| Records |
| Author |
Abakumov, A.M.; Batuk, D.; Hadermann, J.; Rozova, M.G.; Sheptyakov, D.V.; Tsirlin, A.A.; Niermann, D.; Waschowski, F.; Hemberger, J.; Van Tendeloo, G.; Antipov, E.V. |
| Title |
Antiferroelectric (Pb,Bi)1-xFe1+xO3-y perovskites modulated by crystallographic shear planes |
Type |
A1 Journal article |
| Year |
2011 |
Publication |
Chemistry of materials |
Abbreviated Journal |
Chem Mater |
Volume  |
23 |
Issue |
2 |
Pages |
255-265 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
We demonstrate for the first time a possibility to vary the anion content in perovskites over a wide range through a long-range-ordered arrangement of crystallographic shear (CS) planes. Anion-deficient perovskites (Pb,Bi)1−xFe1+xO3−y with incommensurately modulated structures were prepared as single phases in the compositional range from Pb0.857Bi0.094Fe1.049O2.572 to Pb0.409Bi0.567Fe1.025O2.796. Using a combination of electron diffraction and high-resolution scanning transmission electron microscopy, we constructed a superspace model describing a periodic arrangement of the CS planes. The model was verified by refinement of the Pb0.64Bi0.32Fe1.04O2.675 crystal structure from neutron powder diffraction data ((3 + 1)D S.G. X2/m(α0γ), X = [1/2,1/2,1/2,1/2], a = 3.9082(1) Å, b = 3.90333(8) Å, c = 4.0900(1) Å, β = 91.936(2)°, q = 0.05013(4)a* + 0.09170(3)c* at T = 700 K, RP = 0.036, RwP = 0.048). The (Pb,Bi)1−xFe1+xO3−y structures consist of perovskite blocks separated by CS planes confined to nearly the (509)p perovskite plane. Along the CS planes, the perovskite blocks are shifted with respect to each other over the 1/2[110]p vector that transforms the corner-sharing connectivity of the FeO6 octahedra in the perovskite framework to an edge-sharing connectivity of the FeO5 pyramids at the CS plane, thus reducing the oxygen content. Variation of the chemical composition in the (Pb,Bi)1−xFe1+xO3−y series occurs mainly because of a changing thickness of the perovskite block between the interfaces, that can be expressed through the components of the q vector as Pb6γ+2αBi1−7γ−αFe1+γ−αO3−3γ−α. The Pb, Bi, and Fe atoms are subjected to strong displacements occurring in antiparallel directions on both sides of the perovskite blocks, resulting in an antiferroelectric-type structure. This is corroborated by the temperature-, frequency-, and field-dependent complex permittivity measurements. Pb0.64Bi0.32Fe1.04O2.675 demonstrates a remarkably high resistivity >0.1 T Ω cm at room temperature and orders antiferromagnetically below TN = 608(10) K. |
| Address |
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| Corporate Author |
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Thesis |
|
| Publisher |
|
Place of Publication |
Washington, D.C. |
Editor |
|
| Language |
|
Wos |
000286160800018 |
Publication Date |
2010-12-23 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0897-4756;1520-5002; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
9.466 |
Times cited |
29 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 9.466; 2011 IF: 7.286 |
| Call Number |
UA @ lucian @ c:irua:88651 |
Serial |
136 |
| Permanent link to this record |
| |
|
| |
| Author |
Belik, A.A.; Abakumov, A.M.; Tsirlin, A.A.; Hadermann, J.; Kim, J.; Van Tendeloo, G.; Takayama-Muromachi, E. |
| Title |
Article Structure and magnetic properties of BiFe0.75Mn0.25O3 perovskite prepared at ambient and high pressure |
Type |
A1 Journal article |
| Year |
2011 |
Publication |
Chemistry of materials |
Abbreviated Journal |
Chem Mater |
| Volume |
23 |
Issue |
20 |
Pages |
4505-4514 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
Solid solutions of BiFe1xMnxO3 (0.0 ≤ x ≤ 0.4) were prepared at ambient pressure and at 6 GPa. The ambient-pressure (AP) phases crystallize in space group R3c similarly to BiFeO3. The high-pressure (HP) phases crystallize in space group R3c for x = 0.05 and in space group Pnma for 0.15 ≤ x ≤ 0.4. The structure of HP-BiFe0.75Mn0.25O3 was investigated using synchrotron X-ray powder diffraction, electron diffraction, and transmission electron microscopy. HP-BiFe0.75Mn0.25O3 has a PbZrO3-related √2ap × 4ap × 2√2ap (ap is the parameter of the cubic perovskite subcell) superstructure with a = 5.60125(9) Å, b = 15.6610(2) Å, and c = 11.2515(2) Å similar to that of Bi0.82La0.18FeO3. A remarkable feature of this structure is the unconventional octahedral tilt system, with the primary ab0a tilt superimposed on pairwise clockwise and counterclockwise rotations around the b-axis according to the oioi sequence (o stands for out-of-phase tilt, and i stands for in-phase tilt). The (FeMn)O6 octahedra are distorted, with one longer metaloxygen bond (2.222.23 Å) that can be attributed to a compensation for covalent BiO bonding. Such bonding results in the localization of the lone electron pair on Bi3+ cations, as confirmed by electron localization function analysis. The relationship between HP-BiFe0.75Mn0.25O3 and antiferroelectric structures of PbZrO3 and NaNbO3 is discussed. On heating in air, HP-BiFe0.75Mn0.25O3 irreversibly transforms to AP-BiFe0.75Mn0.25O3 starting from about 600 K. Both AP and HP phases undergo an antiferromagnetic ordering at TN ≈ 485 and 520 K, respectively, and develop a weak net magnetic moment at low temperatures. Additionally, ceramic samples of AP-BiFe0.75Mn0.25O3 show a peculiar phenomenon of magnetization reversal. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
|
Place of Publication |
Washington, D.C. |
Editor |
|
| Language |
|
Wos |
000295897400015 |
Publication Date |
2011-09-29 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0897-4756;1520-5002; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
9.466 |
Times cited |
57 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 9.466; 2011 IF: 7.286 |
| Call Number |
UA @ lucian @ c:irua:93581 |
Serial |
151 |
| Permanent link to this record |
| |
|
| |
| Author |
Neek-Amal, M.; Peeters, F.M. |
| Title |
Buckled circular monolayer graphene : a graphene nano-bowl |
Type |
A1 Journal article |
| Year |
2011 |
Publication |
Journal of physics : condensed matter |
Abbreviated Journal |
J Phys-Condens Mat |
| Volume |
23 |
Issue |
4 |
Pages |
045002-045002,8 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
We investigate the stability of circular monolayer graphene subjected to a radial load using non-equilibrium molecular dynamics simulations. When monolayer graphene is radially stressed, after some small circular strain (~0.4%) it buckles and bends into a new bowl-like shape. Young's modulus is calculated from the linear relation between stress and strain before the buckling threshold, which is in agreement with experimental results. The prediction of elasticity theory for the buckling threshold of a radially stressed plate is presented and its results are compared to the one of our atomistic simulation. The Jarzynski equality is used to estimate the difference between the free energy of the non-compressed states and the buckled states. From a calculation of the free energy we obtain the optimum radius for which the system feels the minimum boundary stress. |
| Address |
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| Corporate Author |
|
Thesis |
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| Publisher |
|
Place of Publication |
London |
Editor |
|
| Language |
|
Wos |
000286142800003 |
Publication Date |
2010-12-16 |
| 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 |
2.649 |
Times cited |
27 |
Open Access |
|
| Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vl) and the Belgian Science Policy (IAP). ; |
Approved |
Most recent IF: 2.649; 2011 IF: 2.546 |
| Call Number |
UA @ lucian @ c:irua:88043 |
Serial |
259 |
| Permanent link to this record |
| |
|
| |
| Author |
Yang, Z.; Schryvers, D. |
| Title |
Composition gradients surrounding Ni4Ti3 precipitates in a NiTi alloy studied by EELS, EFTEM and EDX |
Type |
A1 Journal article |
| Year |
2006 |
Publication |
International journal of applied electromagnetics and mechanics |
Abbreviated Journal |
Int J Appl Electrom |
| Volume |
23 |
Issue |
1/2 |
Pages |
17-24 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
|
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
Amsterdam |
Editor |
|
| Language |
|
Wos |
|
Publication Date |
0000-00-00 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1383-5416 |
ISBN |
|
Additional Links |
UA library record; WoS full record; |
| Impact Factor |
0.769 |
Times cited |
|
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 0.769; 2006 IF: 0.262 |
| Call Number |
UA @ lucian @ c:irua:59610 |
Serial |
443 |
| Permanent link to this record |
| |
|
| |
| Author |
Bogaerts, A. |
| Title |
Computer simulations of argon-hydrogen Grimm-type glow discharges |
Type |
A1 Journal article |
| Year |
2008 |
Publication |
Journal of analytical atomic spectrometry |
Abbreviated Journal |
J Anal Atom Spectrom |
| Volume |
23 |
Issue |
|
Pages |
1476-1486 |
| Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
| Abstract |
Computer simulations have been performed to describe the effect of small admixtures of hydrogen to an argon glow discharge in the Grimm-type configuration. The two-dimensional density profiles of the various plasma species (i.e., electrons, Ar+, ArH+, H+, H2+ and H3+ ions, H atoms and H2 molecules, Ar metastable atoms and sputtered Cu atoms) are presented for 1% H2 added to the argon glow discharge, and the effect of different H2 additions (varying between 0.1 and 10%) on the species densities, the hydrogen dissociation degree, and the sputtering process, are investigated. Finally, the relative contributions of various production and loss processes for the different plasma species are calculated. |
| Address |
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| Corporate Author |
|
Thesis |
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| Publisher |
|
Place of Publication |
London |
Editor |
|
| Language |
|
Wos |
000260309700002 |
Publication Date |
2008-10-23 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0267-9477;1364-5544; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.379 |
Times cited |
23 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 3.379; 2008 IF: 4.028 |
| Call Number |
UA @ lucian @ c:irua:70950 |
Serial |
468 |
| Permanent link to this record |
| |
|
| |
| Author |
Ray, S.; Kolen'ko, Y.V.; Kovnir, K.A.; Lebedev, O.I.; Turner, S.; Chakraborty, T.; Erni, R.; Watanabe, T.; Van Tendeloo, G.; Yoshimura, M.; Itoh, M. |
| Title |
Defect controlled room temperature ferromagnetism in Co-doped barium titanate nanocrystals |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Nanotechnology |
Abbreviated Journal |
Nanotechnology |
| Volume |
23 |
Issue |
2 |
Pages |
025702,1-025702,10 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
Defect mediated high temperature ferromagnetism in oxide nanocrystallites is the central feature of this work. Here, we report the development of room temperature ferromagnetism in nanosized Co-doped barium titanate particles with a size of around 14 nm, synthesized by a solvothermal drying method. A combination of x-ray diffraction with state-of-the-art electron microscopy techniques confirms the intrinsic doping of Co into BaTiO3. The development of the room temperature ferromagnetism was tracked down to the different donor defects, namely hydroxyl groups at the oxygen site (\mathrm {OH}\mathrm {(O)} |
| Address |
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| Corporate Author |
|
Thesis |
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| Publisher |
|
Place of Publication |
Bristol |
Editor |
|
| Language |
|
Wos |
000298409000011 |
Publication Date |
2011-12-14 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0957-4484;1361-6528; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.44 |
Times cited |
19 |
Open Access |
|
| Notes |
Esteem 026019; Fwo |
Approved |
Most recent IF: 3.44; 2012 IF: 3.842 |
| Call Number |
UA @ lucian @ c:irua:93636 |
Serial |
614 |
| Permanent link to this record |
| |
|
| |
| Author |
Huijben, M.; Koster, G.; Kruize, M.K.; Wenderich, S.; Verbeeck, J.; Bals, S.; Slooten, E.; Shi, B.; Molegraaf, H.J.A.; Kleibeuker, J.E.; Van Aert, S.; Goedkoop, J.B.; Brinkman, A.; Blank, D.H.A.; Golden, M.S.; Van Tendeloo, G.; Hilgenkamp, H.; Rijnders, G.; |
| Title |
Defect engineering in oxide heterostructures by enhanced oxygen surface exchange |
Type |
A1 Journal article |
| Year |
2013 |
Publication |
Advanced functional materials |
Abbreviated Journal |
Adv Funct Mater |
| Volume |
23 |
Issue |
42 |
Pages |
5240-5248 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
| Abstract |
The synthesis of materials with well-controlled composition and structure improves our understanding of their intrinsic electrical transport properties. Recent developments in atomically controlled growth have been shown to be crucial in enabling the study of new physical phenomena in epitaxial oxide heterostructures. Nevertheless, these phenomena can be influenced by the presence of defects that act as extrinsic sources of both doping and impurity scattering. Control over the nature and density of such defects is therefore necessary to fully understand the intrinsic materials properties and exploit them in future device technologies. Here, it is shown that incorporation of a strontium copper oxide nano-layer strongly reduces the impurity scattering at conducting interfaces in oxide LaAlO3SrTiO3(001) heterostructures, opening the door to high carrier mobility materials. It is proposed that this remote cuprate layer facilitates enhanced suppression of oxygen defects by reducing the kinetic barrier for oxygen exchange in the hetero-interfacial film system. This design concept of controlled defect engineering can be of significant importance in applications in which enhanced oxygen surface exchange plays a crucial role. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
Weinheim |
Editor |
|
| Language |
|
Wos |
000327480900003 |
Publication Date |
2013-06-10 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1616-301X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
12.124 |
Times cited |
87 |
Open Access |
|
| Notes |
Countatoms; Vortex; Fwo; Ifox ECASJO_; |
Approved |
Most recent IF: 12.124; 2013 IF: 10.439 |
| Call Number |
UA @ lucian @ c:irua:109273UA @ admin @ c:irua:109273 |
Serial |
615 |
| Permanent link to this record |
| |
|
| |
| Author |
Shi, J.M.; Koenraad, P.M.; van de Stadt, A.F.W.; Peeters, F.M.; Devreese, J.T.; Wolter, J.H. |
| Title |
DX-center and pressure effects on electronic structure of a δ-doped quantum barrier |
Type |
A1 Journal article |
| Year |
1998 |
Publication |
Superlattices and microstructures |
Abbreviated Journal |
Superlattice Microst |
| Volume |
23 |
Issue |
|
Pages |
83-86 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT); Theory of quantum systems and complex systems |
| Abstract |
|
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
London |
Editor |
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| Language |
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Wos |
000072338200015 |
Publication Date |
2002-10-07 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0749-6036; |
ISBN |
|
Additional Links |
UA library record; WoS full record |
| Impact Factor |
2.123 |
Times cited |
|
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 2.123; 1998 IF: 0.831 |
| Call Number |
UA @ lucian @ c:irua:28908 |
Serial |
759 |
| Permanent link to this record |
| |
|
| |
| Author |
Schulze, A.; Hantschel, T.; Dathe, A.; Eyben, P.; Ke, X.; Vandervorst, W. |
| Title |
Electrical tomography using atomic force microscopy and its application towards carbon nanotube-based interconnects |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Nanotechnology |
Abbreviated Journal |
Nanotechnology |
| Volume |
23 |
Issue |
30 |
Pages |
305707 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
| Abstract |
The fabrication and integration of low-resistance carbon nanotubes (CNTs) for interconnects in future integrated circuits requires characterization techniques providing structural and electrical information at the nanometer scale. In this paper we present a slice-and-view approach based on electrical atomic force microscopy. Material removal achieved by successive scanning using doped ultra-sharp full-diamond probes, manufactured in-house, enables us to acquire two-dimensional (2D) resistance maps originating from different depths (equivalently different CNT lengths) on CNT-based interconnects. Stacking and interpolating these 2D resistance maps results in a three-dimensional (3D) representation (tomogram). This allows insight from a structural (e.g. size, density, distribution, straightness) and electrical point of view simultaneously. By extracting the resistance evolution over the length of an individual CNT we derive quantitative information about the resistivity and the contact resistance between the CNT and bottom electrode. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
Bristol |
Editor |
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| Language |
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Wos |
000306333500029 |
Publication Date |
2012-07-11 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0957-4484;1361-6528; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.44 |
Times cited |
29 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 3.44; 2012 IF: 3.842 |
| Call Number |
UA @ lucian @ c:irua:100750 |
Serial |
895 |
| Permanent link to this record |
| |
|
| |
| Author |
Hamelet, S.; Casas-Cabanas, M.; Dupont, L.; Davoisne, C.; Tarascon, J.M.; Masquelier, C. |
| Title |
Existence of superstructures due to large amounts of Fe vacancies in the LiFePO4-type framework |
Type |
A1 Journal article |
| Year |
2011 |
Publication |
Chemistry of materials |
Abbreviated Journal |
Chem Mater |
| Volume |
23 |
Issue |
1 |
Pages |
32-38 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
LiFePO4 has been under intense scrutiny over the past decade because it stands as an attractive positive electrode material for the next generation of Li-ion batteries to power electric vehicles and hybrid electric vehicles, hence the importance of its thermal behavior. The reactivity of LiFePO4 with air at moderate temperatures is shown to be dependent on its particle size. For nanosized materials, a progressive displacement of Fe from the core structure leading to a composite made of nanosize Fe2O3 and highly defective, oxidized LixFeyPO4 compositions, among which the “ideal” formula LiFe2/3PO4. Herein we report, from both temperature-controlled X-ray diffraction and electronic diffraction microscopy, that these off-stoichiometry olivine-type compounds show a defect ordering resulting in the formation of a superstructure. Such a finding shows striking similarities with the temperature-driven oxidation of fayalite Fe2SiO4 (another olivine) to structurally defective laihunite, reported in the literature three decades ago. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
Washington, D.C. |
Editor |
|
| Language |
|
Wos |
000285726900007 |
Publication Date |
2010-12-14 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0897-4756;1520-5002; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
9.466 |
Times cited |
30 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 9.466; 2011 IF: 7.286 |
| Call Number |
UA @ lucian @ c:irua:105605 |
Serial |
1130 |
| Permanent link to this record |
| |
|
| |
| Author |
Masir, M.R.; Vasilopoulos, P.; Peeters, F.M. |
| Title |
Graphene in inhomogeneous magnetic fields : bound, quasi-bound and scattering states |
Type |
A1 Journal article |
| Year |
2011 |
Publication |
Journal of physics : condensed matter |
Abbreviated Journal |
J Phys-Condens Mat |
| Volume |
23 |
Issue |
31 |
Pages |
315301,1-315301,14 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
The electron states in graphene-based magnetic dot and magnetic ring structures and combinations of both are investigated. The corresponding spectra are studied as a function of the radii, the strengths of the inhomogeneous magnetic field and of a uniform background field, the strength of an electrostatic barrier and the angular momentum quantum number. In the absence of an external magnetic field we have only long-lived quasi-bound and scattering states and we assess their influence on the density of states. In addition, we consider elastic electron scattering by a magnetic dot, whose average B vanishes, and show that the Hall and longitudinal resistivities, as a function of the Fermi energy, exhibit a pronounced oscillatory structure due to the presence of quasi-bound states. Depending on the dot parameters this oscillatory structure differs substantially for energies below and above the first Landau level. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
|
Place of Publication |
London |
Editor |
|
| Language |
|
Wos |
000293008900002 |
Publication Date |
2011-07-16 |
| 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 |
2.649 |
Times cited |
38 |
Open Access |
|
| Notes |
; This work was supported by the European Science Foundation (ESF) under the EUROCORES Program EuroGRAPHENE, the Canadian NSERC grant no. OGP0121756 and the Belgian Science Policy (IAP). We acknowledge discussions and correspondence with Professor A Matulis. ; |
Approved |
Most recent IF: 2.649; 2011 IF: 2.546 |
| Call Number |
UA @ lucian @ c:irua:91176 |
Serial |
1372 |
| Permanent link to this record |
| |
|
| |
| Author |
Varley, J.B.; Peelaers, H.; Janotti, A.; van de Walle, C.G. |
| Title |
Hydrogenated cation vacancies in semiconducting oxides |
Type |
A1 Journal article |
| Year |
2011 |
Publication |
Journal of physics : condensed matter |
Abbreviated Journal |
J Phys-Condens Mat |
| Volume |
23 |
Issue |
33 |
Pages |
334212,1-334212,9 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
Using first-principles calculations we have studied the electronic and structural properties of cation vacancies and their complexes with hydrogen impurities in SnO2, In2O3 and β-Ga2O3. We find that cation vacancies have high formation energies in SnO2 and In2O3 even in the most favorable conditions. Their formation energies are significantly lower in β-Ga2O3. Cation vacancies, which are compensating acceptors, strongly interact with H impurities resulting in complexes with low formation energies and large binding energies, stable up to temperatures over 730 °C. Our results indicate that hydrogen has beneficial effects on the conductivity of transparent conducting oxides: it increases the carrier concentration by acting as a donor in the form of isolated interstitials, and by passivating compensating acceptors such as cation vacancies; in addition, it potentially enhances carrier mobility by reducing the charge of negatively charged scattering centers. We have also computed vibrational frequencies associated with the isolated and complexed hydrogen, to aid in the microscopic identification of centers observed by vibrational spectroscopy. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
London |
Editor |
|
| Language |
|
Wos |
000294060600014 |
Publication Date |
2011-08-04 |
| 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 |
2.649 |
Times cited |
125 |
Open Access |
|
| Notes |
; We gratefully acknowledge useful discussions with M D Mc-Cluskey, O Bierwagen and J Speck. The work was supported by the NSF MRSEC Program (DMR05-20415), the Flemish Science Foundation (FWO-VI), the Belgian American Educational Foundation, and by Saint-Gobain Research, and made use of computing facilities at CNSI (NSF grant No. CHE-0321368), TeraGrid and TACC (NSF grant No. DMR070072N), and NERSC (DOE Office of Science Contract No. DE-AC02-05CH11231). ; |
Approved |
Most recent IF: 2.649; 2011 IF: 2.546 |
| Call Number |
UA @ lucian @ c:irua:92415 |
Serial |
1534 |
| Permanent link to this record |
| |
|
| |
| Author |
Schryvers, D.; Ma, Y. |
| Title |
In-situ TEM study of the Ni5Al3 to B2 + L12 decomposition in Ni65Al35 |
Type |
A1 Journal article |
| Year |
1995 |
Publication |
Materials letters |
Abbreviated Journal |
Mater Lett |
| Volume |
23 |
Issue |
|
Pages |
105-111 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
Homogenised and quenched Ni65Al35 samples were heated and studied in situ in a CM20 electron microscope up to 900 degrees C. The Ni5Al3 phase first forming around 550 degrees C in the quenched L1(0) microtwinned martensite starts to decompose around 800 degrees C yielding B2 precipitates in a twinned L1(2) matrix. The latter twinning is a remainder of the microtwinning in the original room temperature martensite. Also the crystallographic relations between precipitates and matrix can be traced back to the original formation of twinned martensite plates within the austenite. Some aspects of the dynamics of the process are discussed on the basis of snap shots and video recordings. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
Amsterdam |
Editor |
|
| Language |
|
Wos |
A1995QW53500020 |
Publication Date |
2002-07-25 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0167-577X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.489 |
Times cited |
5 |
Open Access |
|
| Notes |
|
Approved |
no |
| Call Number |
UA @ lucian @ c:irua:13166 |
Serial |
1585 |
| Permanent link to this record |
| |
|
| |
| Author |
He, Z.; Maurice, J.-L.; Gohier, A.; Lee, C.S.; Pribat, D.; Cojocaru, C.S. |
| Title |
Iron catalysts for the growth of carbon nanofibers : Fe, Fe3C or both? |
Type |
A1 Journal article |
| Year |
2011 |
Publication |
Chemistry of materials |
Abbreviated Journal |
Chem Mater |
| Volume |
23 |
Issue |
24 |
Pages |
5379-5387 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
Iron is a widely used catalyst for the growth of carbon nanotubes (CNTs) or carbon nanofibers (CNFs) by catalytic chemical vapor deposition. However, both Fe and FeC compounds (generally, Fe3C) have been found to catalyze the growth of CNTs/CNFs, and a comparison study of their respective catalytic activities is still missing. Furthermore, the control of the crystal structure of iron-based catalysts, that is α-Fe or Fe3C, is still a challenge, which not only obscures our understanding of the growth mechanisms of CNTs/CNFs, but also complicates subsequent procedures, such as the removal of catalysts for better industrial applications. Here, we show a partial control of the phase of iron catalysts (α-Fe or Fe3C), obtained by varying the growth temperatures during the synthesis of carbon-based nanofibers/nanotubes in a plasma-enhanced chemical vapor deposition reactor. We also show that the structure of CNFs originating from Fe3C is bamboo-type, while that of CNFs originating from Fe is not. Moreover, we directly compare the growth rates of carbon-based nanofibers/nanotubes during the same experiments and find that CNFs/CNTs grown by α-Fe nanoparticles are longer than CNFs grown from Fe3C nanoparticles. The influence of the type of catalyst on the growth of CNFs is analyzed and the corresponding possible growth mechanisms, based on the different phases of the catalysts, are discussed. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
Washington, D.C. |
Editor |
|
| Language |
|
Wos |
000298197300014 |
Publication Date |
2011-11-10 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0897-4756;1520-5002; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
9.466 |
Times cited |
91 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 9.466; 2011 IF: 7.286 |
| Call Number |
UA @ lucian @ c:irua:94297 |
Serial |
1748 |
| Permanent link to this record |
| |
|
| |
| Author |
Hervieu, M.; Damay, F.; Poienar, M.; Elkaim, E.; Rouquette, J.; Abakumov, A.M.; Van Tendeloo, G.; Maignan, A.; Martin, C. |
| Title |
Nanostructures in LuFe2O4+\delta |
Type |
A1 Journal article |
| Year |
2013 |
Publication |
Solid state sciences |
Abbreviated Journal |
Solid State Sci |
| Volume |
23 |
Issue |
|
Pages |
26-34 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
A LuFe2O4+delta sample, previously characterized by X-ray synchrotron and neutron diffraction, has been studied by electron microscopy techniques, in order to get a precise description of its micro- and nanostructures at room temperature. The X-ray synchrotron data vs. temperature show that the monoclinic distortion is associated with the charge ordering; this distortion results in elongated twinning domains, which enhance the complexity of the microstructural state at room temperature. The structural modulation associated with oxygen excess is observed in large domains inside a non modulated matrix, in contrast with the modulations associated with the charge ordering of the Fe2+ and Fe3+ species, which are mostly short-range. The investigation of the nature and density of defects in the sample shows that they are nano-scaled, preserving the regularity of the layer stacking mode, and limited to the formation of one- or two-units large stacking faults, associated with gliding mechanisms. Based on these observations, an original description of the LuFe2O4 ferrite structure, through puckered [LuO4](infinity) sandwiching [Fe-2](infinity) layers, is proposed. (C) 2013 Elsevier Masson SAS. All rights reserved. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
Amsterdam |
Editor |
|
| Language |
|
Wos |
000324156200005 |
Publication Date |
2013-06-13 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1293-2558; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
1.811 |
Times cited |
7 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 1.811; 2013 IF: 1.679 |
| Call Number |
UA @ lucian @ c:irua:111196 |
Serial |
2276 |
| Permanent link to this record |
| |
|
| |
| Author |
Gélard, J.; Jehanathan, N.; Roussel, H.; Gariglio, S.; Lebedev, O.I.; Van Tendeloo, G.; Dubourdieu, C. |
| Title |
Off-stoichiometry effects on the crystalline and defect structure of hexagonal manganite REMnO3 films (RE = Y, Er, Dy) |
Type |
A1 Journal article |
| Year |
2011 |
Publication |
Chemistry of materials |
Abbreviated Journal |
Chem Mater |
| Volume |
23 |
Issue |
5 |
Pages |
1232-1238 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
The crystalline and defect structure of epitaxial hexagonal RExMnyO3 (RE = Er, Dy) films with varying cationic composition was investigated by X-ray diffraction and transmission electron microscopy. The films are composed of a strained layer at the interface with the substrate and of a relaxed layer on top of it. The critical thickness is of 10 to 25 nm. For Mn-rich films (or RE deficient), an off-stoichiometric composition maintaining the hexagonal LuMnO3-type structure is stabilized over a large range of the RE/Mn ratio (0.72−1.00), with no Mn-rich secondary phases observed. A linear dependence of the out-of-plane lattice parameter with RE/Mn is observed in this range. Out-of-phase boundary (OPB) extended defects are observed in all films and exhibit a local change in stoichiometry. Such a large solubility limit in the RE deficient region points toward the formation of vacancies on the RE site (RExMnO3−δ, with 0.72 ≤ x < 1), a phenomenon that is encountered in perovskite manganites such as LaxMnO3−δ (x < 1) and that may strongly impact the physical properties of hexagonal manganites. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
Washington, D.C. |
Editor |
|
| Language |
|
Wos |
000287767200022 |
Publication Date |
2011-02-03 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0897-4756;1520-5002; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
9.466 |
Times cited |
17 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 9.466; 2011 IF: 7.286 |
| Call Number |
UA @ lucian @ c:irua:88649 |
Serial |
2430 |
| Permanent link to this record |
| |
|
| |
| Author |
Geim, A.K.; Grigorieva, I.V.; Lok, J.G.S.; Maan, J.C.; Dubonos, S.V.; Li, X.Q.; Peeters, F.M.; Nazarov, Y.V. |
| Title |
Precision magnetometry on a submicron scale: magnetisation of superconducting quantum dots |
Type |
A1 Journal article |
| Year |
1998 |
Publication |
Superlattices and microstructures |
Abbreviated Journal |
Superlattice Microst |
| Volume |
23 |
Issue |
1 |
Pages |
151-160 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
We report on magnetisation of individual superconducting particles with size down to 0.1 micron. The non-invasive access to properties of such small objects has become possible using submicron Hall probes which detect a local magnetic field and work effectively as micro-fluxmeters similar to, e.g., SQUIDs but with an effective detection loop of only about a square micron. We have found that the spatial confinement of superconductivity in a small volume gives rise to dramatic changes in thermodynamic properties of mesoscopic superconductors. (C) 1998 Academic Press Limited. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
London |
Editor |
|
| Language |
|
Wos |
000072338200025 |
Publication Date |
2002-10-06 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0749-6036; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.123 |
Times cited |
12 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 2.123; 1998 IF: 0.831 |
| Call Number |
UA @ lucian @ c:irua:95842 |
Serial |
2691 |
| Permanent link to this record |
| |
|
| |
| Author |
Van Gaens, W.; Bogaerts, A. |
| Title |
Reaction pathways of biomedically active species in an Ar plasma jet |
Type |
A1 Journal article |
| Year |
2014 |
Publication |
Plasma sources science and technology |
Abbreviated Journal |
Plasma Sources Sci T |
| Volume |
23 |
Issue |
3 |
Pages |
035015-35027 |
| Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
| Abstract |
In this paper we analyse the gas phase production and loss pathways for several biomedically active species, i.e. N2(A), O, O3, O2(a), N, H, HO2, OH, NO, NO2, N2O5, H2O2, HNO2 and HNO3, in an argon plasma jet flowing into an open humid air atmosphere. For this purpose, we employ a zero-dimensional reaction kinetics model to mimic the typical experimental conditions by fitting several parameters to experimentally measured values. These include ambient air diffusion, the gas temperature profile and power deposition along the jet effluent. We focus in detail on how the pathways of the biomedically active species change as a function of the position in the effluent, i.e. inside the discharge device, active plasma jet effluent and afterglow region far from the nozzle. Moreover, we demonstrate how the reaction kinetics and species production are affected by different ambient air humidities, total deposited power into the plasma and gas temperature along the jet. It is shown that the dominant pathways can drastically change as a function of the distance from the nozzle exit or experimental conditions. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
Institute of Physics |
Place of Publication |
Bristol |
Editor |
|
| Language |
|
Wos |
000337891900017 |
Publication Date |
2014-05-22 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0963-0252;1361-6595; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.302 |
Times cited |
34 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 3.302; 2014 IF: 3.591 |
| Call Number |
UA @ lucian @ c:irua:117075 |
Serial |
2820 |
| Permanent link to this record |
| |
|
| |
| Author |
Dachraoui, W.; Yang, T.; Liu, C.; Ling, G.; Hadermann, J.; Van Tendeloo, G.; Llobet, A.; Greenblatt, M. |
| Title |
Short-range layered A-site ordering in double perovskites NaLaBB'O6 (B = Mn, Fe; B' = Nb, Ta) |
Type |
A1 Journal article |
| Year |
2011 |
Publication |
Chemistry of materials |
Abbreviated Journal |
Chem Mater |
| Volume |
23 |
Issue |
9 |
Pages |
2398-2406 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
The new compounds NaLaFeTaO6, NaLaFeNbO6, NaLaMnTaO6, and NaLaMnNbO6 have been synthesized and characterized with a combination of transmission electron microscopy, X-ray powder diffraction (XRPD), neutron powder diffraction (NPD), and magnetization measurements. Through electron microscopy study, a local layered order of the A-cations has been detected without the typical occurrence of rock salt order at the B-cation site. Satellite reflections in the electron diffraction related to the local layered order are not visible on the XRPD or NPD patterns. The occurrence of local layered order is supported by pair distribution function analysis, which also reveals the presence of uncorrelated displacements of the Nb and Ta cations. The octahedra are tilted according to the system a−b+a−, and the coordinates were refined from XRPD and NPD with a disordered cation distribution in the space group Pnma. The magnetic exchange interactions in NaLaFeTaO6 and NaLaFeNbO6 are antiferromagnetic, while they are ferromagnetic in NaLaMnTaO6 and NaLaMnNbO6. Long-range magnetic ordering is not observed down to 4 K for any of the compositions. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
Washington, D.C. |
Editor |
|
| Language |
|
Wos |
000290063600016 |
Publication Date |
2011-04-14 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0897-4756;1520-5002; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
9.466 |
Times cited |
14 |
Open Access |
|
| Notes |
Esteem 026019 |
Approved |
Most recent IF: 9.466; 2011 IF: 7.286 |
| Call Number |
UA @ lucian @ c:irua:89944 |
Serial |
2996 |
| Permanent link to this record |
| |
|
| |
| Author |
Hadermann, J.; Abakumov, A.M.; Turner, S.; Hafideddine, Z.; Khasanova, N.R.; Antipov, E.V.; Van Tendeloo, G. |
| Title |
Solving the structure of Li ion battery materials with precession electron diffraction : application to Li2CoPo4F |
Type |
A1 Journal article |
| Year |
2011 |
Publication |
Chemistry of materials |
Abbreviated Journal |
Chem Mater |
| Volume |
23 |
Issue |
15 |
Pages |
3540-3545 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
The crystal structure of the Li2CoPO4F high-voltage cathode for Li ion rechargeable batteries has been completely solved from precession electron diffraction (PED) data, including the location of the Li atoms. The crystal structure consists of infinite chains of CoO4F2 octahedra sharing common edges and linked into a 3D framework by PO4 tetrahedra. The chains and phosphate anions together delimit tunnels filled with the Li atoms. This investigation demonstrates that PED can be successfully applied for obtaining structural information on a variety of Li-containing electrode materials even from single micrometer-sized crystallites. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
Washington, D.C. |
Editor |
|
| Language |
|
Wos |
000293357100019 |
Publication Date |
2011-07-11 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0897-4756;1520-5002; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
9.466 |
Times cited |
46 |
Open Access |
|
| Notes |
Fwo; Bof |
Approved |
Most recent IF: 9.466; 2011 IF: 7.286 |
| Call Number |
UA @ lucian @ c:irua:90357 |
Serial |
3053 |
| Permanent link to this record |
| |
|
| |
| Author |
Kozák, T.; Bogaerts, A. |
| Title |
Splitting of CO2 by vibrational excitation in non-equilibrium plasmas : a reaction kinetics model |
Type |
A1 Journal article |
| Year |
2014 |
Publication |
Plasma sources science and technology |
Abbreviated Journal |
Plasma Sources Sci T |
| Volume |
23 |
Issue |
4 |
Pages |
045004 |
| Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
| Abstract |
We present a zero-dimensional kinetic model of CO2 splitting in non-equilibrium plasmas. The model includes a description of the CO2 vibrational kinetics (25 vibrational levels up to the dissociation limit of the molecule), taking into account state-specific VT and VV relaxation reactions and the effect of vibrational excitation on other chemical reactions. The model is applied to study the reaction kinetics of CO2 splitting in an atmospheric-pressure dielectric barrier discharge (DBD) and in a moderate-pressure microwave discharge. The model results are in qualitative agreement with published experimental works. We show that the CO2 conversion and its energy efficiency are very different in these two types of discharges, which reflects the important dissociation mechanisms involved. In the microwave discharge, excitation of the vibrational levels promotes efficient dissociation when the specific energy input is higher than a critical value (2.0 eV/molecule under the conditions examined). The calculated energy efficiency of the process has a maximum of 23%. In the DBD, vibrationally excited levels do not contribute significantly to the dissociation of CO2 and the calculated energy efficiency of the process is much lower (5%). |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
Institute of Physics |
Place of Publication |
Bristol |
Editor |
|
| Language |
|
Wos |
000345761500014 |
Publication Date |
2014-06-17 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0963-0252;1361-6595; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.302 |
Times cited |
170 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 3.302; 2014 IF: 3.591 |
| Call Number |
UA @ lucian @ c:irua:117398 |
Serial |
3108 |
| Permanent link to this record |
| |
|
| |
| Author |
Rusakov, D.; Abakumov, A.M.; Yamaura, K.; Belik, A.A.; Van Tendeloo, G.; Takayama-Muromachi, E. |
| Title |
Structural evolution of the BiFeO3-LaFeO3 system |
Type |
A1 Journal article |
| Year |
2011 |
Publication |
Chemistry of materials |
Abbreviated Journal |
Chem Mater |
| Volume |
23 |
Issue |
2 |
Pages |
285-292 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
The (1 − x)BiFeO3−xLaFeO3 system has been investigated and characterized by room-temperature and high-temperature laboratory and synchrotron powder X-ray diffraction, electron diffraction, high-resolution transmission electron microscopy, differential scanning calorimetry, and magnetization measurements. At room temperature, the ferroelectric R3c phase is observed for 0.0 ≤ x ≤ 0.10. The PbZrO3-related √2ap × 2√2ap × 4ap superstructure (where ap is the parameter of the cubic perovskite subcell) is observed for Bi0.82La0.18FeO3, while an incommensurately modulated phase is formed for 0.19 ≤ x ≤ 0.30 with the √2ap × 2ap × √2ap basic unit cell. The GdFeO3-type phase with space group Pnma (√2ap × 2ap × √2ap) is stable at 0.50 ≤ x ≤ 1. Bi0.82La0.18FeO3 has no detectable homogeneity range (space group Pnam, a = 5.6004(1) Å, b = 11.2493(3) Å, c = 15.6179(3) Å). The incommensurately modulated Bi0.75La0.25FeO3 structure was solved from synchrotron X-ray powder diffraction data (Imma(00γ)s00 superspace group, a = 5.5956(1) Å, b = 7.8171(1) Å, c = 5.62055(8) Å, q = 0.4855(4)c*, RP = 0.023, RwP = 0.033). In this structure, cooperative displacements of the Bi and O atoms occur, which order within the (AO) (where A = Bi, La) layers, resulting in an antipolar structure. Local fluctuations of the intralayer antipolar ordering are compensated by an interaction with the neighboring (AO) layers. A coupling of the antipolar displacements with the cooperative tilting distortion of the perovskite octahedral framework is proposed as the origin of the incommensurability. All the phases transform to the GdFeO3-type structure at high temperatures. Bi0.82La0.18FeO3 shows an intermediate PbZrO3-type phase with √2ap × 2√2ap × 2ap (space group Pbam; a = 5.6154(2) Å, b = 11.2710(4) Å, and c = 7.8248(2) Å at 570 K). The compounds in the compositional range of 0.18 ≤ x ≤ 0.95 are canted antiferromagnets. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
Washington, D.C. |
Editor |
|
| Language |
|
Wos |
000286160800021 |
Publication Date |
2010-12-23 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0897-4756;1520-5002; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
9.466 |
Times cited |
133 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 9.466; 2011 IF: 7.286 |
| Call Number |
UA @ lucian @ c:irua:88650 |
Serial |
3236 |
| Permanent link to this record |
| |
|
| |
| Author |
Croitoru, M.D.; Shanenko, A.A.; Peeters, F.M. |
| Title |
Superconducting nanowires: quantum-confinement effect on the critical magnetic field and supercurrent |
Type |
A1 Journal article |
| Year |
2009 |
Publication |
International journal of modern physics: B: condensed matter physics, statistical physics, applied physics
T2 – 32nd International Workshop on Condensed Matter Theories, Aug 12-19, 2008, Loughborough Univ, Loughborough, England |
Abbreviated Journal |
Int J Mod Phys B |
| Volume |
23 |
Issue |
20-21 |
Pages |
4257-4268 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT); Electron microscopy for materials research (EMAT) |
| Abstract |
We study the effect of electron confinement on the superconducting-to-normal phase transition driven by a magnetic field and/or on the current-carrying state of the superconducting condensate in nanowires. Our investigation is based on a self-consistent numerical solution of the Bogoliubov-de Gennes equations. We show that in a parallel magnetic field and/or in the presence of supercurrent the transition from superconducting to normal phase occurs as a cascade of discontinuous jumps in the superconducting order parameter for diameters D < 10 divided by 15 nm at T = 0. The critical magnetic field exhibits quantum-size oscillations with pronounced resonant enhancements. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
World scientific |
Place of Publication |
Singapore |
Editor |
|
| Language |
|
Wos |
000274525500026 |
Publication Date |
2009-09-23 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0217-9792;1793-6578; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
0.736 |
Times cited |
1 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 0.736; 2009 IF: 0.408 |
| Call Number |
UA @ lucian @ c:irua:95673 |
Serial |
3362 |
| Permanent link to this record |
| |
|
| |
| Author |
Tan, H.; Lebedev, O.I.; McLaughlin, A.C.; Van Tendeloo, G. |
| Title |
The superstructure and superconductivity of Ru1222 based RuSr2Gd2-x-yYyCexCu2O10-\delta compounds |
Type |
A1 Journal article |
| Year |
2010 |
Publication |
Superconductor science and technology |
Abbreviated Journal |
Supercond Sci Tech |
| Volume |
23 |
Issue |
11 |
Pages |
115013-115013,8 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
For the first time, the local structure and physical properties of Ru1222 based compounds (RuSr(2)Gd(1.4)Ce(0.6)Cu(2)O(10-delta) and RuSr(2)Gd(1.8-x)Y(0.2)CexCu(2)O(10) (x = 0.90-0.55)) have been investigated and analyzed together on the very same compounds. The Ru1222 superstructure was confirmed by TEM at a local scale and was suggested to have an orthorhombic symmetry with space group Aba2 and lattice parameters a(s) similar or equal to root 2a, b(s) similar or equal to root 2a and c(s) = c. This new Ru1222 superstructure distortion from tetragonal symmetry is proposed to have a positive correlation with the superconductivity variation of these compounds. The more the distortion towards orthorhombic symmetry, the higher the critical superconducting temperature these compounds can achieve. The T(c)(0) of RuSr(2)Gd(1.8-x)Y(0.2)Ce(x)Cu(2)O(10-delta) (x = 0.85-0.55) increases monotonically from 4 to 16 K when x decreases from 0.85 to 0.70, then RuSr(2)Gd(2)Cu(2)O(8) defects emerge and the T(c) decreases with decreasing x. Ru1212 defects are observed to intergrow epitaxially with the Ru1222 structure as lamellas along the c-axis in RuSr(2)Gd(1.4)Ce(0.6)Cu(2)O(10-delta). Although Ru1212 is a superconductor, the intergrowth severely restrains its superconductivity. |
| Address |
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| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
Bristol |
Editor |
|
| Language |
|
Wos |
000284308000013 |
Publication Date |
2010-10-09 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0953-2048;1361-6668; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.878 |
Times cited |
1 |
Open Access |
|
| Notes |
Fwo; Esteem 026019 |
Approved |
Most recent IF: 2.878; 2010 IF: 2.402 |
| Call Number |
UA @ lucian @ c:irua:95553 |
Serial |
3385 |
| Permanent link to this record |
| |
|
| |
| Author |
Hao, Y.L.; Djotyan, A.P.; Avetisyan, A.A.; Peeters, F.M. |
| Title |
D- shallow donor near a semiconductor-metal and a semiconductor-dielectric interface |
Type |
A1 Journal article |
| Year |
2011 |
Publication |
Journal of physics : condensed matter |
Abbreviated Journal |
J Phys-Condens Mat |
| Volume |
23 |
Issue |
11 |
Pages |
115303,1-115313,9 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
The ground state energy and the extent of the wavefunction of a negatively charged donor (D − ) located near a semiconductormetal or a semiconductordielectric interface are obtained. We apply the effective mass approximation and use a variational two-electron wavefunction that takes into account the influence of all image charges that arise due to the presence of the interface, as well as the correlation between the two electrons bound to the donor. For a semiconductormetal interface, the D − binding energy is enhanced for donor positions d > 1.5aB (aB is the effective Bohr radius) due to the additional attraction of the electrons with their images. When the donor approaches the interface (i.e. d < 1.5aB) the D − binding energy drops and eventually it becomes unbound. For a semiconductordielectric (or a semiconductorvacuum) interface the D − binding energy is reduced for any donor position as compared to the bulk case and the system becomes rapidly unbound when the donor approaches the interface. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
London |
Editor |
|
| Language |
|
Wos |
000287969200013 |
Publication Date |
2011-03-04 |
| 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 |
2.649 |
Times cited |
5 |
Open Access |
|
| Notes |
; This work was supported by the Belgian Science Policy (IAP) and the Brazilian Science Foundation CNPq. One of us (AAA) was supported by a fellowship from the Belgian Federal Science Policy Office (IAP). ; |
Approved |
Most recent IF: 2.649; 2011 IF: 2.546 |
| Call Number |
UA @ lucian @ c:irua:88828 |
Serial |
3528 |
| Permanent link to this record |
| |
|
| |
| Author |
Eckert, M.; Mortet, V.; Zhang, L.; Neyts, E.; Verbeeck, J.; Haenen, ken; Bogaerts, A. |
| Title |
Theoretical investigation of grain size tuning during prolonged bias-enhanced nucleation |
Type |
A1 Journal article |
| Year |
2011 |
Publication |
Chemistry of materials |
Abbreviated Journal |
Chem Mater |
| Volume |
23 |
Issue |
6 |
Pages |
1414-1423 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
| Abstract |
In this paper, the effects of prolonged bias-enhanced nucleation (prolonged BEN) on the growth mechanisms of diamond are investigated by molecular dynamics (MD) and combined MD-Metropolis Monte Carlo (MD-MMC) simulations. First, cumulative impacts of CxHy+ and Hx+ on an a-C:H/nanodiamond composite were simulated; second, nonconsecutive impacts of the dominant ions were simulated in order to understand the observed phenomena in more detail. As stated in the existing literature, the growth of diamond structures during prolonged BEN is a process that takes place below the surface of the growing film. The investigation of the penetration behavior of CxHy+ and Hx+ species shows that the carbon-containing ions remain trapped within this amorphous phase where they dominate mechanisms like precipitation of sp3 carbon clusters. The H+ ions, however, penetrate into the crystalline phase at high bias voltages (>100 V), destroying the perfect diamond structure. The experimentally measured reduction of grain sizes at high bias voltage, reported in the literature, might thus be related to penetrating H+ ions. Furthermore, the CxHy+ ions are found to be the most efficient sputtering agents, preventing the build up of defective material. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
Washington, D.C. |
Editor |
|
| Language |
|
Wos |
000288291400011 |
Publication Date |
2011-02-23 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0897-4756;1520-5002; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
9.466 |
Times cited |
9 |
Open Access |
|
| Notes |
Iwt; Fwo; Esteem 026019; Iap |
Approved |
Most recent IF: 9.466; 2011 IF: 7.286 |
| Call Number |
UA @ lucian @ c:irua:87642 |
Serial |
3605 |
| Permanent link to this record |
| |
|
| |
| Author |
Idrissi, H.; Wang, B.; Colla, M.S.; Raskin, J.P.; Schryvers, D.; Pardoen, T. |
| Title |
Ultrahigh strain hardening in thin palladium films with nanoscale twins |
Type |
A1 Journal article |
| Year |
2011 |
Publication |
Advanced materials |
Abbreviated Journal |
Adv Mater |
| Volume |
23 |
Issue |
18 |
Pages |
2119-2122 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
Nanocrystalline Pd thin films containing coherent growth twin boundaries are deformed using on-chip nanomechanical testing. A large work-hardening capacity is measured. The origin of the observed behavior is unraveled using transmission electron microscopy and shows specific dislocations and twin boundaries interactions. The results indicate the potential for large strength and ductility balance enhancement in Pd films, as needed in membranes for H technologies. |
| Address |
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| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
Weinheim |
Editor |
|
| Language |
|
Wos |
000291164200013 |
Publication Date |
2011-04-04 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0935-9648; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
19.791 |
Times cited |
57 |
Open Access |
|
| Notes |
Iap |
Approved |
Most recent IF: 19.791; 2011 IF: 13.877 |
| Call Number |
UA @ lucian @ c:irua:90103 |
Serial |
3794 |
| Permanent link to this record |
| |
|
| |
| Author |
Kazakov, S.M.; Abakumov, A.M.; Perz-Mato, J.M.; Ovchinnikov, A.V.; Roslova, M.V.; Boltalin, A.I.; Morozov, I.V.; Antipov, E.V.; Van Tendeloo, G. |
| Title |
Uniform patterns of Fe-vacancy ordering in the Kx(Fe,Co)2-ySe2 superconductors |
Type |
A1 Journal article |
| Year |
2011 |
Publication |
Chemistry of materials |
Abbreviated Journal |
Chem Mater |
| Volume |
23 |
Issue |
19 |
Pages |
4311-4316 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
The Fe-vacancy ordering patterns in the superconducting KxFe2ySe2 and nonsuperconducting Kx(Fe,Co)2ySe2 samples have been investigated by electron diffraction and high angle annular dark field scanning transmission electron microscopy. The Fe-vacancy ordering occurs in the ab plane of the parent ThCr2Si2-type structure, demonstrating two types of patterns. Superstructure I retains the tetragonal symmetry and can be described with the aI = bI = as√5 (as is the unit cell parameter of the parent ThCr2Si2-type structure) supercell and I4/m space group. Superstructure II reduces the symmetry to orthorhombic with the aII = as√2, bII = 2as√2 supercell and the Ibam space group. This type of superstructure is observed for the first time in KxFe2ySe2. The Fe-vacancy ordering is inhomogeneous: the disordered areas interleave with the superstructures I and II in the same crystallite. The observed superstructures represent the compositionally dependent uniform ordering patterns of two species (the Fe atoms and vacancies) on a square lattice. More complex uniform ordered configurations, including compositional stripes, can be predicted for different chemical compositions of the KxFe2ySe2 (0 < y < 0.5) solid solutions. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
|
Place of Publication |
Washington, D.C. |
Editor |
|
| Language |
|
Wos |
000295487800005 |
Publication Date |
2011-09-13 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0897-4756;1520-5002; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
9.466 |
Times cited |
20 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 9.466; 2011 IF: 7.286 |
| Call Number |
UA @ lucian @ c:irua:92805 |
Serial |
3810 |
| Permanent link to this record |
| |
|
| |
| Author |
Rakhimov, K.Y.; Chaves, A.; Farias, G.A.; Peeters, F.M. |
| Title |
Wavepacket scattering of Dirac and Schrödinger particles on potential and magnetic barriers |
Type |
A1 Journal article |
| Year |
2011 |
Publication |
Journal of physics : condensed matter |
Abbreviated Journal |
J Phys-Condens Mat |
| Volume |
23 |
Issue |
27 |
Pages |
275801,1-275801,16 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
We investigate the dynamics of a charged particle moving in a graphene layer and in a two-dimensional electron gas, where it obeys the Dirac and the Schrödinger equations, respectively. The charge carriers are described as Gaussian wavepackets. The dynamics of the wavepackets is studied numerically by solving both quantum-mechanical and relativistic equations of motion. The scattering of such wavepackets by step-like magnetic and potential barriers is analysed for different values of wavepacket energy and width. We find: (1) that the average position of the wavepacket does not coincide with the classical trajectory, and (2) that, for slanted incidence, the path of the centre of mass of the wavepacket does not have to penetrate the barrier during the scattering process. Trembling motion of the charged particle in graphene is observed in the absence of an external magnetic field and can be enhanced by a substrate-induced mass term. |
| Address |
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| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
London |
Editor |
|
| Language |
|
Wos |
000291993600009 |
Publication Date |
2011-06-18 |
| 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 |
2.649 |
Times cited |
32 |
Open Access |
|
| Notes |
; Discussions with A Matulis are gratefully acknowledged. KR is beneficiary of a mobility grant from the Belgian Federal Science Policy Office, co-funded by the European Commission and was supported in part by a grant of the Third World Academy of Sciences (ref. 09-188 RG/PHYS/AS-I). In addition, this work was financially supported by CNPq, under contract NanoBioEstruturas 555183/2005-0, PRONEX/FUNCAP, CAPES, the Bilateral programme between Flanders and Brazil, the joint project CNPq-FWO, the Belgian Science Policy (IAP) and the Flemish Science Foundation (FWO-Vl). ; |
Approved |
Most recent IF: 2.649; 2011 IF: 2.546 |
| Call Number |
UA @ lucian @ c:irua:90880 |
Serial |
3908 |
| Permanent link to this record |
| |
|
| |
| Author |
Roesler, C.; Dissegna, S.; Rechac, V.L.; Kauer, M.; Guo, P.; Turner, S.; Ollegott, K.; Kobayashi, H.; Yamamoto, T.; Peeters, D.; Wang, Y.; Matsumura, S.; Van Tendeloo, G.; Kitagawa, H.; Muhler, M.; Llabres i Xamena, F.X.; Fischer, R.A. |
| Title |
Encapsulation of bimetallic metal nanoparticles into robust zirconium-based metal-organic frameworks : evaluation of the catalytic potential for size-selective hydrogenation |
Type |
A1 Journal article |
| Year |
2017 |
Publication |
Chemistry: a European journal |
Abbreviated Journal |
Chem-Eur J |
| Volume |
23 |
Issue |
15 |
Pages |
3583-3594 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
The realization of metal nanoparticles (NPs) with bimetallic character and distinct composition for specific catalytic applications is an intensively studied field. Due to the synergy between metals, most bimetallic particles exhibit unique properties that are hardly provided by the individual monometallic counterparts. However, as small-sized NPs possess high surface energy, agglomeration during catalytic reactions is favored. Sufficient stabilization can be achieved by confinement of NPs in porous support materials. In this sense, metal-organic frameworks (MOFs) in particular have gained a lot of attention during the last years; however, encapsulation of bimetallic species remains challenging. Herein, the exclusive embedding of preformed core-shell PdPt and RuPt NPs into chemically robust Zr-based MOFs is presented. Microstructural characterization manifests partial retention of the core-shell systems after successful encapsulation without harming the crystallinity of the microporous support. The resulting chemically robust NP@UiO-66 materials exhibit enhanced catalytic activity towards the liquid-phase hydrogenation of nitrobenzene, competitive with commercially used Pt on activated carbon, but with superior size-selectivity for sterically varied substrates. |
| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
|
Place of Publication |
Weinheim |
Editor |
|
| Language |
|
Wos |
000397502900010 |
Publication Date |
2016-12-06 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0947-6539 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
5.317 |
Times cited |
13 |
Open Access |
Not_Open_Access |
| Notes |
; This work is supported by the Cluster of Excellence RESOLV (EXC 1069) funded by the Deutsche Forschungsgemeinschaft (DFG). ; |
Approved |
Most recent IF: 5.317 |
| Call Number |
UA @ lucian @ c:irua:142485 |
Serial |
4653 |
| Permanent link to this record |
