Van Grieken R page 45 (2013).
Keywords: H1 Book chapter; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
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“The stained-glass panel depicting the anointing at Bethany : art historical research, technical analysis, and treatment”. Caen J, Cagno S, Janssens K page 247 (2013).
Abstract: In 2008, Museum M in Louvain (Flanders, Belgium) acquired a panel depicting The Anointing at Bethany that is believed once to have adorned the citys former Charterhouse. The panel required conservation treatment, which was preceded by a thorough art-historical and technical examination. It emerged that comparable panels are kept at the Metropolitan Museum of Art and the Riverside Church in New York. Chemical analyses show most of the glass in the panel to have a typical 16th century high-limelow-alkali composition. The conservation treatment was based on the evaluation of these findings and focused very strongly on enhancing the aesthetic balance for an improved reading of the panel.
Keywords: H2 Book chapter; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Cultural Heritage Sciences (ARCHES)
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“Study of the early stages of Mn intrusion in corroded glass by means of combined SR FTIR/\muXRF imaging and XANES spectroscopy”. Nuyts G, Cagno S, Hellemans K, Veronesi G, Cotte M, Janssens K, Procedia Chemistry
T2 –, Youth in Conservation of Cultural Heritage Conference (YOCOCU), June 18-20, 2012, University of Antwerp, Antwerp, Belgium , 239 (2013). http://doi.org/10.1016/J.PROCHE.2013.03.030
Abstract: Historical glass, especially medieval glass, can undergo weathering under the influence of time and environmental conditions. The aim of this investigation was to better understand the processes involved in this natural degradation process by studying artificially altered glass samples prepared for the use of evaluation of conservation methods. Non-durable glass sensors produced by the Fraunhofer Institute (type M1.0) were used as a starting material for artificial alteration. These were immersed in acidic (pH = 0, 2, 4) and neutral solutions (1 h – 8 h). In a second stage the glass samples were immersed in a 0.5 M MnCl2 solution (24 h, 48 h and 72 h), allowing intrusion of Mn from the solution into the gel layer. The samples were characterized at different stages with reflectance FTIR spectroscopy, mu XRF mapping and mu XANES. All measurements were carried out at ESRF, beamline ID21. Reflectance FTIR spectroscopy measurements were performed in the 800 4000 cm(-1) range. Cluster analysis of the resulting maps evidenced the rapid growth of the gel layer in strong acidic conditions. The average spectra for each cluster feature show for the original glass a strong Si-O- stretching band between 900 and 1000 cm(-1), whereas the gel layer could be identified by the increasing Si-O-Si bands around 1100 and 1250 cm(-1). mu XRF maps were recorded at different stages of the experiment at energies around the Mn-K edge (6.539 keV) and with a step size of 2 by 2 m. These confirm the leaching of K+ and Ca+2 from the glass and the intrusion of Mn from the solution. Mn was found throughout the entire gel layer, but with a concentration gradient peaking at the surface. XANES point measurements were recorded at various points where Mn was present. No spatial variation was found, but linear combination fitting of the spectra with various Mn reference compounds indicated that Mn2+Mn23+O4 is the main Mn compound in the gel layer, as was hypothesised by Watkinson et al. The standard corroded glass samples studied here can be used for the evaluation of conservation treatments in follow-up experiments. (C) 2013 The Authors. Published by Elsevier B.V. Selection and peer-review under responsibility of the IA-CS (Italian Association of Conservation Scientists) and University of Antwerp
Keywords: P1 Proceeding; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Times cited: 4
DOI: 10.1016/J.PROCHE.2013.03.030
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“Water quality assessment in Pangani river basin, Tanzania : natural and anthropogenic influences on concentrations of nutrients and inorganic ions”. Hellar-Kihampa H, De Wael K, Lugwisha E, Van Grieken R, International journal of river basin management 11, 55 (2013). http://doi.org/10.1080/15715124.2012.759119
Abstract: The ongoing rapid expansions of human activities and population dynamics have potential impact on the environmental quality of the Pangani river basin, one of the largest water resources in Tanzania, including possible loadings of different kinds of micro-contaminants. However, specific extents of the impacts are rather not well investigated. In this work, we assessed the environmental quality of the basin, based on seasonal characterisation of physicochemical water and sediments parameters, dissolved inorganic ions and nutrient loads. The contributions of geochemical processes and land-use practices were evaluated by multivariate correlations and principal component analysis (PCA). Hierarchical cluster analysis was used to classify similar water quality stations and identify the most and least enriched ones. Surface waters were slightly alkaline, characterised by low total dissolved solids (48652 mg/L). Extremely low oxygen concentration (2.0 mg/L) was also a cause of concern at one station. The Na+ and HCO3 − ions provided the dominant cation and anion, respectively. PCA identified weathering of carbonate and Na+ bearing rocks, gypsum dissolution and atmospheric deposition of sea-salt as the major factors controlling the ionic composition, contributing more than 60% of the spatial variance. Concentration profiles of the chemical species showed a generally low level of anthropogenic inputs, except at a few locations where nitrate and nitrite were significantly enriched above the limits of safe exposure, with patterns indicating influences of farming and livestock keeping. A seasonal difference was observed, with lower ion concentrations during the rainy season, likely due to the dilution effect of increased water discharge. The study provides new insights into the environmental quality of the basin, and indicates the need for continuous monitoring and assessment of the chemical species in the area.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1080/15715124.2012.759119
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“Diatom silica-titania materials for photocatalytic air purification”. Van Eynde E, Tytgat T, Smits M, Verbruggen S, Hauchecorne B, Blust R, Lenaerts S, Communications in agricultural and applied biological sciences 1, 141 (2013)
Keywords: A2 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
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“Integration of a photocatalytic coating in a corona discharge unit for plasma assisted catalysis”. Van Wesenbeeck K, Hauchecorne B, Lenaerts S, Journal of environmental solutions 2, 16 (2013)
Abstract: The combination of a non-thermal plasma with catalysis is considered as a sustainable indoor air purification technology to achieve complete oxidation at reduced energy cost with a longer electrode lifetime. An optimal window of operation for plasma assisted catalysis is found by varying the polarity, the applied voltage, the relative humidity of the gas phase and the configuration of the plasma reactor. The results show that, in general, negative corona discharge can obtain higher nitric oxide (NO) conversion efficiencies compared to positive corona. It is also clear that at higher applied voltages, higher conversion efficiency can be reached. The effect of relative humidity, however, is not found to be significant in the range (0 20.3 %) tested in this work. Additionally, the configuration of the plasma reactor is changed by varying the amount of pins that are attached at the collector electrode. The results show that there is an optimum at 10 pairs of pins to obtain a high conversion efficiency of NO. By applying a coating on the collector electrode of the plasma reactor, it is possible to see the influence of the coating on the performance of the plasma system, which was operating in the previously found optimal window. It stands clear that the use of a plasma assisted catalysis system has high potential as an integrated and sustainable indoor air purification technology.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
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“Plasma catalysis : integration of a photocatalytic coating in a corona discharge unit”. Van Wesenbeeck K, Hauchecorne B, Lenaerts S, (2013)
Keywords: P3 Proceeding; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
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“Study of a TiO2 photocatalytic coating for use in plasma catalysis”. Van Wesenbeeck K, Hauchecorne B, Lenaerts S, Communications in agricultural and applied biological sciences 78, 227 (2013)
Keywords: A2 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
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“The value of groundwater modeling to support a pump and treat design”. Compernolle T, Van Passel S, Lebbe L, Groundwater monitoring &, remediation 33, 111 (2013). http://doi.org/10.1111/GWMR.12018
Abstract: A wide range of rules, algorithms, and models are available to design an effective pump and treat remediation system. Often, one refers to the effectiveness of the developed pump and treat system to demonstrate how valuable the use of a groundwater model can be. An economic valuation of the groundwater model is usually missing. This study provides a framework that puts the discussion concerning the use of groundwater models in an economic perspective. It is not only demonstrated that a more effective pump and treat system can be designed using a groundwater model, but also the economic implications of using a groundwater model are calculated. A set of economic decision rules is applied to determine the economic value of a groundwater model. It is shown that investing in a groundwater model can be economically worthwhile. The remediation time is reduced, remediation costs are saved and the property can be sold more early. These benefits outweigh the costs of developing a groundwater model, and hence a positive net benefit (NB) is determined.
Keywords: A1 Journal article; Economics
DOI: 10.1111/GWMR.12018
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“Frustrated octahedral tilting distortion in the incommensurately modulated Li3xNd2/3-xTiO3 perovskites”. Abakumov AM, Erni R, Tsirlin AA, Rossell MD, Batuk D, Nénert G, Van Tendeloo G, Chemistry of materials 25, 2670 (2013). http://doi.org/10.1021/cm4012052
Abstract: Perovskite-structured titanates with layered A-site ordering form remarkably complex superstructures. Using transmission electron microscopy, synchrotron X-ray and neutron powder diffraction, and ab initio structure relaxation, we present the structural solution of the incommensurately modulated Li3xNd2/3xTiO3 perovskites (x = 0.05, superspace group Pmmm(α1,1/2,0)000(1/2,β2 0)000, a = 3.831048(5) Å, b = 3.827977(4) Å, c = 7.724356(8) Å, q1 = 0.45131(8)a* + 1/2b*, q2 = 1/2a* + 0.41923(4)b*). In contrast to earlier conjectures on the nanoscale compositional phase separation in these materials, all peculiarities of the superstructure can be understood in terms of displacive modulations related to an intricate octahedral tilting pattern. It involves fragmenting the pattern of the out-of-phase tilted TiO6 octahedra around the a- and b-axes into antiphase domains, superimposed on the pattern of domains with either pronounced or suppressed in-phase tilt component around the c-axis. The octahedral tilting competes with the second order JahnTeller distortion of the TiO6 octahedra. This competition is considered as the primary driving force for the modulated structure. The A cations are suspected to play a role in this modulation affecting it mainly through the tolerance factor and the size variance. The reported crystal structure calls for a revision of the structure models proposed for the family of layered A-site ordered perovskites exhibiting a similar type of modulated structure.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 23
DOI: 10.1021/cm4012052
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“Incommensurate modulation and luminescence in the CaGd2(1-x)Eu2x(MoO4)4(1-y)(WO)4y (0\leq x\leq1, 0\leq y\leq1) red phosphors”. Morozov VA, Bertha A, Meert KW, Van Rompaey S, Batuk D, Martinez GT, Van Aert S, Smet PF, Raskina MV, Poelman D, Abakumov AM, Hadermann J;, Chemistry of materials 25, 4387 (2013). http://doi.org/10.1021/cm402729r
Abstract: Scheelite related compounds (A',A '') [(B',B '')O-4], with B', B '' = W and/or Mo are promising new light-emitting materials for photonic applications, including phosphor converted LEDs (light-emitting diodes). In this paper, the creation and ordering of A-cation vacancies and the effect of cation substitutions in the scheelite-type framework are investigated as a factor for controlling the scheelite-type structure and luminescent properties. CaGd2(1-x)Eu2x(MoO4)(4(1-y))(WO4)(4y) (0 <= x <= 1, 0 <= y <= 1) solid solutions with scheelite-type structure were synthesized by a solid state method, and their structures were investigated using a combination of transmission electron microscopy techniques and powder X-ray diffraction. Within this series all complex molybdenum oxides have (3 + 2)D incommensurately modulated structures with superspace group I4(1)/a(alpha,beta,0)00(-beta,alpha,0)00, while the structures of all tungstates are (3 + 1)D incommensurately modulated with superspace group I2/b(alpha beta 0)00. In both cases the modulation arises because of cation-vacancy ordering at the A site. The prominent structural motif is formed by columns of A-site vacancies running along the c-axis. These vacant columns occur in rows of two or three aligned along the [110] direction of the scheelite subcell. The replacement of the smaller Gd3+ by the larger Eu3+ at the A-sublattice does not affect the nature of the incommensurate modulation, but an increasing replacement of Mo6+ by W6+ switches the modulation from (3 + 2)D to (3 + 1)D regime. Thus, these solid solutions can be considered as a model system where the incommensurate modulation can be monitored as a function of cation nature while the number of cation vacancies at the A sites remain constant upon the isovalent cation replacement. All compounds' luminescent properties were measured, and the optical properties were related to the structural properties of the materials. CaGd2(1-x)(MoO4)(4(1-y))(WO4)(4y) phosphors emit intense red light dominated by the D-5(0)-F-7(2) transition at 612 nm, along with other transitions from the D-5(1) and D-5(0) excited states. The intensity of the 5D0-7F2 transition reaches a maximum at x = 0.5 for y = 0 and 1.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 63
DOI: 10.1021/cm402729r
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“Synthesis and properties of charge-ordered thallium halide perovskites, CsTl0.5+Tl0.53+X3 (X = F or Cl) : theoretical precursors for superconductivity?”. Retuerto M, Emge T, Hadermann J, Stephens PW, Li MR, Yin ZP, Croft M, Ignatov A, Zhang SJ, Yuan Z, Jin C, Simonson JW, Aronson MC, Pan A, Basov DN, Kotliar G, Greenblatt M;, Chemistry of materials 25, 4071 (2013). http://doi.org/10.1021/cm402423x
Abstract: Recently, CsTlCl3 and CsTlF3 perovskites were theoretically predicted to be potential superconductors if they were optimally doped. The syntheses of these two compounds together with a complete characterization of the samples are reported. CsTlCl3 was obtained as orange crystals in two different polymorphs: a tetragonal phase (I4/m) and a cubic phase (Fm (3) over barm). CsTlF3 was formed as a light brown powder, and also as a double cubic perovskite (Fm (3) over barm). In all three CsTlX3 phases, Tl+ and Tl3+ were located in two different crystallographic positions that accommodate their different bond lengths. In CsTlCl3, some Tl vacancies were found in the Tl+ position. The charge ordering between Tl+ and Tl3+ was confirmed by X-ray absorption and Raman spectroscopy. The Raman spectroscopy of CsTlCl3 at high pressure (58 GPa) did not indicate any phase transition to a possible single Tl2+ state. However, the highly insulating material became less resistive with an increasing high pressure, while it underwent a change in its optical properties, from transparent to deeply opaque red, indicative of a decrease in the magnitude of the band gap. The theoretical design and experimental validation of the existence of CsTlF3 and CsTlCl3 cubic perovskites are the necessary first steps in confirming the theoretical prediction of superconductivity in these materials.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 28
DOI: 10.1021/cm402423x
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“Synthesis of highly luminescent silica-coated CdSe/CdS nanorods”. Pietra F, van Dijk-Moes RJA, Ke X, Bals S, Van Tendeloo G, de Mello Donega C, Vanmaekelbergh D, Chemistry of materials 25, 3427 (2013). http://doi.org/10.1021/cm401169t
Abstract: CdSe(core)/CdS(shell) nanorods (NRs) have been extensively investigated for their unique optical properties, such as high photoluminescence (PL) quantum efficiency (QE) and polarized light emission. The incorporation of these NRs in silica (SiO2) is of high interest, since this renders them processable in polar solvents while increasing their photochemical stability, which would be beneficial for their application in LEDs and as biolabels. We report the synthesis of highly luminescent silica-coated CdSe/CdS NRs, by using the reverse micelle method. The mechanism for the encapsulation of the NRs in silica is unravelled and shown to be strongly influenced by the NR shape and its asymmetry. This is attributed to both the different morphology and the different crystallographic nature of the facets terminating the opposite tips of the NRs. These results lead to the formation of a novel class of NR architectures, whose symmetry can be controlled by tuning the degree of coverage of the silica shell. Interestingly, the encapsulation of the NRs in silica leads to a remarkable increase in their photostability, while preserving their optical properties.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 46
DOI: 10.1021/cm401169t
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“Au@Ag nanoparticles : halides stabilize {100} facets”. Gómez-Graña S, Goris B, Altantzis T, Fernández-López C, Carbó-Argibay E, Guerrero-Martínez A, Almora-Barrios N, López N, Pastoriza-Santos I, Pérez-Juste J, Bals S, Van Tendeloo G, Liz-Marzán LM;, The journal of physical chemistry letters 4, 2209 (2013). http://doi.org/10.1021/jz401269w
Abstract: Seed-mediated growth is the most efficient methodology to control the size and shape of colloidal metal nanoparticles. In this process, the final nanocrystal shape is defined by the crystalline structure of the initial seed as well as by the presence of ligands and other additives that help to stabilize certain crystallographic facets. We analyze here the growth mechanism in aqueous solution of silver shells on presynthesized gold nanoparticles displaying various well-defined crystalline structures and morphologies. A thorough three-dimensional electron microscopy characterization of the morphology and internal structure of the resulting core-shell nanocrystals indicates that {100} facets are preferred for the outer silver shell, regardless of the morphology and crystallinity of the gold cores. These results are in agreement with theoretical analysis based on the relative surface energies of the exposed facets in the presence of halide ions.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 9.353
Times cited: 131
DOI: 10.1021/jz401269w
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“Dynamic motion of Ru-polyoxometalate ions (POMs) on functionalized few-layer graphene”. Ke X, Turner S, Quintana M, Hadad C, Montellano-López A, Carraro M, Sartorel A, Bonchio M, Prato M, Bittencourt C, Van Tendeloo G;, Small 9, 3922 (2013). http://doi.org/10.1002/smll.201300378
Abstract: The interaction and stability of Ru4POM on few layer graphene via functional groups is investigated by time-dependent imaging using aberration-corrected transmission electron microscopy. The Ru4POM demonstrates dynamic motion on the graphene surface with its frequency and amplitude of rotation related to the nature of the functional group used. The stability of the Ru4POMgraphene hybrid corroborates its long-term robustness when applied to multielectronic catalytic processes.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 8.643
Times cited: 16
DOI: 10.1002/smll.201300378
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“Casting light on the darkening of colors in historical paintings”. da Pieve F, Hogan C, Lamoen D, Verbeeck J, Vanmeert F, Radepont M, Cotte M, Janssens K, Gonze X, Van Tendeloo G, Physical review letters 111, 208302 (2013). http://doi.org/10.1103/PhysRevLett.111.208302
Abstract: The degradation of colors in historical paintings affects our cultural heritage in both museums and archeological sites. Despite intensive experimental studies, the origin of darkening of one of the most ancient pigments known to humankind, vermilion (α-HgS), remains unexplained. Here, by combining many-body theoretical spectroscopy and high-resolution microscopic x-ray diffraction, we clarify the composition of the damaged paint work and demonstrate possible physicochemical processes, induced by illumination and exposure to humidity and air, that cause photoactivation of the original pigment and the degradation of the secondary minerals. The results suggest a new path for the darkening process which was never considered by previous studies and prompt a critical examination of their findings.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 8.462
Times cited: 30
DOI: 10.1103/PhysRevLett.111.208302
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“Ciliary white light : optical aspect of ultrashort laser ablation on transparent dielectrics”. Liu Y, Brelet Y, He Z, Yu L, Mitryukovskiy S, Houard A, Forestier B, Couairon A, Mysyrowicz A, Physical review letters 110, 097601 (2013). http://doi.org/10.1103/PhysRevLett.110.097601
Abstract: We report on a novel nonlinear optical phenomenon, coined as ciliary white light, during laser ablation of transparent dielectrics. It is observed in 14 different transparent materials including glasses, crystals, and polymers. This phenomenon is also universal with respect to laser polarization, pulse duration, and focusing geometry. We interpret its formation in terms of the nonlinear diffraction of the laser generated white light by the ablation crater covered by nanostructures. It carries rich information on the damage profile and morphology dynamics of the ablated surface, providing a real time in situ observation of the laser ablation process. DOI: 10.1103/PhysRevLett.110.097601
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 8.462
Times cited: 10
DOI: 10.1103/PhysRevLett.110.097601
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“Comment on “Quantized orbital angular momentum transfer and magnetic dichroism in the interaction of electron vortices with matter””. Schattschneider P, Löffler S, Verbeeck J, Physical review letters 110, 189501 (2013). http://doi.org/10.1103/PhysRevLett.110.189501
Keywords: Editorial; Electron microscopy for materials research (EMAT)
Impact Factor: 8.462
Times cited: 8
DOI: 10.1103/PhysRevLett.110.189501
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