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Author Van Aert, S.; Chang, L.Y.; Bals, S.; Kirkland, A.I.; Van Tendeloo, G.
Title Effect of amorphous layers on the interpretation of restored exit waves Type A1 Journal article
Year 2009 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 109 Issue 3 Pages 237-246
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The effects of amorphous layers on the quality of exit wave restorations have been investigated. Two independently developed software implementations for exit wave restoration have been used to simulated focal series of images of SrTiO3 with amorphous carbon layers incorporated. The restored exit waves have been compared both qualitatively and quantitatively. We have shown that amorphous layers have a strong impact on the quantitative measurements of atomic column positions, however, the error in the position measurements is still in the picometer range.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000264280200005 Publication Date 2008-11-15
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.843 Times cited 10 Open Access
Notes Fwo; Esteem 026019 Approved Most recent IF: 2.843; 2009 IF: 2.067
Call Number UA @ lucian @ c:irua:76421 Serial 796
Permanent link to this record
 
 
Author Verbeeck, J.; Sc hattschneider, P.; Rosenauer, A.
Title Image simulation of high resolution energy filtered TEM images Type A1 Journal article
Year 2009 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 109 Issue 4 Pages 350-360
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Inelastic image simulation software is presented, implementing the double channeling approximation which takes into account the combination of multiple elastic and single inelastic scattering in a crystal. The approach is described with a density matrix formalism. Two applications in high resolution energy filtered (EFTEM) transmission electron microscopy (TEM) images are presented: thickness-defocus maps for SrTiO3 and exit plane intensities for an (LaAlO3)3(SrTiO3)3 multilayer system. Both systems show a severe breakdown in direct interpretability which becomes worse for higher acceleration voltages, thicker samples and lower excitation edge energies. Since this effect already occurs in the exit plane intensity, it is a fundamental limit and image simulations in EFTEM are indispensable just as they are indispensable for elastic high resolution TEM images.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000265345400009 Publication Date 2009-01-17
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.843 Times cited 36 Open Access
Notes Fwo; Esteem 026019 Approved Most recent IF: 2.843; 2009 IF: 2.067
Call Number UA @ lucian @ c:irua:77272UA @ admin @ c:irua:77272 Serial 1552
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Author van den Broek, W.; Van Aert, S.; van Dyck, D.
Title A model based atomic resolution tomographic algorithm Type A1 Journal article
Year 2009 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 109 Issue 12 Pages 1485-1490
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract Tomography with high angular annular dark field scanning transmission electron microscopy at atomic resolution can be greatly improved if one is able to take advantage of prior knowledge. In this paper we present a reconstruction technique that explicitly takes into account the microscope parameters and the atomic nature of the projected object. This results in a more accurate estimate of the atomic positions and in a good resistance to noise. The reconstruction is a maximum likelihood estimator of the object. Moreover, the limits to the precision have been explored, allowing for a prediction of the amount of expected noise in the reconstruction for a certain experimental setup. We believe that the proposed reconstruction technique can be generalized to other tomographic experiments.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000271840200010 Publication Date 2009-08-28
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.843 Times cited 17 Open Access
Notes Approved Most recent IF: 2.843; 2009 IF: 2.067
Call Number UA @ lucian @ c:irua:78588 Serial 2097
Permanent link to this record
 
 
Author Van Aert, S.; Verbeeck, J.; Erni, R.; Bals, S.; Luysberg, M.; van Dyck, D.; Van Tendeloo, G.
Title Quantitative atomic resolution mapping using high-angle annular dark field scanning transmission electron microscopy Type A1 Journal article
Year 2009 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 109 Issue 10 Pages 1236-1244
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract A model-based method is proposed to relatively quantify the chemical composition of atomic columns using high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) images. The method is based on a quantification of the total intensity of the scattered electrons for the individual atomic columns using statistical parameter estimation theory. In order to apply this theory, a model is required describing the image contrast of the HAADF STEM images. Therefore, a simple, effective incoherent model has been assumed which takes the probe intensity profile into account. The scattered intensities can then be estimated by fitting this model to an experimental HAADF STEM image. These estimates are used as a performance measure to distinguish between different atomic column types and to identify the nature of unknown columns with good accuracy and precision using statistical hypothesis testing. The reliability of the method is supported by means of simulated HAADF STEM images as well as a combination of experimental images and electron energy-loss spectra. It is experimentally shown that statistically meaningful information on the composition of individual columns can be obtained even if the difference in averaged atomic number Z is only 3. Using this method, quantitative mapping at atomic resolution using HAADF STEM images only has become possible without the need of simultaneously recorded electron energy loss spectra.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000270015200004 Publication Date 2009-05-28
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.843 Times cited 166 Open Access
Notes Fwo; Esteem 026019 Approved Most recent IF: 2.843; 2009 IF: 2.067
Call Number UA @ lucian @ c:irua:78585UA @ admin @ c:irua:78585 Serial 2748
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Author Schattschneider, P.; Verbeeck, J.; Hamon, A.L.
Title Real space maps of atomic transitions Type A1 Journal article
Year 2009 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 109 Issue 7 Pages 781-787
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Considering the rapid technical development of transmission electron microscopes, we investigate the possibility to map electronic transitions in real space on the atomic scale. To this purpose, we analyse the information carried by the scatterer's initial and final state wave functions and the role of the different atomic transition channels for the inelastic scattering cross section. It is shown that the change in the magnetic quantum number in the transition can be mapped. Two experimental set-ups are proposed, one blocking half the diffraction plane, the other one using a cylinder lens for imaging. Both methods break the conventional circular symmetry in the electron microscope making it possible to detect the handedness of electronic transitions as an asymmetry in the image intensity. This finding is of important for atomic resolution energy-loss magnetic chiral dichroism (EMCD), allowing to obtain the magnetic moments of single atoms.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000266787900002 Publication Date 2009-03-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.843 Times cited 10 Open Access
Notes J.V. acknowledges the FWO-Vlaanderen for support (contract no. G.0147.06) and the European Union under the Framework 6 program under a contract for an Integrated Infrastructure Initiative. Reference 026019 ESTEEM. Approved Most recent IF: 2.843; 2009 IF: 2.067
Call Number UA @ lucian @ c:irua:77360UA @ admin @ c:irua:77360 Serial 2829
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Author Müller, K.; Schowalter, M.; Jansen, J.; Tsuda, K.; Titantah, J.; Lamoen, D.; Rosenauer, A.
Title Refinement of the 200 structure factor for GaAs using parallel and convergent beam electron nanodiffraction data Type A1 Journal article
Year 2009 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 109 Issue 7 Pages 802-814
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract We present a new method to measure structure factors from electron spot diffraction patterns recorded under almost parallel illumination in transmission electron microscopes. Bloch wave refinement routines have been developed to refine the crystal thickness, its orientation and structure factors by comparison of experimentally recorded and calculated intensities. Our method requires a modicum of computational effort, making it suitable for contemporary personal computers. Frozen lattice and Bloch wave simulations of GaAs diffraction patterns are used to derive optimised experimental conditions. Systematic errors are estimated from the application of the method to simulated diffraction patterns and rules for the recognition of physically reasonable initial refinement conditions are derived. The method is applied to the measurement of the 200 structure factor for GaAs. We found that the influence of inelastically scattered electrons is negligible. Additionally, we measured the 200 structure factor from zero loss filtered two-dimensional convergent beam electron diffraction patterns. The precision of both methods is found to be comparable and the results agree well with each other. A deviation of more than 20% from isolated atom scattering data is observed, whereas close agreement is found with structure factors obtained from density functional theory [A. Rosenauer, M. Schowalter, F. Glas, D. Lamoen, Phys. Rev. B 72 (2005), 085326-1], which account for the redistribution of electrons due to chemical bonding via modified atomic scattering amplitudes.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000266787900005 Publication Date 2009-03-23
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.843 Times cited 8 Open Access
Notes Fwo; G.0425.05; Esteem; Ant 200611271505 Approved Most recent IF: 2.843; 2009 IF: 2.067
Call Number UA @ lucian @ c:irua:77361 Serial 2856
Permanent link to this record
 
 
Author Ke, X.; Bals, S.; Romo Negreira, A.; Hantschel, T.; Bender, H.; Van Tendeloo, G.
Title TEM sample preparation by FIB for carbon nanotube interconnects Type A1 Journal article
Year 2009 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 109 Issue 11 Pages 1353-1359
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract A powerful method to study carbon nanotubes (CNTs) grown in patterned substrates for potential interconnects applications is transmission electron microscopy (TEM). However, high-quality TEM samples are necessary for such a study. Here, TEM specimen preparation by focused ion beam (FIB) has been used to obtain lamellae of patterned samples containing CNTs grown inside contact holes. A dual-cap Pt protection layer and an extensive 5 kV cleaning procedure are applied in order to preserve the CNTs and avoid deterioration during milling. TEM results show that the inner shell structure of the carbon nanotubes has been preserved, which proves that focused ion beam is a useful technique to prepare TEM samples of CNT interconnects.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000270765800006 Publication Date 2009-07-11
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.843 Times cited 21 Open Access
Notes Esteem 026019; Iap Approved Most recent IF: 2.843; 2009 IF: 2.067
Call Number UA @ lucian @ c:irua:79074 Serial 3485
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Author van den Broek, W.; Verbeeck, J.; Schryvers, D.; de Backer, S.; Scheunders, P.
Title Tomographic spectroscopic imaging; an experimental proof of concept Type A1 Journal article
Year 2009 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 109 Issue 4 Pages 296-303
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract Recording the electron energy loss spectroscopy data cube with a series of energy filtered images is a dose inefficient process because the energy slit blocks most of the electrons. When recording the data cube by scanning an electron probe over the sample, perfect dose efficiency is attained; but due to the low current in nanoprobes, this often is slower, with a smaller field of view. In W. Van den Broek et al. [Ultramicroscopy, 106 (2006) 269], we proposed a new method to record the data cube, which is more dose efficient than an energy filtered series. It produces a set of projections of the data cube and then tomographically reconstructs it. In this article, we demonstrate these projections in practice, we present a simple geometrical model that allows for quantification of the projection angles and we present the first successful experimental reconstruction, all on a standard post-column instrument.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000265345400003 Publication Date 2008-12-10
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.843 Times cited 1 Open Access
Notes Esteem 026019 Approved Most recent IF: 2.843; 2009 IF: 2.067
Call Number UA @ lucian @ c:irua:77271 Serial 3671
Permanent link to this record
 
 
Author Tomecka, D.M.; Kamieniarz, G.; Partoens, B.; Peeters, F.M.
Title Ground state configurations and melting of two-dimensional non-uniformly charged classical clusters Type A1 Journal article
Year 2009 Publication Journal of physics : condensed matter Abbreviated Journal J Phys-Condens Mat
Volume 21 Issue 15 Pages 155301,1-155301,7
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We consider classical two-dimensional (2D) Coulomb clusters consisting of two species containing five particles with charge q1 and five with charge q2, respectively. Using Monte Carlo and molecular dynamics (MD) simulations, we investigated the ground state configurations as well as radial and angular displacements of particles as a function of temperature and their dependence on the ratio q = q2/q1. We found new configurations and a new multi-step melting behavior for q sufficiently different from the uniform charge limit q = 1.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000264708600007 Publication Date 2009-03-18
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0953-8984;1361-648X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.649 Times cited 2 Open Access
Notes Approved Most recent IF: 2.649; 2009 IF: 1.964
Call Number UA @ lucian @ c:irua:76412 Serial 1384
Permanent link to this record
 
 
Author Chen, Y.; Croitoru, M.D.; Shanenko, A.A.; Peeters, F.M.
Title Superconducting nanowires: quantum confinement and spatially dependent Hartree-Fock potential Type A1 Journal article
Year 2009 Publication Journal of physics : condensed matter Abbreviated Journal J Phys-Condens Mat
Volume 21 Issue 43 Pages 435701,1-435701,7
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Abstract It is well known that, in bulk, the solution of the Bogoliubovde Gennes equations is the same whether or not the HartreeFock term is included. Here the HartreeFock potential is position independent and so gives the same contribution to both the single-electron energies and the Fermi level (the chemical potential). Thus, the single-electron energies measured from the Fermi level (they control the solution) stay the same. This is not the case for nanostructured superconductors, where quantum confinement breaks the translational symmetry and results in a position-dependent HartreeFock potential. In this case its contribution to the single-electron energies depends on the relevant quantum numbers. We numerically solved the Bogoliubovde Gennes equations with the HartreeFock term for a clean superconducting nanocylinder and found a shift of the curve representing the thickness-dependent oscillations of the critical superconducting temperature to larger diameters.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000270642700012 Publication Date 2009-10-09
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0953-8984;1361-648X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.649 Times cited 12 Open Access
Notes Approved Most recent IF: 2.649; 2009 IF: 1.964
Call Number UA @ lucian @ c:irua:79162 Serial 3360
Permanent link to this record
 
 
Author Zelaya, E.; Tolley, A.; Condo, A.M.; Schumacher, G.
Title Swift heavy ion irradiation of Cu-Zn-Al and Cu-Al-Ni alloys Type A1 Journal article
Year 2009 Publication Journal of physics : condensed matter Abbreviated Journal J Phys-Condens Mat
Volume 21 Issue 18 Pages 185009-185009,8
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The effects produced by swift heavy ions in the martensitic (18R) and austenitic phase (beta) of Cu based shape memory alloys were characterized. Single crystal samples with a surface normal close to [210](18R) and [001](beta) were irradiated with 200 MeV of Kr(15+), 230 MeV of Xe(15+), 350 and 600 MeV of Au(26+) and Au(29+). Changes in the microstructure were studied with transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). It was found that swift heavy ion irradiation induced nanometer sized defects in the 18R martensitic phase. In contrast, a hexagonal close-packed phase formed on the irradiated surface of beta phase samples. HRTEM images of the nanometer sized defects observed in the 18R martensitic phase were compared with computer simulated images in order to interpret the origin of the observed contrast. The best agreement was obtained when the defects were assumed to consist of local composition modulations.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000264934400014 Publication Date 2009-03-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0953-8984;1361-648X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.649 Times cited 8 Open Access
Notes Approved Most recent IF: 2.649; 2009 IF: 1.964
Call Number UA @ lucian @ c:irua:94551 Serial 3399
Permanent link to this record
 
 
Author Pereira, J.M.; Peeters, F.M.; Costa Filho, R.N.; Farias, G.A.
Title Valley polarization due to trigonal warping on tunneling electrons in graphene Type A1 Journal article
Year 2009 Publication Journal of physics : condensed matter Abbreviated Journal J Phys-Condens Mat
Volume 21 Issue 4 Pages 045301,1-045301,4
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The effect of trigonal warping on the transmission of electrons tunneling through potential barriers in graphene is investigated. We present calculations of the transmission coefficient for single and double barriers as a function of energy, incidence angle and barrier heights. The results show remarkable valley-dependent directional effects for barriers oriented parallel to the armchair or parallel to the zigzag direction. These results indicate that electrostatic gates can be used as valley filters in graphene-based devices.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000262354700004 Publication Date 2008-12-20
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0953-8984;1361-648X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.649 Times cited 78 Open Access
Notes Approved Most recent IF: 2.649; 2009 IF: 1.964
Call Number UA @ lucian @ c:irua:75736 Serial 3834
Permanent link to this record
 
 
Author Vast, L.; Carpentier, L.; Lallemand, F.; Colomer, J.-F.; Van Tendeloo, G.; Fonseca, A.; Nagy, J.B.; Mekhalif, Z.; Delhalle, J.
Title Multiwalled carbon nanotubes functionalized with 7-octenyltrichlorosilane and n-octyltrichlorosilane: dispersion in Sylgard®184 silicone and Youngs modulus Type A1 Journal article
Year 2009 Publication Journal of materials science Abbreviated Journal J Mater Sci
Volume 44 Issue 13 Pages 3476-3482
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Sylgard®184/multiwalled carbon nanotube (MWNT) composites have been prepared by in situ polymerization using purified and functionalized multiwalled carbon nanotubes (f-MWNTs) as fillers. Surface modification of the MWNTs has been carried out by silanization with 7-octenyltrichlorosilane (7OTCS) and n-octyltrichlorosilane (nOTCS). The modification and dispersion of the carbon nanotubes in composites were characterized by X-ray photoelectron spectroscopy (XPS), transmission electron spectroscopy (TEM), and high-resolution transmission electron spectroscopy (HRTEM). Youngs modulus results were derived from indentation testing. It is shown that the terminal-vinyl group of 7OTCS molecules plays an essential role for both the dispersion of the f-MWNTs in the composite and its mechanical properties. At loading as low as 0.2 wt%, the Youngs modulus is shown to increase up to 50%. This is interpreted as resulting from a combination of the good compatibility in the forming silicone matrix of the MWNTs coated with a siloxane network, on the one hand, and the covalent links created between the terminal-vinyl groups and the host matrix in formation, on the other hand.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000267153200022 Publication Date 2009-04-20
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-2461;1573-4803; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.599 Times cited 16 Open Access
Notes Iuap Approved Most recent IF: 2.599; 2009 IF: 1.471
Call Number UA @ lucian @ c:irua:77844 Serial 2245
Permanent link to this record
 
 
Author Bogaerts, A.; Bultinck, E.; Kolev, I.; Schwaederlé, L.; van Aeken, K.; Buyle, G.; Depla, D.
Title Computer modelling of magnetron discharges Type A1 Journal article
Year 2009 Publication Journal of physics: D: applied physics Abbreviated Journal J Phys D Appl Phys
Volume 42 Issue 19 Pages 194018,1-194018,12
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract In this paper, some modelling approaches to describe direct current (dc) magnetron discharges developed in our research groups will be presented, including an analytical model, Monte Carlo simulations for the electrons and for the sputtered atoms, a hybrid Monte Carlo-fluid model and particle-in-cell-Monte Carlo collision simulations. The strengths and limitations of the various modelling approaches will be explained, and some characteristic simulation results will be illustrated. Furthermore, some other simulation methods related to the magnetron device will be briefly explained, more specifically for calculating the magnetic field distribution inside the discharge, and for describing the (reactive) sputtering.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000269993100020 Publication Date 2009-09-19
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-3727;1361-6463; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.588 Times cited 32 Open Access
Notes Approved Most recent IF: 2.588; 2009 IF: 2.083
Call Number UA @ lucian @ c:irua:78168 Serial 462
Permanent link to this record
 
 
Author Petrović, D.; Martens, T.; van Dijk, J.; Brok, W.J.M.; Bogaerts, A.
Title Fluid modelling of an atmospheric pressure dielectric barrier discharge in cylindrical geometry Type A1 Journal article
Year 2009 Publication Journal of physics: D: applied physics Abbreviated Journal J Phys D Appl Phys
Volume 42 Issue 20 Pages 205206,1-205206,12
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract A numerical parameter study has been performed for a cylindrical atmospheric pressure dielectric barrier discharge (DBD) in helium with nitrogen impurities using a two-dimensional time-dependent fluid model. The calculated electric currents and gap voltages as a function of time for a given applied potential are presented, as well as the number densities of the various plasma species. This study shows that for the geometry under consideration the applied voltage parameters have a large impact on the electric current profiles and that the discharge current is always determined by the electron and ion conduction currents while the displacement current is nearly negligible. A relative broadening of the current profiles (compared with the duration of the half cycle of the applied voltage) with an increase in the applied frequency is obtained. Nearly sinusoidal current wave forms, usually typical for radio frequency DBDs, are observed while still operating at the frequencies of tens of kilohertz. For the setup under investigation, the Townsend mode of the DBD is observed in the entire range of applied voltage amplitudes and frequencies. It is shown that the average power density dissipated in the discharge increases with rising applied voltage and frequency. An increase in applied voltage frequency leads to an increase in the electron density and a decrease in electron energy, while increasing the voltage amplitude has the opposite effect.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000270563200028 Publication Date 2009-09-24
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-3727;1361-6463; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.588 Times cited 29 Open Access
Notes Approved Most recent IF: 2.588; 2009 IF: 2.083
Call Number UA @ lucian @ c:irua:78202 Serial 1228
Permanent link to this record
 
 
Author Tinck, S.; Boullart, W.; Bogaerts, A.
Title Investigation of etching and deposition processes of Cl2/O2/Ar inductively coupled plasmas on silicon by means of plasmasurface simulations and experiments Type A1 Journal article
Year 2009 Publication Journal of physics: D: applied physics Abbreviated Journal J Phys D Appl Phys
Volume 42 Issue Pages 095204,1-095204,13
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract In this paper, a simulation method is described to predict the etching behaviour of Cl2/O2/Ar inductively coupled plasmas on a Si substrate, as used in shallow trench isolation for the production of electronic devices. The hybrid plasma equipment model (HPEM) developed by Kushner et al is applied to calculate the plasma characteristics in the reactor chamber and two additional Monte Carlo simulations are performed to predict the fluxes, angles and energy of the plasma species bombarding the Si substrate, as well as the resulting surface processes such as etching and deposition. The simulations are performed for a wide variety of operating conditions such as gas composition, chamber pressure, power deposition and substrate bias. It is predicted by the simulations that when the fraction of oxygen in the gas mixture is too high, the oxidation of the Si substrate is superior to the etching of Si by chlorine species, resulting in an etch rate close to zero as is also observed in the experiments.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000265531000030 Publication Date 2009-04-16
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-3727;1361-6463; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.588 Times cited 23 Open Access
Notes Approved Most recent IF: 2.588; 2009 IF: 2.083
Call Number UA @ lucian @ c:irua:75601 Serial 1731
Permanent link to this record
 
 
Author Martens, T.; Brok, W.J.M.; van Dijk, J.; Bogaerts, A.
Title On the regime transitions during the formation of an atmospheric pressure dielectric barrier glow discharge Type A1 Journal article
Year 2009 Publication Journal of physics: D: applied physics Abbreviated Journal J Phys D Appl Phys
Volume 42 Issue 12 Pages 122002,1-122002,5
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract The atmospheric pressure dielectric barrier discharge in helium is a pulsed discharge in nature. If during the electrical current pulse a glow discharge is reached, then this pulse will last only a few microseconds in operating periods of sinusoidal voltage with lengths of about 10 to 100 µs. In this paper we demonstrate that right before a glow discharge is reached, the discharge very closely resembles the commonly assumed Townsend discharge structure, but actually contains some significant differing features and hence should not be considered as a Townsend discharge. In order to clarify this, we present calculation results of high time and space resolution of the pulse formation. The results indicate that indeed a maximum of ionization is formed at the anode, but that the level of ionization remains high and that the electric field at that time is significantly disturbed. Our results also show where this intermediate structure comes from.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000266639300002 Publication Date 2009-05-22
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-3727;1361-6463; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.588 Times cited 21 Open Access
Notes Approved Most recent IF: 2.588; 2009 IF: 2.083
Call Number UA @ lucian @ c:irua:76458 Serial 2450
Permanent link to this record
 
 
Author van Dijk, J.; Kroesen, G.M.W.; Bogaerts, A.
Title Plasma modelling and numerical simulation Type Editorial
Year 2009 Publication Journal of physics: D: applied physics Abbreviated Journal J Phys D Appl Phys
Volume 42 Issue 19 Pages 190301,1-190301,14
Keywords Editorial; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Plasma modelling is an exciting subject in which virtually all physical disciplines are represented. Plasma models combine the electromagnetic, statistical and fluid dynamical theories that have their roots in the 19th century with the modern insights concerning the structure of matter that were developed throughout the 20th century. The present cluster issue consists of 20 invited contributions, which are representative of the state of the art in plasma modelling and numerical simulation. These contributions provide an in-depth discussion of the major theories and modelling and simulation strategies, and their applications to contemporary plasma-based technologies. In this editorial review, we introduce and complement those papers by providing a bird's eye perspective on plasma modelling and discussing the historical context in which it has surfaced.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000269993100001 Publication Date 2009-09-19
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-3727;1361-6463; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.588 Times cited 64 Open Access
Notes Approved Most recent IF: 2.588; 2009 IF: 2.083
Call Number UA @ lucian @ c:irua:78166 Serial 2637
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Author Georgieva, V.; Saraiva, M.; Jehanathan, N.; Lebelev, O.I.; Depla, D.; Bogaerts, A.
Title Sputter-deposited Mg-Al-O thin films: linking molecular dynamics simulations to experiments Type A1 Journal article
Year 2009 Publication Journal of physics: D: applied physics Abbreviated Journal J Phys D Appl Phys
Volume 42 Issue 6 Pages 065107,1-065107,8
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Using a molecular dynamics model the crystallinity of MgxAlyOz thin films with a variation in the stoichiometry of the thin film is studied at operating conditions similar to the experimental operating conditions of a dual magnetron sputter deposition system. The films are deposited on a crystalline or amorphous substrate. The Mg metal content in the film ranged from 100% (i.e. MgO film) to 0% (i.e. Al2O3 film). The radial distribution function and density of the films are calculated. The results are compared with x-ray diffraction and transmission electron microscopy analyses of experimentally deposited thin films by the dual magnetron reactive sputtering process. Both simulation and experimental results show that the structure of the MgAlO film varies from crystalline to amorphous when the Mg concentration decreases. It seems that the crystalline MgAlO films have a MgO structure with Al atoms in between.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000263824200024 Publication Date 2009-03-03
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-3727;1361-6463; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.588 Times cited 37 Open Access
Notes Iwt Approved Most recent IF: 2.588; 2009 IF: 2.083
Call Number UA @ lucian @ c:irua:73246 Serial 3110
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Author Bergwerf, I.; de Vocht, N.; Tambuyzer, B.; Verschueren, J.; Reekmans, K.; Daans, J.; Ibrahimi, A.; Van Tendeloo, V.; Chatterjee, S.; Goossens, H.; Jorens, P.G.; Baekelandt, V.; Ysebaert, D.; Van Marck, E.; Berneman, Z.N.; Van Der Linden, A.; Ponsaerts, P.
Title Reporter gene-expressing bone marrow-derived stromal cells are immune-tolerated following implantation in the central nervous system of syngeneic immunocompetent mice Type A1 Journal article
Year 2009 Publication BMC biotechnology Abbreviated Journal Bmc Biotechnol
Volume Issue Pages
Keywords A1 Journal article; Antwerp Surgical Training, Anatomy and Research Centre (ASTARC); Laboratory Experimental Medicine and Pediatrics (LEMP); Bio-Imaging lab; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Background Cell transplantation is likely to become an important therapeutic tool for the treatment of various traumatic and ischemic injuries to the central nervous system (CNS). However, in many pre-clinical cell therapy studies, reporter gene-assisted imaging of cellular implants in the CNS and potential reporter gene and/or cell-based immunogenicity, still remain challenging research topics. Results In this study, we performed cell implantation experiments in the CNS of immunocompetent mice using autologous (syngeneic) luciferase-expressing bone marrow-derived stromal cells (BMSC-Luc) cultured from ROSA26-L-S-L-Luciferase transgenic mice, and BMSC-Luc genetically modified using a lentivirus encoding the enhanced green fluorescence protein (eGFP) and the puromycin resistance gene (Pac) (BMSC-Luc/eGFP/Pac). Both reporter gene-modified BMSC populations displayed high engraftment capacity in the CNS of immunocompetent mice, despite potential immunogenicity of introduced reporter proteins, as demonstrated by real-time bioluminescence imaging (BLI) and histological analysis at different time-points post-implantation. In contrast, both BMSC-Luc and BMSC-Luc/eGFP/Pac did not survive upon intramuscular cell implantation, as demonstrated by real-time BLI at different time-points post-implantation. In addition, ELISPOT analysis demonstrated the induction of IFN-ã-producing CD8+ T-cells upon intramuscular cell implantation, but not upon intracerebral cell implantation, indicating that BMSC-Luc and BMSC-Luc/eGFP/Pac are immune-tolerated in the CNS. However, in our experimental transplantation model, results also indicated that reporter gene-specific immune-reactive T-cell responses were not the main contributors to the immunological rejection of BMSC-Luc or BMSC-Luc/eGFP/Pac upon intramuscular cell implantation. Conclusion We here demonstrate that reporter gene-modified BMSC derived from ROSA26-L-S-L-Luciferase transgenic mice are immune-tolerated upon implantation in the CNS of syngeneic immunocompetent mice, providing a research model for studying survival and localisation of autologous BMSC implants in the CNS by real-time BLI and/or histological analysis in the absence of immunosuppressive therapy.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000262698500001 Publication Date 2009-01-07
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1472-6750 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.415 Times cited 33 Open Access
Notes Approved Most recent IF: 2.415; 2009 IF: 2.723
Call Number UA @ lucian @ c:irua:72911 Serial 4527
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Author Neyts, E.; Eckert, M.; Mao, M.; Bogaerts, A.
Title Numerical simulation of hydrocarbon plasmas for nanoparticle formation and the growth of nanostructured thin films Type A1 Journal article
Year 2009 Publication Plasma physics and controlled fusion Abbreviated Journal Plasma Phys Contr F
Volume 51 Issue Pages 124034,1-124034,8
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract This paper outlines two different numerical simulation approaches, carried out by our group, used for describing hydrocarbon plasmas in their applications for either nanoparticle formation in the plasma or the growth of nanostructured thin films, such as nanocrystalline diamond (NCD). A plasma model based on the fluid approach is utilized to study the initial mechanisms giving rise to nanoparticle formation in an acetylene plasma. The growth of NCD is investigated by molecular dynamics simulations, describing the interaction of the hydrocarbon species with a substrate.
Address
Corporate Author Thesis
Publisher Place of Publication Oxford Editor
Language Wos 000271940800045 Publication Date 2009-11-12
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0741-3335;1361-6587; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.392 Times cited 2 Open Access
Notes Approved Most recent IF: 2.392; 2009 IF: 2.409
Call Number UA @ lucian @ c:irua:79132 Serial 2405
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Author Tkachenko, D.V.; Misko, V.R.; Peeters, F.M.
Title Dynamics of colloids in a narrow channel driven by a nonuniform force Type A1 Journal article
Year 2009 Publication Physical review : E : statistical physics, plasmas, fluids, and related interdisciplinary topics Abbreviated Journal Phys Rev E
Volume 80 Issue 5 Pages 051401,1-051401,10
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Using Brownian dynamics simulations, we investigate the dynamics of colloids confined in two-dimensional narrow channels driven by a nonuniform force Fdr(y). We considered linear-gradient, parabolic, and deltalike driving-force profiles. This driving force induces melting of the colloidal solid (i.e., shear-induced melting), and the colloidal motion experiences a transition from elastic to plastic regime with increasing Fdr. For intermediate Fdr (i.e., in the transition region) the response of the system, i.e., the distribution of the velocities of the colloidal chains õi(y), in general does not coincide with the profile of the driving force Fdr(y), and depends on the magnitude of Fdr, the width of the channel, and the density of colloids. For example, we show that the onset of plasticity is first observed near the boundaries while the motion in the central region is elastic. This is explained by: (i) (in)commensurability between the chains due to the larger density of colloids near the boundaries, and (ii) the gradient in Fdr. Our study provides a deeper understanding of the dynamics of colloids in channels and could be accessed in experiments on colloids (or in dusty plasma) with, e.g., asymmetric channels or in the presence of a gradient potential field.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000272309500045 Publication Date 2009-11-10
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1539-3755;1550-2376; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.366 Times cited 14 Open Access
Notes Approved Most recent IF: 2.366; 2009 IF: 2.400
Call Number UA @ lucian @ c:irua:80313 Serial 774
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Author Yang, W.; Nelissen, K.; Kong, M.; Zeng, Z.; Peeters, F.M.
Title Structure of binary colloidal systems confined in a quasi-one-dimensional channel Type A1 Journal article
Year 2009 Publication Physical review : E : statistical physics, plasmas, fluids, and related interdisciplinary topics Abbreviated Journal Phys Rev E
Volume 79 Issue 4 Pages 041406,1-041406,6
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The structural properties of a binary colloidal quasi-one-dimensional system confined in a narrow channel are investigated through modified Monte Carlo simulations. Two species of particles with different magnetic moment interact through a repulsive dipole-dipole force are confined in a quasi-one-dimensional channel. The impact of three decisive parameters (the density of particles, the magnetic-moment ratio, and the fraction between the two species) on the transition from disordered phase to crystal-like phases and the transitions among the different mixed phases are summarized in a phase diagram.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000265941300077 Publication Date 2009-04-23
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1539-3755;1550-2376; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.366 Times cited 11 Open Access
Notes Approved Most recent IF: 2.366; 2009 IF: 2.400
Call Number UA @ lucian @ c:irua:77021 Serial 3308
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Author Lind, O.C.; Salbu, B.; Skipperud, L.; Janssens, K.; Jaroszewicz, J.; de Nolf, W.
Title Solid state speciation and potential bioavailability of depleted uranium particles from Kosovo and Kuwait Type A1 Journal article
Year 2009 Publication Journal of environmental radioactivity Abbreviated Journal J Environ Radioactiv
Volume 100 Issue 4 Pages 301-307
Keywords A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Abstract A combination of synchrotron radiation based X-ray microscopic techniques (ì-XRF, ì-XANES, ì-XRD) applied on single depleted uranium (DU) particles and semi-bulk leaching experiments has been employed to link the potential bioavailability of DU particles to site-specific particle characteristics. The oxidation states and crystallographic forms of U in DU particles have been determined for individual particles isolated from selected samples collected at different sites in Kosovo and Kuwait that were contaminated by DU ammunition during the 1999 Balkan conflict and the 1991 Gulf war. Furthermore, small soil or sand samples heavily contaminated with DU particles were subjected to simulated gastrointestinal fluid (0.16 M HCl) extractions. Characteristics of DU particles in Kosovo soils collected in 2000 and in Kuwait soils collected in 2002 varied significantly depending on the release scenario and to some extent on weathering conditions. Oxidized U (+6) was determined in large, fragile and bright yellow DU particles released during fire at a DU ammunition storage facility and crystalline phases such as schoepite (UO3·2.25H2O), dehydrated schoepite (UO3·0.75H2O) and metaschoepite (UO3·2.0H2O) were identified. As expected, these DU particles were rapidly dissolved in 0.16 M HCl (84 ± 3% extracted after 2 h) indicating a high degree of potential mobility and bioavailability. In contrast, the 2 h extraction of samples contaminated with DU particles originating either from corrosion of unspent DU penetrators or from impacted DU ammunition appeared to be much slower (2030%) as uranium was less oxidized (+4 to +6). Crystalline phases such as UO2, UC and metallic U or UTi alloy were determined in impacted DU particles from Kosovo and Kuwait, while the UO2,34 phase, only determined in particles from Kosovo, could reflect a more corrosive environment. Although the results are based on a limited number of DU particles, they indicate that the structure and extractability of DU particles released from similar sources (metallic U penetrators) will depend on the release scenarios (fire, impact) and to some extent environmental conditions. However, most of the DU particles (7396%) in all investigated samples were dissolved in 0.16 M HCl after one week indicating that a majority of the DU material is bioaccessible.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000264649500004 Publication Date 2009-02-18
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0265-931x ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.31 Times cited 49 Open Access
Notes Approved Most recent IF: 2.31; 2009 IF: 1.268
Call Number UA @ admin @ c:irua:76413 Serial 5834
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Author Abakumov, A.M.; Hadermann, J.; Tsirlin, A.A.; Tan, H.; Verbeeck, J.; Zhang, H.; Dikarev, E.V.; Shpanchenko, R.V.; Antipov, E.V.
Title Original close-packed structure and magnetic properties of the Pb4Mn9O20 manganite Type A1 Journal article
Year 2009 Publication Journal of solid state chemistry Abbreviated Journal J Solid State Chem
Volume 182 Issue 8 Pages 2231-2238
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The crystal structure of the Pb4Mn9O20 compound (previously known as Pb0.43MnO2.18) was solved from powder X-ray diffraction, electron diffraction, and high resolution electron microscopy data (S.G. Pnma, a=13.8888(2) Å, b=11.2665(2) Å, c=9.9867(1) Å, RI=0.016, RP=0.047). The structure is based on a 6H (cch)2 close packing of pure oxygen h-type (O16) layers alternating with mixed c-type (Pb4O12) layers. The Mn atoms occupy octahedral interstices formed by the oxygen atoms of the close-packed layers. The MnO6 octahedra share edges within the layers, whereas the octahedra in neighboring layers are linked through corner sharing. The relationship with the closely related Pb3Mn7O15 structure is discussed. Magnetization measurements reveal a peculiar magnetic behavior with a phase transition at 52 K, a small net magnetization below the transition temperature, and a tendency towards spin freezing.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000269066400035 Publication Date 2009-06-12
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4596; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.299 Times cited 5 Open Access
Notes The authors are grateful to Christoph Geibel for the help in magnetization measurements. A.Ts. acknowledges MPI CKS for hospitality and financial support during the stay. E.D. thanks the National Science Foundation (CHE-0718900) for financial support. This work was supported by the Russian Foundation of Basic Research (RFBR Grants 07-03-00664-a, 06-03-90168-a and 07-03-00890-a). The authors acknowledge financial support from the European Union under the Framework 6 program under a contract for an Integrated Infrastructure Initiative. Reference 026019 ESTEEM. Approved Most recent IF: 2.299; 2009 IF: 2.340
Call Number UA @ lucian @ c:irua:78935UA @ admin @ c:irua:78935 Serial 2529
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Author Bharathy, M.; Gemmill, W.R.; Fox, A.H.; Darriet, J.; Smith, M.D.; Hadermann, J.; Remy, M.S.; zur Loye, H.-C.
Title Synthesis and magnetic properties of rare earth ruthenates, Ln5Ru2O12 (Ln=Pr, Nd, SmTb) Type A1 Journal article
Year 2009 Publication Journal of solid state chemistry Abbreviated Journal J Solid State Chem
Volume 182 Issue 5 Pages 1164-1170
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Single crystals of Ln5Ru2O12 (Ln=Pr, Nd, SmTb) were grown out of either NaOH or KOH fluxes in sealed silver tubes. The crystals of all the phases were observed to be twinned as confirmed by TEM studies. The series crystallize in the C2/m monoclinic system with lattice parameters, a=12.4049(4)12.7621(6) Å, b=5.8414(2)5.9488(3) Å, c=7.3489(2)7.6424(4) Å, β=107.425(3)107.432(2)° and Z=2. The crystal structure is isotypic with the defect/disorder model of Ln5Re2O12 (Ln = Y, Gd) and consists of one dimensional edge shared RuO6 octahedral chains separated by a two dimensional LnOx polyhedral framework. Magnetic measurements indicate paramagnetic and antiferromagnetic behavior for Ln=Nd, SmGd and Ln=Tb, respectively.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000265893700027 Publication Date 2009-02-22
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4596; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.299 Times cited 4 Open Access
Notes Approved Most recent IF: 2.299; 2009 IF: 2.340
Call Number UA @ lucian @ c:irua:77052 Serial 3433
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Author d' Hondt, H.; Hadermann, J.; Abakumov, A.M.; Kalyuzhnaya, A.S.; Rozova, M.G.; Tsirlin, A.A.; Tan, H.; Verbeeck, J.; Antipov, E.V.; Van Tendeloo, G.
Title Synthesis, crystal structure and magnetic properties of the Sr2Al0.78Mn1.22O5.2 anion-deficient layered perovskite Type A1 Journal article
Year 2009 Publication Journal of solid state chemistry Abbreviated Journal J Solid State Chem
Volume 182 Issue 2 Pages 356-363
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract A new layered perovskite Sr2Al0.78Mn1.22O5.2 has been synthesized by solid state reaction in a sealed evacuated silica tube. The crystal structure has been determined using electron diffraction, high-resolution electron microscopy, and high-angle annular dark field imaging and refined from X-ray powder diffraction data (space group P4/mmm, a=3.89023(5) Å, c=7.8034(1) Å, RI=0.023, RP=0.015). The structure is characterized by an alternation of MnO2 and (Al0.78Mn0.22)O1.2 layers. Oxygen atoms and vacancies, as well as the Al and Mn atoms in the (Al0.78Mn0.22)O1.2 layers are disordered. The local atomic arrangement in these layers is suggested to consist of short fragments of brownmillerite-type tetrahedral chains of corner-sharing AlO4 tetrahedra interrupted by MnO6 octahedra, at which the chain fragments rotate over 90°. This results in an averaged tetragonal symmetry. This is confirmed by the valence state of Mn measured by EELS. The relationship between the Sr2Al0.78Mn1.22O5.2 tetragonal perovskite and the parent Sr2Al1.07Mn0.93O5 brownmillerite is discussed. Magnetic susceptibility measurements indicate spin glass behavior of Sr2Al0.78Mn1.22O5.2. The lack of long-range magnetic ordering contrasts with Mn-containing brownmillerites and is likely caused by the frustration of interlayer interactions due to presence of the Mn atoms in the (Al0.78Mn0.22)O1.2 layers.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000263124700022 Publication Date 2008-11-14
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4596; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.299 Times cited 12 Open Access
Notes Iap Vi Approved Most recent IF: 2.299; 2009 IF: 2.340
Call Number UA @ lucian @ c:irua:72943 Serial 3450
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Author Castelano, L.K.; Hai, G.Q.; Partoens, B.; Peeters, F.M.
Title Artificial molecular quantum rings under magnetic field influence Type A1 Journal article
Year 2009 Publication Journal of applied physics Abbreviated Journal J Appl Phys
Volume 106 Issue 7 Pages 073702,1-073702,8
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The ground states of a few electrons confined in two vertically coupled quantum rings in the presence of an external magnetic field are studied systematically within the current spin-density functional theory. Electron-electron interactions combined with inter-ring tunneling affect the electronic structure and the persistent current. For small values of the external magnetic field, we recover the zero magnetic field molecular quantum ring ground state configurations. Increasing the magnetic field many angular momentum, spin, and isospin transitions are predicted to occur in the ground state. We show that these transitions follow certain rules, which are governed by the parity of the number of electrons, the single-particle picture, Hunds rules, and many-body effects.
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication New York, N.Y. Editor
Language Wos 000270915600047 Publication Date 2009-10-03
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-8979; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.068 Times cited 5 Open Access
Notes Approved Most recent IF: 2.068; 2009 IF: 2.072
Call Number UA @ lucian @ c:irua:86926 Serial 155
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Author Pourghaderi, M.A.; Magnus, W.; Sorée, B.; Meuris, M.; de Meyer, K.; Heyns, M.
Title Ballistic current in metal-oxide-semiconductor field-effect transistors: the role of device topology Type A1 Journal article
Year 2009 Publication Journal of applied physics Abbreviated Journal J Appl Phys
Volume 106 Issue 5 Pages 053702,1-053702,8
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract In this study we investigate the effect of device topology on the ballistic current in n-channel metal-oxide-semiconductor field-effect transistors. Comparison of the nanoscale planar and double-gate devices reveals that, down to a certain thickness of the double gate film, the ballistic current flowing in the double gate device is twice as large compared to its planar counterpart. On the other hand, further thinning of the film beyond this threshold is found to change noticeably the confinement and transport characteristics, which are strongly depending on the film material and the surface orientation. For double gate Ge and Si devices there exists a critical film thickness below which the transverse gate field is no longer effectively screened by the inversion layer electron gas and mutual inversion of the two gates is turned on. In the case of GaAs and other similar IIIV compounds, a decrease in the film thickness may drastically change the occupation of the L-valleys and therefore amend the transport properties. The simulation results show that, in both cases, the ballistic current and the transconductance are considerably enhanced.
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication New York, N.Y. Editor
Language Wos 000269850300052 Publication Date 2009-09-03
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-8979; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.068 Times cited 3 Open Access
Notes Approved Most recent IF: 2.068; 2009 IF: 2.072
Call Number UA @ lucian @ c:irua:79744 Serial 214
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Author Ariskin, D.A.; Schweigert, I.V.; Alexandrov, A.L.; Bogaerts, A.; Peeters, F.M.
Title Modeling of chemical processes in the low pressure capacitive radio frequency discharges in a mixture of Ar/C2H2 Type A1 Journal article
Year 2009 Publication Journal of applied physics Abbreviated Journal J Appl Phys
Volume 105 Issue 6 Pages 063305,1-063305,9
Keywords A1 Journal article; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract We study the properties of a capacitive 13.56 MHz discharge with a mixture of Ar/C<sub>2</sub>H<sub>2</sub> taking into account the plasmochemistry and growth of heavy hydrocarbons. A hybrid model was developed to combine the kinetic description for electron motion and the fluid approach for negative and positive ion transports and plasmochemical processes. A significant change in plasma parameters related to injection of 5.8% portion of acetylene in argon was observed and analyzed. We found that the electronegativity of the mixture is about 30%. The densities of negatively and positively charged heavy hydrocarbons are sufficiently large to be precursors for the formation of nanoparticles in the discharge volume.
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication New York, N.Y. Editor
Language Wos 000264774000059 Publication Date 2009-03-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-8979; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) 2.068 Times cited 21 Open Access
Notes Approved Most recent IF: 2.068; 2009 IF: 2.072
Call Number UA @ lucian @ c:irua:74496 Serial 2121
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