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Author Bals, S.; Batenburg, K.J.; Liang, D.; Lebedev, O.; Van Tendeloo, G.; Aerts, A.; Martens, J.A.; Kirschhock, C.E.
Title Quantitative three-dimensional modeling of zeotile through discrete electron tomography Type A1 Journal article
Year 2009 Publication Journal of the American Chemical Society Abbreviated Journal (up) J Am Chem Soc
Volume 131 Issue 13 Pages 4769-4773
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract Discrete electron tomography is a new approach for three-dimensional reconstruction of nanoscale objects. The technique exploits prior knowledge of the object to be reconstructed, which results in an improvement of the quality of the reconstructions. Through the combination of conventional transmission electron microscopy and discrete electron tomography with a model-based approach, quantitative structure determination becomes possible. In the present work, this approach is used to unravel the building scheme of Zeotile-4, a silica material with two levels of structural order. The layer sequence of slab-shaped building units could be identified. Successive layers were found to be related by a rotation of 120°, resulting in a hexagonal space group. The Zeotile-4 material is a demonstration of the concept of successive structuring of silica at two levels. At the first level, the colloid chemical properties of Silicalite-1 precursors are exploited to create building units with a slablike geometry. At the second level, the slablike units are tiled using a triblock copolymer to serve as a mesoscale structuring agent.
Address
Corporate Author Thesis
Publisher Place of Publication Washington, D.C. Editor
Language Wos 000264806300050 Publication Date 2009-03-16
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0002-7863;1520-5126; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 13.858 Times cited 58 Open Access
Notes Fwo; Iap; Esteem 026019 Approved Most recent IF: 13.858; 2009 IF: 8.580
Call Number UA @ lucian @ c:irua:76393 Serial 2767
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Author Hadermann, J.; Abakumov, A.M.; Adkin, J.J.; Hayward, M.A.
Title Topotactic reduction as a route to new close-packed anion deficient perovskites: structure and magnetism of 4H-BaMnO2+x Type A1 Journal article
Year 2009 Publication Journal of the American Chemical Society Abbreviated Journal (up) J Am Chem Soc
Volume 131 Issue 30 Pages 10598-10604
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The anion-deficient perovskite 4H-BaMnO2+x has been obtained by a topotactic reduction, with LiH, of the hexagonal perovskite 4H-BaMnO3−x. The crystal structure of 4H-BaMnO2+x was solved using electron diffraction and X-ray powder diffraction and further refined using neutron powder diffraction (S.G. Pnma, a = 10.375(2) Å, b = 9.466(2) Å, c = 11.276(3) Å, at 373 K). The orthorhombic superstructure arises from the ordering of oxygen vacancies within a 4H (chch) stacking of close packed c-type BaO2.5 and h-type BaO1.5 layers. The ordering of the oxygen vacancies transforms the Mn2O9 units of face-sharing MnO6 octahedra into Mn2O7 (two corner-sharing tetrahedra) and Mn2O6 (two edge-sharing tetrahedra) groups. The Mn2O7 and Mn2O6 groups are linked by corner-sharing into a three-dimensional framework. The structures of the BaO2.5 and BaO1.5 layers are different from those observed previously in anion-deficient perovskites providing a new type of order pattern of oxygen atoms and vacancies in close packed structures. Magnetization measurements and neutron diffraction data reveal 4H-BaMnO2+x adopts an antiferromagnetically ordered state below TN ≈ 350 K.
Address
Corporate Author Thesis
Publisher Place of Publication Washington, D.C. Editor
Language Wos 000268644400056 Publication Date 2009-07-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0002-7863;1520-5126; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 13.858 Times cited 25 Open Access
Notes Approved Most recent IF: 13.858; 2009 IF: 8.580
Call Number UA @ lucian @ c:irua:77928 Serial 3681
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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 (up) 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 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 (up) 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 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 (up) 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 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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Author Titantah, J.T.; Lamoen, D.; Schowalter, M.; Rosenauer, A.
Title Modified atomic scattering amplitudes and size effects on the 002 and 220 electron structure factors of multiple Ga1-xInxAs/GaAs quantum wells Type A1 Journal article
Year 2009 Publication Journal of applied physics Abbreviated Journal (up) J Appl Phys
Volume 105 Issue 8 Pages 084310,1-084310,8
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The modified atomic scattering amplitudes (MASAs) of mixed Ga<sub>1-x</sub>In<sub>x</sub>As, GaAs<sub>1-x</sub>N<sub>x</sub>, and InAs<sub>1-x</sub>N<sub>x</sub> are calculated using the density functional theory approach and the results are compared with those of the binary counterparts. The MASAs of N, Ga, As, and In for various scattering vectors in various chemical environments and in the zinc-blende structure are compared with the frequently used Doyle and Turner values. Deviation from the Doyle and Turner results is found for small scattering vectors (s<0.3 Å<sup>-1</sup>) and for these scattering vectors the MASAs are found to be sensitive to the orientation of the scattering vector and on the chemical environment. The chemical environment sensitive MASAs are used within zero pressure classical Metropolis Monte Carlo, finite temperature calculations to investigate the effect of well size on the electron 002 and 220 structure factors (SFs). The implications of the use of the 002 (200) spot for the quantification of nanostructured Ga<sub>1-x</sub>In<sub>x</sub>As systems are examined while the 220 SF across the well is evaluated and is found to be very sensitive to the in-plane static displacements.
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication New York, N.Y. Editor
Language Wos 000268064700149 Publication Date 2009-04-23
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-8979; ISBN Additional Links UA library record; WoS full record
Impact Factor 2.068 Times cited Open Access
Notes Fwo G.0425.05; Esteem 026019 Approved Most recent IF: 2.068; 2009 IF: 2.072
Call Number UA @ lucian @ c:irua:78282 Serial 2160
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Author Dhong, H.M.; Zhang, J.; Peeters, F.M.; Xu, W.
Title Optical conductance and transmission in bilayer graphene Type A1 Journal article
Year 2009 Publication Journal of applied physics Abbreviated Journal (up) J Appl Phys
Volume 106 Issue 4 Pages 043103,1-043103,6
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We present a theoretical study of the optoelectronic properties of bilayer graphene. The optical conductance and transmission coefficient are calculated using the energy-balance equation derived from a Boltzmann equation for an air/graphene/dielectric-wafer system. For short wavelengths (<0.2 µm), we obtain the universal optical conductance =e2/(2). Interestingly, there exists an optical absorption window in the wavelength range 10100 µm, which is induced by different transition energies required for inter- and intra-band optical absorptions in the presence of the MossBurstein effect. As a result, the position and width of this absorption window depend sensitively on temperature, carrier density, and sample mobility of the system. These results are relevant for applications of recently developed graphene devices in advanced optoelectronics such as the infrared photodetectors.
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication New York, N.Y. Editor
Language Wos 000270083800004 Publication Date 2009-08-20
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 2.068 Times cited 11 Open Access
Notes Approved Most recent IF: 2.068; 2009 IF: 2.072
Call Number UA @ lucian @ c:irua:79315 Serial 2472
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Author Zhang, Y.; Fischetti, M.V.; Sorée, B.; Magnus, W.; Heyns, M.; Meuris, M.
Title Physical modeling of strain-dependent hole mobility in Ge p-channel inversion layers Type A1 Journal article
Year 2009 Publication Journal of applied physics Abbreviated Journal (up) J Appl Phys
Volume 106 Issue 8 Pages 083704,1-083704,9
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We present comprehensive calculations of the low-field hole mobility in Ge p-channel inversion layers with SiO2 insulator using a six-band k·p band-structure model. The cases of relaxed, biaxially, and uniaxially (both tensily and compressively) strained Ge are studied employing an efficient self-consistent methodmaking use of a nonuniform spatial mesh and of the Broyden second methodto solve the coupled envelope-wave function k·p and Poisson equations. The hole mobility is computed using the KuboGreenwood formalism accounting for nonpolar hole-phonon scattering and scattering with interfacial roughness. Different approximations to handle dielectric screening are also investigated. As our main result, we find a large enhancement (up to a factor of 10 with respect to Si) of the mobility in the case of uniaxial compressive stress similarly to the well-known case of Si. Comparison with experimental data shows overall qualitative agreement but with significant deviations due mainly to the unknown morphology of the rough Ge-insulator interface, to additional scattering with surface optical phonon from the high- insulator, to Coulomb scattering interface traps or oxide chargesignored in our calculationsand to different channel structures employed.
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication New York, N.Y. Editor
Language Wos 000271358100050 Publication Date 2009-10-20
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 2.068 Times cited 29 Open Access
Notes Approved Most recent IF: 2.068; 2009 IF: 2.072
Call Number UA @ lucian @ c:irua:80137 Serial 2617
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Author Lin, K.; Pescarmona, P.P.; Houthoofd, K.; Liang, D.; Van Tendeloo, G.; Jacobs, P.A.
Title Direct room-temperature synthesis of methyl-functionalized Ti-MCM-41 nanoparticles and their catalytic performance in epoxidation Type A1 Journal article
Year 2009 Publication Journal of catalysis Abbreviated Journal (up) J Catal
Volume 263 Issue 1 Pages 75-82
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Methyl-functionalized Ti-MCM-41 nanoparticles with a size of 80 to 160 nm (Me-Ti-MCM-41 NP) were directly prepared via a dilute solution route by the co-condensation of tetraethoxysilane and methylalkoxysilanes in sodium hydroxide medium at room temperature. The characterization results showed the existence of ordered hexagonal mesoporous structure and tetrahedral Ti species in the nanoparticles. In the epoxidation of cyclohexene with tert-butyl hydroperoxide and aqueous H2O2, Me-Ti-MCM-41 NP samples displayed higher turnover frequencies (TOFs) for cyclohexene and initial reaction rates compared to Ti-MCM-41 and methyl-functionalized Ti-MCM-41 with normal particle size and to non-functionalized Ti-MCM-41 nanoparticles. Simultaneously, a higher selectivity for cyclohexene epoxide was observed in the case of aqueous H2O2, suggesting that the hydrolysis of cyclohexene epoxide with water is reduced on Me-Ti-MCM-41 NP samples. The improved catalytic behavior of Me-Ti-MCM-41 NP is discussed both in terms of the nanosize and methylation of the surface of the catalyst particles. The regeneration of Me-Ti-MCM-41 NP with tert-butyl hydroperoxide solution was evaluated via washing and calcination approaches.
Address
Corporate Author Thesis
Publisher Place of Publication San Diego, Calif. Editor
Language Wos 000265000800008 Publication Date 2009-02-14
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-9517; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.844 Times cited 89 Open Access
Notes Iwt; Iap; Goa Approved Most recent IF: 6.844; 2009 IF: 5.288
Call Number UA @ lucian @ c:irua:76395 Serial 720
Permanent link to this record
 
 
Author Verberck, B.; Vliegenthart, G.A.; Gompper, G.
Title Orientational ordering in solid C60 fullerene-cubane Type A1 Journal article
Year 2009 Publication The journal of chemical physics Abbreviated Journal (up) J Chem Phys
Volume 130 Issue 15 Pages 154510,1-154510,14
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We study the structure and phase behavior of fullerene-cubane C60·C8H8 by Monte Carlo simulation. Using a simple potential model capturing the icosahedral and cubic symmetries of its molecular constituents, we reproduce the experimentally observed phase transition from a cubic to an orthorhombic crystal lattice and the accompanying rotational freezing of the C60 molecules. We elaborate a scheme to identify the low-temperature orientations of individual molecules and to detect a pattern of orientational ordering similar to the arrangement of C60 molecules in solid C60. Our configuration of orientations supports a doubled periodicity along one of the crystal axes.
Address
Corporate Author Thesis
Publisher Place of Publication New York, N.Y. Editor
Language Wos 000265486300036 Publication Date 2009-04-22
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-9606; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.965 Times cited 8 Open Access
Notes Approved Most recent IF: 2.965; 2009 IF: 3.093
Call Number UA @ lucian @ c:irua:77258 Serial 2519
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Author Magnus, W.; Brosens, F.; Sorée, B.
Title Modeling drive currents and leakage currents : a dynamic approach Type A1 Journal article
Year 2009 Publication Journal of computational electronics Abbreviated Journal (up) J Comput Electron
Volume 8 Issue 3/4 Pages 307-323
Keywords A1 Journal article; Condensed Matter Theory (CMT); Theory of quantum systems and complex systems
Abstract The dynamics of electrons and holes propagating through the nano-scaled channels of modern semiconductor devices can be seen as a widespread manifestation of non-equilibrium statistical physics and its ruling principles. In this respect both the devices that are pushing conventional CMOS technology towards the final frontiers of Moores law and the upcoming set of alternative, novel nanostructures grounded on entirely new concepts and working principles, provide an almost unlimited playground for assessing physical models and numerical techniques emerging from classical and quantum mechanical non-equilibrium theory. In this paper we revisit the Boltzmann as well as the WignerBoltzmann equation which offers a valuable platform to study transport of charge carriers taking part in drive currents. We focus on a numerical procedure that regained attention recently as an alternative tool to solve the time-dependent Boltzmann equation for inhomogeneous systems, such as the channel regions of field-effect transistors, and we discuss its extension to the WignerBoltzmann equation. Furthermore, we pay attention to the calculation of tunneling leakage currents. The latter typically occurs in nano-scaled transistors when part of the carrier distribution sustaining the drive current is found to tunnel into the gate due the presence of an ultra-thin insulating barrier separating the gate from the channel region. In particular, we discuss the paradox related to the very existence of leakage currents established by electrons occupying quasi-bound states, while the (real) wave functions of the latter cannot carry net currents. Finally, we describe a simple model to resolve the paradox as well as to estimate gate currents provided the local carrier generation rates largely exceed the tunneling rates.
Address
Corporate Author Thesis
Publisher Place of Publication S.l. Editor
Language Wos 000208236100009 Publication Date 2009-09-28
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1569-8025;1572-8137; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.526 Times cited 4 Open Access
Notes Approved Most recent IF: 1.526; 2009 IF: NA
Call Number UA @ lucian @ c:irua:89503 Serial 2110
Permanent link to this record
 
 
Author Baguer, N.; Georgieva, V.; Calderin, L.; Todorov, I.T.; van Gils, S.; Bogaerts, A.
Title Study of the nucleation and growth of TiO2 and ZnO thin films by means of molecular dynamics simulations Type A1 Journal article
Year 2009 Publication Journal of crystal growth Abbreviated Journal (up) J Cryst Growth
Volume 311 Issue 16 Pages 4034-4043
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract The nucleation and growth of titanium dioxide (TiO2) and zinc oxide (ZnO) thin films on Fe2O3 (hematite), Al2O3 (á-alumina) and SiO2 (á-quartz) are studied by molecular dynamics simulations. The results show the formation of a strong interface region between the substrate and the film in the six systems studied here. A combination of polycrystalline and amorphous phases are observed in the TiO2 films grown on the three substrates. ZnO deposition on the Fe2O3 and Al2O3 crystals yields a monocrystalline film growth. The ZnO film deposited on the SiO2 crystal exhibits less crystallinity. The simulation results are compared with experimental results available in the literature.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000269580100012 Publication Date 2009-06-24
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-0248; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.751 Times cited 23 Open Access
Notes Approved Most recent IF: 1.751; 2009 IF: 1.534
Call Number UA @ lucian @ c:irua:77453 Serial 3338
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Author Van Passel, S.; Van Huylenbroeck, G.; Lauwers, L.; Mathijs, E.
Title Sustainable value assessment of farms using frontier efficiency benchmarks Type A1 Journal article
Year 2009 Publication Journal Of Environmental Management Abbreviated Journal (up) J Environ Manage
Volume 90 Issue 10 Pages 3057-3069
Keywords A1 Journal article; Economics
Abstract Appropriate assessment of firm sustainability facilitates actor-driven processes towards sustainable development. The methodology in this paper builds further on two proven methodologies for the assessment of sustainability performance: it combines the sustainable value approach with frontier efficiency benchmarks. The sustainable value methodology tries to relate firm performance to the use of different resources. This approach assesses contributions to corporate sustainability by comparing firm resource productivity with the resource productivity of a benchmark, and this for all resources considered. The efficiency is calculated by estimating the production frontier indicating the maximum feasible production possibilities. In this research, the sustainable value approach is combined with efficiency analysis methods to benchmark sustainability assessment. In this way, the production theoretical underpinnings of efficiency analysis enrich the sustainable value approach. The methodology is presented using two different functional forms: the CobbDouglas and the translog functional forms. The simplicity of the CobbDouglas functional form as benchmark is very attractive but it lacks flexibility. The translog functional form is more flexible but has the disadvantage that it requires a lot of data to avoid estimation problems. Using frontier methods for deriving firm specific benchmarks has the advantage that the particular situation of each company is taken into account when assessing sustainability. Finally, we showed that the methodology can be used as an integrative sustainability assessment tool for policy measures.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000269022800013 Publication Date 2009-06-24
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0301-4797 ISBN Additional Links UA library record; WoS full record; WoS citing articles; WoS full record; WoS citing articles
Impact Factor 4.01 Times cited 41 Open Access
Notes Approved Most recent IF: 4.01; 2009 IF: 2.367
Call Number UA @ admin @ c:irua:136762 Serial 6259
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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 (up) 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 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
Permanent link to this record
 
 
Author Nikolaev, A.V.; Michel, K.H.
Title Elusive s-f intrasite interactions and double exchange in solids: ferromagnetic versus nonmagnetic ground state Type A1 Journal article
Year 2009 Publication Journal of experimental and theoretical physics Abbreviated Journal (up) J Exp Theor Phys+
Volume 109 Issue 2 Pages 286-292
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract From the theory of many-electron states in atoms, we know that there exists a strong Coulomb repulsion, which results in the electronic term structure of atoms and is responsible for Hunds rules. By expanding the Coulomb on-site repulsion into a multipolar series, we derive this interaction and show that it is also present in solids as a correlation effect, which means that the interaction requires a multideterminant version of the Hartree-Fock method. Of particular interest is the case where this interaction couples states of localized ( f) and delocalized ( s) electrons. We show that the interaction is bilinear in the creation/annihilation operators for localized electrons and bilinear in the operators for conduction electrons. To study the coupling, we consider a simple model in the framework of an effective limited configuration interaction method with one localized f-electron and one itinerant s-electron per crystal site. The on-site multipole interaction between the f- and s-electrons is explicitly taken into account. It is shown that depending on the low-lying excitation spectrum imposed by the crystal electric field, the model can lead not only to ferromagnetism but also to a nonmagnetic state. The model is relevant for solids with localized and itinerant electron states.
Address
Corporate Author Thesis
Publisher Place of Publication Woodbury, N.Y. Editor
Language Wos 000270506500014 Publication Date 2009-09-18
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1063-7761;1090-6509; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.196 Times cited 3 Open Access
Notes Approved Most recent IF: 1.196; 2009 IF: 0.871
Call Number UA @ lucian @ c:irua:79163 Serial 1027
Permanent link to this record
 
 
Author Van Tendeloo, G.; Hadermann, J.; Abakumov, A.M.; Antipov, E.V.
Title Advanced electron microscopy and its possibilities to solve complex structures: application to transition metal oxides Type A1 Journal article
Year 2009 Publication Journal of materials chemistry Abbreviated Journal (up) J Mater Chem
Volume 19 Issue 18 Pages 2660-2670
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Design and optimization of materials properties can only be performed through a thorough knowledge of the structure of the compound. In this feature article we illustrate the possibilities of advanced electron microscopy in materials science and solid state chemistry. The different techniques are briefly discussed and several examples are given where the structures of complex oxides, often with a modulated structure, have been solved using electron microscopy.
Address
Corporate Author Thesis
Publisher Place of Publication Cambridge Editor
Language Wos 000265740600002 Publication Date 2009-02-04
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0959-9428;1364-5501; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor Times cited 9 Open Access
Notes Approved Most recent IF: NA
Call Number UA @ lucian @ c:irua:77065 Serial 68
Permanent link to this record
 
 
Author Hamelet, S.; Gibot, P.; Casas-Cabanas, M.; Bonnin, D.; Grey, C.P.; Cabana, J.; Leriche, J.B.; Rodriguez-Carvajal, J.; Courty, M.; Levasseur, S.; Carlach, P.; Van Thournout, M.; Tarascon, J.M.; Masquelier, C.;
Title The effects of moderate thermal treatments under air on LiFePO4-based nano powders Type A1 Journal article
Year 2009 Publication Journal of materials chemistry Abbreviated Journal (up) J Mater Chem
Volume 19 Issue 23 Pages 3979-3991
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The thermal behavior under air of LiFePO(4)-based powders was investigated through the combination of several techniques such as temperature-controlled X-ray diffraction, thermogravimetric analysis and Mossbauer and NMR spectroscopies. The reactivity with air at moderate temperatures depends on the particle size and leads to progressive displacement of Fe from the core structure yielding nano-size Fe(2)O(3) and highly defective, oxidized Li(x)Fe(y)PO(4) compositions whose unit-cell volume decreases dramatically when the temperature is raised between 400 and 600 K. The novel LiFePO(4)-like compositions display new electrochemical reactivity when used as positive electrodes in Li batteries. Several redox phenomena between 3.4 V and 2.7 V vs. Li were discovered and followed by in-situ X-ray diffraction, which revealed two distinct solid solution domains associated with highly anisotropic variations of the unit-cell constants.
Address
Corporate Author Thesis
Publisher Place of Publication Cambridge Editor
Language Wos 000266615800024 Publication Date 2009-05-05
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0959-9428;1364-5501; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor Times cited 93 Open Access
Notes Approved Most recent IF: NA
Call Number UA @ lucian @ c:irua:94582 Serial 867
Permanent link to this record
 
 
Author Esken, D.; Zhang, X.; Lebedev, O.I.; Schröder, F.; Fischer, R.A.
Title Pd@MOF-5: limitations of gas-phase infiltration and solution impregnation of [Zn4O(bdc)3] (MOF-5) with metalorganic palladium precursors for loading with Pd nanoparticles Type A1 Journal article
Year 2009 Publication Journal of materials chemistry Abbreviated Journal (up) J Mater Chem
Volume 19 Issue 9 Pages 1314-1319
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The limitations of the loading of the porous metalorganic framework [Zn4O(bdc)3] (bdc = benzene-1,4-dicarboxylate; MOF-5 or IRMOF-1) with Pd nanoparticles was investigated. First, the volatile organometallic precursor [Pd(5-C5H5)(3-C3H5)] was employed to get the inclusion compound [Pd(5-C5H5)(3-C3H5)]x@MOF-5 via gas-phase infiltration at 10-3 mbar. A loading of four molecules of [Pd(5-C5H5)(3-C3H5)] per formula unit of MOF-5 (x = 4) can be reached (35 wt.% Pd). Second, the metalorganic precursor [Pd(acac)2] (acac = 2,4-pentanedionate) was used and the inclusion materials [Pd(acac)2]x@MOF-5 of different Pd loadings were obtained by incipient wetness infiltration. However, the maximum loading was lower as compared with the former case with about two precursor molecules per formula unit of MOF-5. Both loading routes are suitable for the synthesis of Pd nanoparticles inside the porous host matrix. Homogeneously distributed nanoparticles with diameter of 2.4(±0.2) nm can be achieved by photolysis of the inclusion compounds [Pd(5-C5H5)(3-C3H5)]x@MOF-5 (x 4), while the hydrogenolysis of [Pd(acac)2]x@MOF-5 (x 2) leads to a mixture of small particles inside the network (< 3 nm) and large Pd agglomerates (40 nm) on the outer surface of the MOF-5 specimens. The pure Pdx@MOF-5 materials proved to be stable under hydrogen pressure (2 bar) at 150 °C over many hours. Neither hydrogenation of the bdc linkers nor particle growth was observed. The new composite materials were characterized by 1H/13C-MAS-NMR, powder XRD, ICP-AES, FT-IR, N2 sorption measurements and high resolution TEM. Raising the Pd loading of a representative sample Pd4@MOF-5 (35 wt.% Pd) by using [Pd(5-C5H5)(3-C3H5)] as precursor in a second cycle of gas-phase infiltration and photolysis was accompanied by the collapse of the long-range crystalline order of the MOF.
Address
Corporate Author Thesis
Publisher Place of Publication Cambridge Editor
Language Wos 000263450300015 Publication Date 2009-01-22
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0959-9428;1364-5501; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor Times cited 100 Open Access
Notes Approved Most recent IF: NA
Call Number UA @ lucian @ c:irua:76318 Serial 2565
Permanent link to this record
 
 
Author Smeulders, G.; Meynen, V.; van Baelen, G.; Mertens, M.; Lebedev, O.I.; Van Tendeloo, G.; Maes, B.U.W.; Cool, P.
Title Rapid microwave-assisted synthesis of benzene bridged periodic mesoporous organosilicas Type A1 Journal article
Year 2009 Publication Journal of materials chemistry Abbreviated Journal (up) J Mater Chem
Volume 19 Issue 19 Pages 3042-3048
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA); Organic synthesis (ORSY)
Abstract Following extended use in organic chemistry, microwave-assisted synthesis is gaining more importance in the field of inorganic chemistry, especially for the synthesis of nanoporous materials. It offers some major advantages such as a significant shortening of the synthesis time and an improved promotion of nucleation. In the research here reported, microwave technology is applied for the synthesis of benzene bridged PMOs (periodic mesoporous organosilicas). PMOs are one of the latest innovations in the field of hybrid ordered mesoporous materials and have attracted much attention because of their feasibility in electronics, catalysis, separation and sorption applications. The different synthesis steps (stirring, aging and extraction) of the classical PMO synthesis are replaced by microwave-assisted synthesis steps. The characteristics of the as-synthesized materials are evaluated by X-ray diffraction, N2-sorption, thermogravimetric analysis, scanning- and transmission electron microscopy. The microwave-assisted synthesis drastically reduces the synthesis time by more than 40 hours without any loss in structural properties, such as mesoscale and molecular ordering. The porosity of the PMO materials has even been improved by more than 25%. Moreover, the number of handling/transfer steps and amounts of chemicals and waste are drastically reduced. The study also shows that there is a clear time (1 to 3 hours) and temperature frame (373 K to 403 K) wherein synthesis of benzene bridged PMO is optimal. In conclusion, the microwave-assisted synthesis pathway allows an improved material to be obtained in a more economical way i.e. a much shorter time with fewer chemicals and less waste.
Address
Corporate Author Thesis
Publisher Place of Publication Cambridge Editor
Language Wos 000265919300024 Publication Date 2009-03-17
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0959-9428;1364-5501; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor Times cited 20 Open Access
Notes Fwo; Iwt Approved Most recent IF: NA
Call Number UA @ lucian @ c:irua:76844 Serial 2810
Permanent link to this record
 
 
Author Mandal, T.K.; Croft, M.; Hadermann, J.; Van Tendeloo, G.; Stephens, P.W.; Greenblatt, M.
Title La2MnVO6 double perovskite: a structural, magnetic and X-ray absorption investigation Type A1 Journal article
Year 2009 Publication Journal of materials chemistry Abbreviated Journal (up) J Mater Chem
Volume 19 Issue 25 Pages 4382-4390
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The synthesis, electron diffraction (ED), synchrotron X-ray and neutron structure, X-ray absorption spectroscopy (XAS) and magnetic property studies of La2MnVO6 double perovskite are described. Analysis of the synchrotron powder X-ray diffraction data for La2MnVO6 indicates a disordered arrangement of Mn and V at the B-site of the perovskite structure. Absence of super-lattice reflections in the ED patterns for La2MnVO6 supports the disordered cation arrangement. Room temperature time-of-flight (TOF) neutron powder diffraction (NPD) data show no evidence of cation ordering, in corroboration with the ED and synchrotron studies (orthorhombic Pnma, a = 5.6097(3), b = 7.8837(5) and c = 5.5668(3) ; 295 K, NPD). A comparison of XAS analyses of La2TVO6 with T = Ni and Co shows T2+ formal oxidation state while the T = Mn material evidences a Mn3+ admixture into a dominantly Mn2+ ground state. V-K edge measurements manifest a mirror image behavior with a V4+ state for T = Ni and Co with a V3+ admixture arising in the T = Mn material. The magnetic susceptibility data for La2MnVO6 show ferromagnetic correlations; the observed effective moment, µeff (5.72 µB) is much smaller than the calculated moment (6.16 µB) based on the spin-only formula for Mn2+ (d5, HS) /V4+ (d1), supportive of the partly oxidized Mn and reduced V scenario (Mn3+/V3+).
Address
Corporate Author Thesis
Publisher Place of Publication Cambridge Editor
Language Wos 000266989800015 Publication Date 2009-04-24
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0959-9428;1364-5501; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor Times cited 10 Open Access
Notes Approved Most recent IF: NA
Call Number UA @ lucian @ c:irua:77367 Serial 3540
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 (up) 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 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 Cao, S.; Tirry, W.; van den Broek, W.; Schryvers, D.
Title Optimization of a FIB/SEM slice-and-view study of the 3D distribution of Ni4Ti3 precipitates in NiTi Type A1 Journal article
Year 2009 Publication Journal of microscopy Abbreviated Journal (up) J Microsc-Oxford
Volume 233 Issue 1 Pages 61-68
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract The 3D morphology and distribution of lenticular Ni4Ti3 precipitates in the austenitic B2 matrix of a binary Ni51Ti49 alloy has been investigated by a slice-and-view procedure in a dual-beam focused ion beam/scanning electron microscope system. Due to the weak contrast of the precipitates, proper imaging conditions need to be selected first to allow for semi-automated image treatment. Knowledgeable imaging is further needed to ensure that all variants of the precipitates are observed with equal probability, regardless of sample orientation. Finally, a volume ratio of 10.2% for the Ni4Ti3 precipitates could be calculated, summed over all variants, which yields a net composition of Ni50.27Ti49.73 for the matrix, leading to an increase of 125 degrees for the martensitic start temperature. Also, the expected relative orientation of the different variants of the precipitates could be confirmed.
Address
Corporate Author Thesis
Publisher Place of Publication Oxford Editor
Language Wos 000262511900008 Publication Date 2009-01-15
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-2720;1365-2818; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.692 Times cited 22 Open Access
Notes Multimat Fwo; G0465.05 Approved Most recent IF: 1.692; 2009 IF: 1.612
Call Number UA @ lucian @ c:irua:76026 Serial 2486
Permanent link to this record
 
 
Author Neyts, E.C.; Bogaerts, A.
Title Numerical study of the size-dependent melting mechanisms of nickel nanoclusters Type A1 Journal article
Year 2009 Publication The journal of physical chemistry: C : nanomaterials and interfaces Abbreviated Journal (up) J Phys Chem C
Volume 113 Issue 7 Pages 2771-2776
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Molecular dynamics simulations were used to investigate the size-dependent melting mechanism of nickel nanoclusters of various sizes. The melting process was monitored by the caloric curve, the overall cluster Lindemann index, and the atomic Lindemann index. Size-dependent melting temperatures were determined, and the correct linear dependence on inverse diameter was recovered. We found that the melting mechanism gradually changes from dynamic coexistence melting to surface melting with increasing cluster size. These findings are of importance in better understanding carbon nanotube growth by catalytic chemical vapor deposition as the phase state of the catalyst nanoparticle codetermines the growth mechanism.
Address
Corporate Author Thesis
Publisher Place of Publication Washington, D.C. Editor
Language Wos Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1932-7447 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 4.536 Times cited Open Access
Notes Approved Most recent IF: 4.536; 2009 IF: 4.224
Call Number UA @ lucian @ c:irua:76495 Serial 2410
Permanent link to this record
 
 
Author Kolev, I.; Bogaerts, A.
Title Numerical study of the sputtering in a dc magnetron Type A1 Journal article
Year 2009 Publication Journal of vacuum science and technology: A: vacuum surfaces and films Abbreviated Journal (up) J Phys Chem C
Volume 27 Issue 1 Pages 20-28
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Molecular dynamics simulations were used to investigate the size-dependent melting mechanism of nickel nanoclusters of various sizes. The melting process was monitored by the caloric curve, the overall cluster Lindemann index, and the atomic Lindemann index. Size-dependent melting temperatures were determined, and the correct linear dependence on inverse diameter was recovered. We found that the melting mechanism gradually changes from dynamic coexistence melting to surface melting with increasing cluster size. These findings are of importance in better understanding carbon nanotube growth by catalytic chemical vapor deposition as the phase state of the catalyst nanoparticle codetermines the growth mechanism.
Address
Corporate Author Thesis
Publisher Place of Publication New York, N.Y. Editor
Language Wos 000263299600018 Publication Date 2009-02-03
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1932-7447;1932-7455; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 4.536 Times cited 66 Open Access
Notes Approved Most recent IF: 4.536; 2009 IF: 4.224
Call Number UA @ lucian @ c:irua:71634 Serial 2411
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 (up) 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 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 (up) 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 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 (up) 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 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 (up) 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 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 (up) 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 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
Permanent link to this record
 
 
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 (up) 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 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
Permanent link to this record