“Exciton states in a nanocup in the presence of a perpendicular magnetic field”. Arsoski V, Čukarić, N, Tadić, M, Peeters FM, Physica scripta T149, 014054 (2012). http://doi.org/10.1088/0031-8949/2012/T149/014054
Abstract: The exciton states in a strained (In,Ga)As/GaAs nanocup are theoretically determined. We explore how the nanocup bottom thickness (t) affects the magnetic field dependence of the exciton energy. Strain distribution is computed by the continuum mechanical model under the approximation of isotropic elasticity. The exciton wave functions are expanded into products of the electron and hole envelope functions. For small t, the exciton ground state has zero orbital momentum and exhibits small oscillations of the second derivative when the magnetic field increases. When t approaches the value of the cup height, however, the exciton levels exhibit angular momentum transitions, whose behavior is similar to that for type-II quantum dots. Small oscillations of the oscillator strength for exciton recombination are found when the magnetic field increases. An increase in thickness of the nanocup bottom has only a small effect on those oscillations for the optically active exciton states, but the exciton ground state becomes dark when the magnetic field increases. Hence, the results of our calculations show that an increase in thickness of the nanocup bottom transforms the exciton ground energy level dependence on magnetic field from the one characteristic of type-I rings to the one characteristic of type-II dots.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.28
Times cited: 2
DOI: 10.1088/0031-8949/2012/T149/014054
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“Experimental validation of edge strength model for glass with polished and cut edge finishing”. Vandebroek M, Belis J, Louter C, Van Tendeloo G, Engineering fracture mechanics 96, 480 (2012). http://doi.org/10.1016/j.engfracmech.2012.08.019
Abstract: In literature, the experimental validation of a glass edge strength model is lacking. Therefore, in this study, an edge strength model was established and validated. The short-term parameters of the edge strength model, i.e. the flaw geometry and depth, were determined by means of testing at a high stress rate. This was done for polished and cut edges. Next, the strength model, including subcritical crack growth, was established. Finally, the edge strength model was validated by the test results at a low stress rate. The assessed model was found to be slightly conservative, compared to the test results.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 2.151
Times cited: 15
DOI: 10.1016/j.engfracmech.2012.08.019
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Dixit H (2012) First-principles electronic structure calculations of transparent conducting oxide materials. Antwerpen
Keywords: Doctoral thesis; Condensed Matter Theory (CMT)
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Tan H (2012) From EELS to oxidation state mapping : an investigation into oxidation state mapping of transition metals with electron energy-loss spectroscopy. Antwerpen
Keywords: Doctoral thesis; Electron microscopy for materials research (EMAT)
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“From spin induced ferroelectricity to dipolar glasses : spinel chromites and mixed delafossites”. Maignan A, Martin C, Singh K, Simon C, Lebedev OI, Turner S, Journal of solid state chemistry 195, 41 (2012). http://doi.org/10.1016/j.jssc.2012.01.063
Abstract: Magnetoelectric multiferroics showing coupling between polarization and magnetic order are attracting much attention. For instance, they could be used in memory devices. Metal-transition oxides are provided several examples of inorganic magnetoelectric multiferroics. In the present short review, spinel and delafossite chromites are described. For the former, an electric polarization is evidenced in the ferrimagnetic state for ACr2O4 polycrystalline samples (A=Ni, Fe, Co). The presence of a JahnTeller cation such as Ni2+ at the A site is shown to yield larger polarization values. In the delafossites, substitution by V3+ at the Cr or Fe site in CuCrO2 (CuFeO2) suppresses the complex antiferromagnetic structure at the benefit of a spin glass state. The presence of cation disorder, probed by transmission electron microscopy, favors relaxor-like ferroelectricity. The results on the ferroelectricity of ferrimagnets and insulating spin glasses demonstrate that, in this research field, transition-metal oxides are worth to be studied.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.299
Times cited: 27
DOI: 10.1016/j.jssc.2012.01.063
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“Hardening in relation with microstructure evolution of high purity \alpha-titanium deformed under monotonic and cyclic simple shear loadings at room temperature”. Bouvier S, Benmhenni N, Tirry W, Gregory F, Nixon ME, Cazacu O, Rabet L, Materials science and engineering: part A: structural materials: properties, microstructure and processing 535, 12 (2012). http://doi.org/10.1016/j.msea.2011.12.033
Abstract: The aim of this paper is to gain understanding of the quasi-static, large strain deformation behavior at room-temperature of high-purity alpha-Ti with an initial split-basal texture. Simple shear tests were conducted along different directions in order to quantify the material's anisotropy and hardening evolution for different strain paths such as monotonic, Bauschinger, and cyclic loadings. The stress-strain curves indicate that the material displays strong anisotropy in the flow behavior. In order to capture the link between microstructure evolution (occurrence of twinning, grain size evolution, etc.) and the macroscopic response, a thoroughly detailed multi-scale characterization using scanning electron microscope (SEM) observations and electron backscattered diffraction (EBSD) analysis was also conducted. Specifically, EBSD analyses indicate that the twin activity and grain fragmentation are responsible for the observed difference between the macroscopic hardening rates corresponding to different directions and loading paths. (C) 2011 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.094
Times cited: 22
DOI: 10.1016/j.msea.2011.12.033
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“High magnetic ordering temperature in the perovskites Sr4-xLaxFe3ReO12 (x=0.0, 1.0, 2.0)”. Retuerto M, Li MR, Go YB, Ignatov A, Croft M, Ramanujachary KV, Herber RH, Nowik I, Hodges JP, Dachraoui W, Hadermann J, Greenblatt M;, Journal of solid state chemistry 194, 48 (2012). http://doi.org/10.1016/j.jssc.2012.06.031
Abstract: A series of perovskites Sr4−xLaxFe3ReO12 (x=0.0, 1.0, 2.0) has been prepared by wet chemistry methods. The structure analyses by powder X-ray and neutron diffraction and electron microscopy show that these compounds adopt simple perovskite structures without cation ordering over the B sites: tetragonal (I4/mcm) for x=0.0 and 1.0 and orthorhombic (Pbmn) for x=2.0. The oxidation states of the cations in the compound with x=0.0 appear to be Fe3+/4+ and Re7+ and decrease for both with La substitution as evidenced by X-ray absorption spectroscopy. All the compounds are antiferromagnetically ordered above room temperature, as demonstrated by Mössbauer spectroscopy and the magnetic structures, which were determined by powder neutron diffraction. The substitution of Sr by La strongly affects the magnetic properties with an increase of TN up to ∼750 K.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.299
Times cited: 9
DOI: 10.1016/j.jssc.2012.06.031
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“High-resolution visualization techniques : structural aspects”. Schryvers D, Van Aert S Springer, Berlin, page 135 (2012).
Keywords: H1 Book chapter; Electron microscopy for materials research (EMAT)
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“Imaging of intact MOF-5 nanocrystals by advanced TEM at liquid”. Wiktor C, Turner S, Zacher D, Fischer RA, Van Tendeloo G, Microporous and mesoporous materials: zeolites, clays, carbons and related materials 162, 131 (2012). http://doi.org/10.1016/j.micromeso.2012.06.014
Abstract: First results on the imaging of intact metalorganic framework (MOF) pores in MOF-5 nanocrystals by aberration corrected transmission electron microscopy (TEM) under liquid nitrogen conditions are presented. The applied technique is certainly transferable to other MOF systems, permitting detailed studies of MOF interfaces, MOFnanoparticle interaction and MOF thin films.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.615
Times cited: 30
DOI: 10.1016/j.micromeso.2012.06.014
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“Implementation of micro-ball nanodiamond anvils for high-pressure studies above 6 Mbar”. Dubrovinsky L, Dubrovinskaia N, Prakapenka VB, Abakumov AM, Nature communications 3, 1163 (2012). http://doi.org/10.1038/ncomms2160
Abstract: Since invention of the diamond anvil cell technique in the late 1950s for studying materials at extreme conditions, the maximum static pressure generated so far at room temperature was reported to be about 400 GPa. Here we show that use of micro-semi-balls made of nanodiamond as second-stage anvils in conventional diamond anvil cells drastically extends the achievable pressure range in static compression experiments to above 600 GPa. Micro-anvils (10-50 mu m in diameter) of superhard nano-diamond (with a grain size below similar to 50 nm) were synthesized in a large volume press using a newly developed technique. In our pilot experiments on rhenium and gold we have studied the equation of state of rhenium at pressures up to 640 GPa and demonstrated the feasibility and crucial necessity of the in situ ultra high-pressure measurements for accurate determination of material properties at extreme conditions.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
Times cited: 150
DOI: 10.1038/ncomms2160
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“Importance of twinning in static and dynamic compression of a Ti-6Al-4V titanium alloy with an equiaxed microstructure”. Coghe F, Tirry W, Rabet L, Schryvers D, Van Houtte P, Materials science and engineering: part A: structural materials: properties, microstructure and processing 537, 1 (2012). http://doi.org/10.1016/j.msea.2011.12.047
Abstract: Whereas deformation twinning is known to be an important deformation mechanism for hexagonal materials like magnesium and pure titanium, so far almost no literature exists on the twinning behaviour of the Ti-6Al-4V alloy. In this work it was shown that the activation of twinning as a deformation mechanism could have a pronounced effect on the mechanical behaviour of the Ti-6Al-4V alloy. This effect is even more pronounced under dynamic loading conditions. Transmission electron microscopy showed that only the {1 0 1 2}{1 0 1 1} tensile twin system was activated under certain loading conditions. Light-optical microscopy and electron backscatter diffraction data were afterwards used to experimentally determine the twin fractions. The importance of twinning for the texture evolution was also studied. It was shown that even small twin fractions can lead to distinct texture features, especially due to the discrete reorientation of the c-axes. The experimental results were compared to simulated results that were obtained with a viscoplastic self-consistent crystal plasticity code, after experimental validation that twinning can be reliably modelled as a unidirectional slip system. Although good agreement was obtained for the experimental and simulated stress-strain curves, the simulated results concerning twinning correlated well only on a qualitative basis as the simulated twin fractions were systematically higher than the experimental fractions. This seems to strengthen the hypothesis made by other research groups that complete grains might reorient by twinning. (C) 2011 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.094
Times cited: 35
DOI: 10.1016/j.msea.2011.12.047
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“Improved multislice calculations for including higher-order Laue zones effects”. Lobato I, van Dyck D, Ultramicroscopy 119, 63 (2012). http://doi.org/10.1016/j.ultramic.2012.01.003
Abstract: A new method for including higher-order Laue zones (HOLZs) effects in an efficient way in electron scattering simulations has been developed and tested by detail calculations. The calculated results by the conventional multislice (CMS) method and the improved conventional multislice (ICMS) method using a large dynamical aperture to avoid numerical errors are compared with accurate results. We have found that the zero-order Laue zones (ZOLZs) reflection cannot be properly described only using the projected potential in the whole unit cell; in general, we need to subslice the electrostatic potential inside the unit cell. It is shown that the ICMS method has higher accuracy than the CMS method for the calculation of the ZOLZ, HOLZ and Pseudo-HOLZ reflections. Hence, ICMS method allows to use a larger slice thickness than the CMS method and reduces the calculation time. (C) 2012 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 2.843
Times cited: 6
DOI: 10.1016/j.ultramic.2012.01.003
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“Influence of artificial pinning on vortex lattice instability in superconducting films”. Silhanek AV, Leo A, Grimaldi G, Berdiyorov GR, Milošević, MV, Nigro A, Pace S, Verellen N, Gillijns W, Metlushko V, Ilić, B, Zhu X, Moshchalkov VV;, New journal of physics 14, 053006 (2012). http://doi.org/10.1088/1367-2630/14/5/053006
Abstract: In superconducting films under an applied dc current, we analyze experimentally and theoretically the influence of engineered pinning on the vortex velocity at which the flux-flow dissipation undergoes an abrupt transition from low to high resistance. We argue, based on a nonuniform distribution of vortex velocity in the sample, that in strongly disordered systems the mean critical vortex velocity for flux-flow instability (i) has a nonmonotonic dependence on magnetic field and (ii) decreases as the pinning strength is increased. These findings challenge the generally accepted microscopic model of Larkin and Ovchinnikov (1979 J. Low. Temp. Phys. 34 409) and all subsequent refinements of this model which ignore the presence of pinning centers.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.786
Times cited: 40
DOI: 10.1088/1367-2630/14/5/053006
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“Interband optical absorption in a circular graphene quantum dot”. Grujić, M, Zarenia M, Tadić, M, Peeters FM, Physica scripta T149, 014056 (2012). http://doi.org/10.1088/0031-8949/2012/T149/014056
Abstract: We investigate the energy levels and optical properties of a circular graphene quantum dot in the presence of an external magnetic field perpendicular to the dot. Based on the Dirac-Weyl equation and assuming zero outward current at the edge of the dot we present the results for two different types of boundary conditions, i.e. infinite-mass (IMBC) and zigzag boundary conditions. We found that the dot with zigzag edges displays a zero-energy state in the energy spectra while this is not the case for the IMBCs. For both boundary conditions, the confinement becomes dominated by the magnetic field, where the energy levels converge to the Landau levels as the magnetic field increases. The effect of boundary conditions on the electron-and hole-energy states is found to affect the interband absorption spectra, where we found larger absorption in the case of IMBCs. The selection rules for interband optical transitions are determined and discussed for both boundary conditions.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.28
Times cited: 5
DOI: 10.1088/0031-8949/2012/T149/014056
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“Investigation of the elementary mechanisms controlling dislocation/twin boundary interactions in fcc metals and alloys : from conventional to advanced TEM characterization”. Idrissi H, Schryvers D Formatex Research Center, S.l., page 1213 (2012).
Keywords: H2 Book chapter; Electron microscopy for materials research (EMAT)
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“Modeling aspects of plasma-enhanced chemical vapor deposition of carbon-based materials”. Neyts E, Mao M, Eckert M, Bogaerts A CRC Press, Boca Raton, Fla, page 245 (2012).
Keywords: H1 Book chapter; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
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“Modeling of plasma and plasma-surface interactions for medical, environmental and nano applications”. Bogaerts A, Aerts R, Snoeckx R, Somers W, Van Gaens W, Yusupov M, Neyts E, Journal of physics : conference series 399, 012011 (2012). http://doi.org/10.1088/1742-6596/399/1/012011
Abstract: In this paper, an overview is given of modeling investigations carried out in our research group for a better understanding of plasmas used for medical, environmental and nano applications. The focus is both on modeling the plasma chemistry and the plasma-surface interactions. The plasma chemistry provides the densities and fluxes of the important plasma species. This information can be used as input when modeling the plasma-surface interactions. The combination of plasma simulations and plasma – surface interaction simulations provides a more comprehensive understanding of the underlying processes for these applications.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Times cited: 7
DOI: 10.1088/1742-6596/399/1/012011
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“Modeling the impact of junction angles in tunnel field-effect transistors”. Kao K-H, Verhulst AS, Vandenberghe WG, Sorée B, Groeseneken G, De Meyer K, Solid state electronics 69, 31 (2012). http://doi.org/10.1016/j.sse.2011.10.032
Abstract: We develop an analytical model for a tunnel field-effect transistor (TFET) with a tilted source junction angle. The tunnel current is derived by using circular tunnel paths along the electric field. The analytical model predicts that a smaller junction angle improves the TFET performance, which is supported by device simulations. An analysis is also made based on straight tunnel paths and tunnel paths corresponding to the trajectory of a classical particle. In all the aforementioned cases, the same conclusions are obtained. A TFET configuration with an encroaching polygon source junction is studied to analyze the junction angle dependence at the smallest junction angles. The improvement of the subthreshold swing (SS) with decreasing junction angle can be achieved by using thinner effective oxide thickness, smaller band gap material and longer encroaching length of the encroaching junction. A TFET with a smaller junction angle on the source side also has an innate immunity against the degradation of the fringing field from the gate electrode via a high-k spacer. A large junction angle on the drain side can suppress the unwanted ambipolar current of TFETs. (c) 2011 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.58
Times cited: 9
DOI: 10.1016/j.sse.2011.10.032
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“Optimization of operating parameters for inductively coupled plasma mass spectrometry : a computational study”. Aghaei M, Lindner H, Bogaerts A, Spectrochimica acta: part B : atomic spectroscopy 76, 56 (2012). http://doi.org/10.1016/j.sab.2012.06.006
Abstract: An inductively coupled plasma, connected to a mass spectrometer interface, is computationally investigated. The effect of pressure behind the sampler, injector gas flow rate, auxiliary gas flow rate, and applied power is studied. There seems to be an optimum range of injector gas flow rate for each setup which guaranties the presence and also a proper length of the central channel in the torch. Moreover, our modeling results show that for any specific purpose, it is possible to control that either only the central gas flow passes through the sampler orifice or that it is accompanied by the auxiliary gas flow. It was also found that depending on geometry, the variation of outgoing gas flow rate is much less than the variation of the injector gas flow rate and this causes a slightly higher pressure inside the torch. The general effect of increasing the applied power is a rise in the plasma temperature, which results in a higher ionization in the coil region. However, the negative effect is reducing the length of the cool central channel which is important to transfer the sample substances to the sampler. Using a proper applied power can enhance the efficiency of the system. Indeed, by changing the gas path lines, the power can control which flow (i.e., only from injector gas or also from the auxiliary gas) goes to the sampler orifice. Finally, as also reported from experiments in literature, the pressure behind the sampler has no dramatic effect on the plasma characteristics.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.241
Times cited: 18
DOI: 10.1016/j.sab.2012.06.006
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“Optimizing Er/Yb ratio and content in Er-Yb co-doped glass-ceramics for enhancement of the up- and down-conversion luminescence”. Tikhomirov VK, Rodríguez VD, Méndez-Ramos J, del- Castillo J, Kirilenko D, Van Tendeloo G, Moshchalkov VV, Solar energy materials and solar cells 100, 209 (2012). http://doi.org/10.1016/j.solmat.2012.01.019
Abstract: Er3+Yb3+ co-doped transparent glass-ceramics with varying Er/Yb content and ratio have been prepared. High quantum yields for up- and down-conversion luminescence by energy transfer from Yb3+ to Er3+ and from Er3+ to Yb3+, respectively, have been detected and optimized with respect to the Er/Yb content and ratio, and proposed in particular for up- and down-conversion of solar spectrum for enhancement of the efficiency of solar cells. The rise and decay kinetics for the population of the excited levels of Er3+ and Yb3+ have been studied and fit. Based on these experimental data, the mechanisms for the energy transfers have been suggested with emphasis on the optimized Er/Yb content and ratio for enhancement of the efficiency of the Er3+↔Yb3+ energy transfers.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.784
Times cited: 66
DOI: 10.1016/j.solmat.2012.01.019
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“Oxygen exchange on nanocrystalline tin dioxide modified by palladium”. Frolov DD, Kotovshchikov YN, Morozov IV, Boltalin AI, Fedorova AA, Marikutsa AV, Rumyantseva MN, Gaskov AM, Sadovskaya EM, Abakumov AM, Journal of solid state chemistry 186, 1 (2012). http://doi.org/10.1016/j.jssc.2011.11.028
Abstract: Temperature-programmed oxygen isotopic exchange study was performed on nanocrystalline tin dioxide-based materials synthesized via sol-gel route and modified by palladium. Such materials are widely used as resistive gas sensors. The experiments were carried out in a flow-reactor up to complete isotopic substitution of oxygen. Substantial rates of isotopic exchange for SnO2 were observed from about 700 K. The distribution of isotopic molecules O-16(2). (OO)-O-16-O-18 and O-18(2) corresponds to simple dioxygen heteroexchange mechanism with single lattice oxygen atom. The modification of SnO2 by Pd introduced multiple heteroexchange mechanism with preliminary O-2 dissociation on the clusters surface. Spill-over of atomic oxygen from Pd to the surface of SnO2 and fast exchange with lattice oxygen result in more than 100% increase of apparent heteroexchange rate. The exchange on SnO2/Pd was shown to be a complex process involving partial deactivation of the catalytic centers at temperature higher than 750 K. (C) 2011 Elsevier Inc. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.299
Times cited: 34
DOI: 10.1016/j.jssc.2011.11.028
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“Photocatalytic process optimisation for ethylene oxidation”. Tytgat T, Hauchecorne B, Abakumov AM, Smits M, Verbruggen SW, Lenaerts S, Chemical engineering journal 209, 494 (2012). http://doi.org/10.1016/j.cej.2012.08.032
Abstract: When studying photocatalysis it is important to consider, beside the chemical approach, the engineering part related to process optimisation. To achieve this a fixed bed photocatalytic set-up consisting of different catalyst placings, in order to vary catalyst distribution, is studied. The use of a fixed quantity of catalyst placed packed or randomly distributed in the reactor, results in an almost double degradation for the distributed catalyst. Applying this knowledge leads to an improved performance with limited use of catalyst. A reactor only half filled with catalyst leads to higher degradation performance compared to a completely filled reactor. Taking into account this simple process optimisation by better distributing the catalyst a more sustainable photocatalytic air purification process is achieved. (C) 2012 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 6.216
Times cited: 12
DOI: 10.1016/j.cej.2012.08.032
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“Precision of three-dimensional atomic scale measurements from HRTEM images : what are the limits?”.Wang A, Van Aert S, Goos P, van Dyck D, Ultramicroscopy 114, 20 (2012). http://doi.org/10.1016/j.ultramic.2011.12.002
Abstract: In this paper, we investigate to what extent high resolution transmission electron microscopy images can be used to measure the mass, in terms of thickness, and surface profile, corresponding to the defocus offset, of an object at the atomic scale. Therefore, we derive an expression for the statistical precision with which these object parameters can be estimated in a quantitative analysis. Evaluating this expression as a function of the microscope settings allows us to derive the optimal microscope design. Acquiring three-dimensional structure information in terms of thickness turns out to be much more difficult than obtaining two-dimensional information on the projected atom column positions. The attainable precision is found to be more strongly affected by processes influencing the image contrast, such as phonon scattering, than by the specific choice of microscope settings. For a realistic incident electron dose, it is expected that atom columns can be distinguished with single atom sensitivity up to a thickness of the order of the extinction distance. A comparable thickness limit is determined to measure surface steps of one atom. An increase of the electron dose shifts the limiting thickness upward due to an increase in the signal-to-noise ratio.
Keywords: A1 Journal article; Engineering Management (ENM); Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 2.843
Times cited: 5
DOI: 10.1016/j.ultramic.2011.12.002
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Heidari Mezerji H (2012) Quantitative electron tomography of nanoparticles. Antwerpen
Keywords: Doctoral thesis; Electron microscopy for materials research (EMAT)
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“Quantum simulations of electrostatics in Si cylindrical junctionless nanowire nFETs and pFETs with a homogeneous channel including strain and arbitrary crystallographic orientations”. Pham A-T, Sorée B, Magnus W, Jungemann C, Meinerzhagen B, Pourtois G, Solid state electronics 71, 30 (2012). http://doi.org/10.1016/j.sse.2011.10.016
Abstract: Simulation results of electrostatics in Si cylindrical junctionless nanowire transistors with a homogenous channel are presented. Junctionless transistors including strain and arbitrary crystallographic orientations are studied. Size quantization effects are simulated by self-consistent solutions of the Poisson and Schrodinger equations. The 6 x 6 k.p method is employed for the calculation of the valence subband structure in a junctionless nanowire pFET. The influence of stress/strain and crystallographic channel orientation on to the electrostatics in terms of subband structure, charge density, and C-V curve is systematically studied. (C) 2011 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 1.58
Times cited: 2
DOI: 10.1016/j.sse.2011.10.016
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“Recent results on characterization of detonation nanodiamonds”. Vlasov II, Turner S, Van Tendeloo G, Shiryaev AA Elsevier, Amsterdam, page 291 (2012).
Keywords: H3 Book chapter; Electron microscopy for materials research (EMAT)
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“Shallow donor near a semiconductor surface in the presence of locally spherical scanning tunneling microscope tip”. Djotyan AP, Avetisyan AA, Hao YL, Peeters FM, Proceedings of the Society of Photo-optical Instrumentation Engineers
T2 –, Conference on Photonics and Micro and Nano-structured Materials, JUN 28-30, 2011, Yerevan, ARMENIA , 84140 (2012). http://doi.org/10.1117/12.923562
Abstract: We developed a variational approach to investigate the ground state energy and the extend of the wavefunction of a neutral donor located near a semiconductor surface in the presence of scanning tunneling microscope (STM) metallic tip. We apply the effective mass approximation and use a variational wavefunction that takes into account the influence of all image charges that arise due to the presence of a metallic tip. The behavior of the ground state energy when the tip approaches the semiconductor surface is investigated.
Keywords: P1 Proceeding; Engineering sciences. Technology; Condensed Matter Theory (CMT)
DOI: 10.1117/12.923562
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“Statistical parameter estimation theory : a tool for quantitative electron microscopy”. Van Aert S Wiley-VCH, Weinheim, page 281 (2012).
Keywords: H1 Book chapter; Electron microscopy for materials research (EMAT)
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“Structure and high-temperature properties of the (Sr,Ca,Y)(Co,Mn)O3-y perovskites –, perspective cathode materials for IT-SOFC”. Napolsky PS, Drozhzhin OA, Istomin SY, Kazakov SM, Antipov EV, Galeeva AV, Gippius AA, Svensson G, Abakumov AM, Van Tendeloo G, Journal of solid state chemistry 192, 186 (2012). http://doi.org/10.1016/j.jssc.2012.03.056
Abstract: Oxygen deficient perovskites Sr0.75Y0.25Co1-xMnxO3-y, x=0.5 and 0.75, were prepared by using the citrate route at 1373-1573 K for 48 h. The cubic Pm-3m perovskite structure for x=0.5 was confirmed by electron diffraction study and refined using neutron powder diffraction (NPD) data. For x=0.75, the superstructure corresponding to a=root 2 x a(per), b=2 x a(per), c=root 2 x a(per) (a(0)b(-)b(-) tilt system, space group Imma) was revealed by electron diffraction. The solid solution Sr0.75-xCaxY0.25Co0.25Mn0.75O3-y, 0.1 <= x <= 0.6 and compound Ca0.75Y0.25Mn0.85Co0.15O2.92 were prepared in air at 1573 K for 48 h. The crystal structure of Ca0.75Y0.25Mn0.85Co0.15O2.92 was refined using NPD data (S.G. Pnma, a=5.36595(4), b=7.5091(6), c=5.2992(4) angstrom, R-p=0.057, R-wp=0.056, chi(2)=4.26). High-temperature thermal expansion properties of the prepared compounds were studied in air using both dilatometry and high-temperature X-ray powder diffraction data (HTXRPD). They expanding non-linearly at 298-1073 K due to the loss of oxygen at high temperatures. Calculated average thermal expansion coefficients (TECs) for Sr0.75Y0.25Co1-xMnxO3-y, x=0.5, 0.75 and Ca0.75Y0.25Mn0.85Co0.15O2.92(1) are 15.5, 15.1, and 13.8 ppm K-1, respectively. Anisotropy of the thermal expansion along different unit cell axes was observed for Sr0.15Ca0.6Y0.25Co0.25Mn0.75O3-y, and Ca0.75Y0.25Mn0.85Co0.15O2.92. Conductivity of Sr0.75Y0.25Co1-xMnxO3-y, x=0.5 and 0.75 increases with the temperature reaching 110 S/cm for x=0.5 and 44 S/cm for x=0.75 at 1173 K. Samples of Sr0.75-xCaxY0.25Co0.25Mn0.75O3-y, 0.1 <= y <= 0.6 were found to be n-type conductors at room temperature with the similar temperature dependence of the conductivity and demonstrated the increase of the sigma value from similar to 1 to similar to 50 S/cm as the temperature increases from 300 to 1173 K. Their conductivity is described in terms of the small polaron charge transport with the activation energy (E-p) increasing from 340 to 430 meV with an increase of the calcium content from x=0 to x=0.6. (C) 2012 Elsevier Inc. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.299
Times cited: 5
DOI: 10.1016/j.jssc.2012.03.056
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“Study of the interaction between copper and carbon nanotubes”. Bittencourt C, Ke X, Van Tendeloo G, Thiess S, Drube W, Ghijsen J, Ewels CP, Chemical physics letters 535, 80 (2012). http://doi.org/10.1016/j.cplett.2012.03.045
Abstract: Copper deposited by thermal evaporation onto pristine and oxygen plasma treated carbon nanotubes (CNTs) diffuse over the CNT surface, coalescing and forming crystalline islands. The nucleation sites of the islands are preferentially defects, and more homogeneous island dispersion was observed at the CNT oxygen functionalized surface. The presence of weakly bound oxygen atoms at the CNT surface induces the formation of CuO bonds at the Cu/CNT interface, as described through density functional calculations. Exposure to air allows further oxidation to facetted crystalline Cu2O. Oxygen plasma pre-treatment represents a promising route for homogenous disperse Cu2O nanoparticle decoration of CNTs.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.815
Times cited: 27
DOI: 10.1016/j.cplett.2012.03.045
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