Records |
Author |
Tan, H. |
Title |
From EELS to oxidation state mapping : an investigation into oxidation state mapping of transition metals with electron energy-loss spectroscopy |
Type |
Doctoral thesis |
Year |
2012 |
Publication |
|
Abbreviated Journal |
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Volume |
|
Issue |
|
Pages |
|
Keywords |
Doctoral thesis; Electron microscopy for materials research (EMAT) |
Abstract |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Antwerpen |
Editor |
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Language |
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Wos |
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Publication Date |
0000-00-00 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
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ISBN |
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Additional Links |
UA library record |
Impact Factor |
|
Times cited |
|
Open Access |
|
Notes |
|
Approved |
Most recent IF: NA |
Call Number |
UA @ lucian @ c:irua:96030 |
Serial |
1280 |
Permanent link to this record |
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Author |
Bourgeois, J.; Hervieu, M.; Poienar, M.; Abakumov, A.M.; Elkaïm, E.; Sougrati, M.T.; Porcher, F.; Damay, F.; Rouquette, J.; Van Tendeloo, G.; Maignan, A.; Haines, J.; Martin, C.; |
Title |
Evidence of oxygen-dependent modulation in LuFe2O4 |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
85 |
Issue |
6 |
Pages |
064102-064120,10 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
A polycrystalline sample of LuFe2O4 has been investigated by means of powder synchrotron x-ray and neutron diffraction and transmission electron microscopy (TEM), along with Mössbauer spectroscopy and transport and magnetic properties. A monoclinic distortion is unambiguously evidenced, and the crystal structure is refined in the monoclinic C2/m space group [aM = 5.9563(1) Å, bM = 3.4372(1) Å, cM = 8.6431(1) Å, β = 103.24(1)°]. Along with the previously reported modulations distinctive of the charge-ordering (CO) of the iron species, a new type of incommensurate order is observed, characterized by a vector q⃗1 = α1a⃗M* + γ1c⃗M* (with α1 ≅ 0.55, γ1 ≅ 0.13). In situ heating TEM observations from 300 to 773 K confirm that the satellites associated with q⃗1 vanish completely, only at a temperature significantly higher than the CO temperature. This incommensurate modulation has a displacive character and corresponds primarily to a transverse displacive modulation wave of the Lu cations position, as revealed by the high resolution, high angle annular dark field scanning TEM images and in agreement with synchrotron data refinements. Analyses of vacuum-annealed samples converge toward the hypothesis of a new ordering mechanism, associated with a tiny oxygen deviation from the O4 stoichiometry. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000299896900003 |
Publication Date |
2012-02-06 |
Series Editor |
|
Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
24 |
Open Access |
|
Notes |
Hercules |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
Call Number |
UA @ lucian @ c:irua:95042 |
Serial |
1095 |
Permanent link to this record |
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|
Author |
Brück, S.; Paul, M.; Tian, H.; Müller, A.; Kufer, D.; Praetorius, C.; Fauth, K.; Audehm, P.; Goering, E.; Verbeeck, J.; Van Tendeloo, G.; Sing, M.; Claessen, R.; |
Title |
Magnetic and electronic properties of the interface between half metallic Fe3O4 and semiconducting ZnO |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Applied physics letters |
Abbreviated Journal |
Appl Phys Lett |
Volume |
100 |
Issue |
8 |
Pages |
081603-081603,4 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
We have investigated the magnetic depth profile of an epitaxial Fe3O4 thin film grown directly on a semiconducting ZnO substrate by soft x-ray resonant magnetic reflectometry (XRMR) and electron energy loss spectroscopy (EELS). Consistent chemical profiles at the interface between ZnO and Fe3O4 are found from both methods. Valence selective EELS and XRMR reveal independently that the first monolayer of Fe at the interface between ZnO and Fe3O4 contains only Fe3+ ions. Besides this narrow 2.5 Å interface layer, Fe3O4 shows magnetic bulk properties throughout the whole film making highly efficient spin injection in this system feasible. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
American Institute of Physics |
Place of Publication |
New York, N.Y. |
Editor |
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Language |
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Wos |
000300711200014 |
Publication Date |
2012-02-22 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0003-6951; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.411 |
Times cited |
12 |
Open Access |
|
Notes |
The authors thank E. Pellegrin for helpful comments and S. Macke for help with the software REMAGX. S.B. acknowledges financial support by the HZB, Berlin, and the Australian Government via Grant No. RM08550. H.T. acknowledges funding from GOA project “XANES meets ELNES,” J.V. and G.V.T. acknowledge funding from the European Research Council under Grant No. 46791-COUN-TATOMS. The authors acknowledge financial support by the DFG through Forschergruppe FOR 1162. |
Approved |
Most recent IF: 3.411; 2012 IF: 3.794 |
Call Number |
UA @ lucian @ c:irua:95041UA @ admin @ c:irua:95041 |
Serial |
1860 |
Permanent link to this record |
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Author |
Goris, B.; van Huis, M.A.; Bals, S.; Zandbergen, H.W.; Manna, L.; Van Tendeloo, G. |
Title |
Thermally induced structural and morphological changes of CdSe/CdS octapods |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Small |
Abbreviated Journal |
Small |
Volume |
8 |
Issue |
6 |
Pages |
937-942 |
Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
Abstract |
Branched nanostructures are of great interest because of their promising optical and electronic properties. For successful and reliable integration in applications such as photovoltaic devices, the thermal stability of the nanostructures is of major importance. Here the different domains (CdSe cores, CdS pods) of the heterogeneous octapods are shown to have different thermal stabilities, and heating is shown to induce specific shape changes. The octapods are heated from room temperature to 700 °C, and investigated using (analytical and tomographic) transmission electron microscopy (TEM). At low annealing temperatures, pure Cd segregates in droplets at the outside of the octapods, indicating non-stochiometric composition of the octapods. Furthermore, the tips of the pods lose their faceting and become rounded. Further heating to temperatures just below the sublimation temperature induces growth of the zinc blende core at the expense of the wurtzite pods. At higher temperatures, (500700 °C), sublimation of the octapods is observed in real time in the TEM. Three-dimensional tomographic reconstructions reveal that the four pods pointing into the vacuum have a lower thermal stability than the four pods that are in contact with the support. |
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 |
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Language |
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Wos |
000301718800021 |
Publication Date |
2012-01-31 |
Series Editor |
|
Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
1613-6810; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
8.643 |
Times cited |
20 |
Open Access |
|
Notes |
Fwo; Esteem 026019 |
Approved |
Most recent IF: 8.643; 2012 IF: 7.823 |
Call Number |
UA @ lucian @ c:irua:95040 |
Serial |
3633 |
Permanent link to this record |
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Author |
Ramezanipour, F.; Greedan, J.E.; Siewenie, J.; Donaberger, R.L.; Turner, S.; Botton, G.A. |
Title |
A vacancy-disordered, oxygen-deficient perovskite with long-range magnetic ordering : local and average structures and magnetic properties of Sr2Fe1.5Cr0.5O5 |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Inorganic chemistry |
Abbreviated Journal |
Inorg Chem |
Volume |
51 |
Issue |
4 |
Pages |
2638-2644 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
The local and average crystal structures and magnetic properties of the oxygen-deficient perovskite Sr2Fe1.5Cr0.5O5+y were studied using powder X-ray and neutron diffraction, neutron-pair distribution function analysis, and electron energy-loss spectroscopy. This material crystallizes in the cubic Pm3̅m space group, with a = 3.94491(14) Å. The oxygen vacancies are distributed randomly throughout the perovskite-type structure, and the average coordination number of the Fe(Cr) sites is 5. Refinement of the neutron diffraction data indicates y 0.05. This is in discordance with an earlier report on a material with the same nominal composition and cell constant. Electron energy-loss Cr L2,3-edge spectroscopy shows that Cr3+ is present, which is also contrary to previous speculation. Neutron-pair distribution function studies show that a brownmillerite-like model involving ordered vacancies and alternating octahedral and tetrahedral coordination at the metal sites, gives a better description of the local structure out to 5 Å. A remarkable phenomenon determined by neutron diffraction in Sr2Fe1.5Cr0.5O5 is the occurrence of a long-range G-type antiferromagnetic ordering with Tc ≈ 565 K because cubic oxygen-deficient perovskites with B-site disorder usually do not undergo transitions to magnetically ordered states. The observation of long-range antiferromagnetic order and the Tc value are in accordance with previous Mössbauer spectroscopic studies. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Easton, Pa |
Editor |
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Language |
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Wos |
000300466300079 |
Publication Date |
2012-01-30 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
|
Edition |
|
ISSN |
0020-1669;1520-510X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
4.857 |
Times cited |
12 |
Open Access |
|
Notes |
Fwo |
Approved |
Most recent IF: 4.857; 2012 IF: 4.593 |
Call Number |
UA @ lucian @ c:irua:95039 |
Serial |
3828 |
Permanent link to this record |
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Author |
Lebedev, O.I.; Turner, S.; Liu, S.; Cool, P.; Van Tendeloo, G. |
Title |
New nano-architectures of mesoporous silica spheres analyzed by advanced electron microscopy |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Nanoscale |
Abbreviated Journal |
Nanoscale |
Volume |
4 |
Issue |
5 |
Pages |
1722-1727 |
Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA) |
Abstract |
Using template-containing silica microspheres as a precursor, novel ordered mesoporous silica nanoparticles with a narrow pore size distribution and high crystallinity have been synthesized by various hydrothermal merging processes. Several architectures like chains, dumbbells, triangles, squares and flowers have been discovered. The linking mechanisms of these interacting silica spheres leading to the formation of ordered nano-structures are studied by HRTEM, HAADF-STEM and electron tomography and a plausible model is presented for several merging processes. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Cambridge |
Editor |
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Language |
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Wos |
000300433700051 |
Publication Date |
2011-12-21 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2040-3364;2040-3372; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
7.367 |
Times cited |
5 |
Open Access |
|
Notes |
Fwo |
Approved |
Most recent IF: 7.367; 2012 IF: 6.233 |
Call Number |
UA @ lucian @ c:irua:95038 |
Serial |
2328 |
Permanent link to this record |
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Author |
Lu, Y.-G.; Verbeeck, J.; Turner, S.; Hardy, A.; Janssens, S.D.; De Dobbelaere, C.; Wagner, P.; Van Bael, M.K.; Van Tendeloo, G. |
Title |
Analytical TEM study of CVD diamond growth on TiO2 sol-gel layers |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Diamond and related materials |
Abbreviated Journal |
Diam Relat Mater |
Volume |
23 |
Issue |
|
Pages |
93-99 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
The early growth stages of chemical vapor deposition (CVD) diamond on a solgel TiO2 film with buried ultra dispersed diamond seeds (UDD) have been studied. In order to investigate the diamond growth mechanism and understand the role of the TiO2 layer in the growth process, high resolution transmission electron microscopy (HRTEM), energy-filtered TEM and electron energy loss spectroscopy (EELS) techniques were applied to cross sectional diamond film samples. We find evidence for the formation of TiC crystallites inside the TiO2 layer at different diamond growth stages. However, there is no evidence that diamond nucleation starts from these crystallites. Carbon diffusion into the TiO2 layer and the chemical bonding state of carbon (sp2/sp3) were both extensively investigated. We provide evidence that carbon diffuses through the TiO2 layer and that the diamond seeds partially convert to amorphous carbon during growth. This carbon diffusion and diamond to amorphous carbon conversion make the seed areas below the TiO2 layer grow and bend the TiO2 layer upwards to form the nucleation center of the diamond film. In some of the protuberances a core of diamond seed remains, covered by amorphous carbon. It is however unlikely that the remaining seeds are still active during the growth process. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Amsterdam |
Editor |
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Language |
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Wos |
000302887600017 |
Publication Date |
2012-01-26 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
|
Edition |
|
ISSN |
0925-9635; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.561 |
Times cited |
16 |
Open Access |
|
Notes |
Iap; Esteem 026019; Fwo |
Approved |
Most recent IF: 2.561; 2012 IF: 1.709 |
Call Number |
UA @ lucian @ c:irua:95037UA @ admin @ c:irua:95037 |
Serial |
111 |
Permanent link to this record |
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|
Author |
Biermans, E. |
Title |
Electron tomography : from qualitative to quantitative |
Type |
Doctoral thesis |
Year |
2012 |
Publication |
|
Abbreviated Journal |
|
Volume |
|
Issue |
|
Pages |
|
Keywords |
Doctoral thesis; Electron microscopy for materials research (EMAT) |
Abstract |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Antwerpen |
Editor |
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Language |
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Wos |
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Publication Date |
0000-00-00 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
|
ISBN |
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Additional Links |
UA library record |
Impact Factor |
|
Times cited |
|
Open Access |
|
Notes |
|
Approved |
Most recent IF: NA |
Call Number |
UA @ lucian @ c:irua:94220 |
Serial |
989 |
Permanent link to this record |
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|
Author |
Colla, M.-S.; Wang, B.; Idrissi, H.; Schryvers, D.; Raskin, J.-P.; Pardoen, T. |
Title |
High strength-ductility of thin nanocrystalline palladium films with nanoscale twins : on-chip testing and grain aggregate model |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Acta materialia |
Abbreviated Journal |
Acta Mater |
Volume |
60 |
Issue |
4 |
Pages |
1795-1806 |
Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
Abstract |
The mechanical behaviour of thin nanocrystalline palladium films with an ∼30 nm in plane grain size has been characterized on chip under uniaxial tension. The films exhibit a large strain hardening capacity and a significant increase in the strength with decreasing thickness. Transmission electron microscopy has revealed the presence of a moderate density of growth nanotwins interacting with dislocations. A semi-analytical grain aggregate model is proposed to investigate the impact of different contributions to the flow behaviour, involving the effect of twins, of grain size and of the presence of a thin surface layer. This model provides guidelines to optimizing the strength/ductility ratio of the films. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Oxford |
Editor |
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Language |
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Wos |
000301989500035 |
Publication Date |
2012-02-02 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
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Edition |
|
ISSN |
1359-6454; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
5.301 |
Times cited |
38 |
Open Access |
|
Notes |
Iap |
Approved |
Most recent IF: 5.301; 2012 IF: 3.941 |
Call Number |
UA @ lucian @ c:irua:94213 |
Serial |
1465 |
Permanent link to this record |
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Author |
Casavola, M.; van Huis, M.A.; Bals, S.; Lambert, K.; Hens, Z.; Vanmaekelbergh, D. |
Title |
Anisotropic cation exchange in PbSe/CdSe core/shell nanocrystals of different geometry |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Chemistry of materials |
Abbreviated Journal |
Chem Mater |
Volume |
24 |
Issue |
2 |
Pages |
294-302 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
We present a study of Cd2+-for-Pb2+ exchange in PbSe nanocrystals (NCs) with cube, star, and rod shapes. Prolonged temperature-activated cation exchange results in PbSe/CdSe heterostructured nanocrystals (HNCs) that preserve their specific overall shape, whereas the PbSe core is strongly faceted with dominance of {111} facets. Hence, cation exchange proceeds while the Se anion lattice is preserved, and well-defined {111}/{111} PbSe/CdSe interfaces develop. Interestingly, by quenching the reaction at different stages of the cation exchange new structures have been isolated, such as coreshell nanorods, CdSe rods that contain one or two separated PbSe dots and fully zinc blende CdSe nanorods. The crystallographically anisotropic cation exchange has been characterized by a combined HRTEM/HAADF-STEM study of heterointerface evolution over reaction time and temperature. Strikingly, Pb and Cd are only intermixed at the PbSe/CdSe interface. We propose a plausible model for the cation exchange based on a layer-by-layer replacement of Pb2+ by Cd2+ enabled by a vacancy-assisted cation migration mechanism. |
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 |
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Language |
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Wos |
000299367500008 |
Publication Date |
2011-11-17 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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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 |
136 |
Open Access |
|
Notes |
Esteem 026019 |
Approved |
Most recent IF: 9.466; 2012 IF: 8.238 |
Call Number |
UA @ lucian @ c:irua:94211 |
Serial |
124 |
Permanent link to this record |
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Author |
Gao, J.; Lebedev, O.I.; Turner, S.; Li, Y.F.; Lu, Y.H.; Feng, Y.P.; Boullay, P.; Prellier, W.; Van Tendeloo, G.; Wu, T. |
Title |
Phase selection enabled formation of abrupt axial heterojunctions in branched oxide nanowires |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Nano letters |
Abbreviated Journal |
Nano Lett |
Volume |
12 |
Issue |
1 |
Pages |
275-280 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
Rational synthesis of nanowires via the vaporliquidsolid (VLS) mechanism with compositional and structural controls is vitally important for fabricating functional nanodevices from bottom up. Here, we show that branched indium tin oxide nanowires can be in situ seeded in vapor transport growth using tailored AuCu alloys as catalyst. Furthermore, we demonstrate that VLS synthesis gives unprecedented freedom to navigate the ternary InSnO phase diagram, and a rare and bulk-unstable cubic phase can be selectively stabilized in nanowires. The stabilized cubic fluorite phase possesses an unusual almost equimolar concentration of In and Sn, forming a defect-free epitaxial interface with the conventional bixbyite phase of tin-doped indium oxide that is the most employed transparent conducting oxide. This rational methodology of selecting phases and making abrupt axial heterojunctions in nanowires presents advantages over the conventional synthesis routes, promising novel composition-modulated nanomaterials. |
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 |
Editor |
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Language |
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Wos |
000298943100048 |
Publication Date |
2011-12-05 |
Series Editor |
|
Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
1530-6984;1530-6992; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
12.712 |
Times cited |
25 |
Open Access |
|
Notes |
Fwo |
Approved |
Most recent IF: 12.712; 2012 IF: 13.025 |
Call Number |
UA @ lucian @ c:irua:94209 |
Serial |
2587 |
Permanent link to this record |
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Author |
Wang, H.; Cuppens, J.; Biermans, E.; Bals, S.; Fernandez-Ballester, L.; Kvashnina, K.O.; Bras, W.; van Bael, M.J.; Temst, K.; Vantomme, A. |
Title |
Tuning of the size and the lattice parameter of ion-beam synthesized Pb nanoparticles embedded in Si |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Journal of physics: D: applied physics |
Abbreviated Journal |
J Phys D Appl Phys |
Volume |
45 |
Issue |
3 |
Pages |
035301-035301,7 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
The size and lattice constant evolution of Pb nanoparticles (NPs) synthesized by high fluence implantation in crystalline Si have been studied with a variety of experimental techniques. Results obtained from small-angle x-ray scattering showed that the Pb NPs grow with increasing implantation fluence and annealing duration. The theory of NP growth kinetics can be applied to qualitatively explain the size evolution of the Pb NPs during the implantation and annealing processes. Moreover, the lattice constant of the Pb NPs was evaluated by conventional x-ray diffraction. The lattice dilatation was observed to decrease with increasing size of the Pb NPs. Such lattice constant tuning can be attributed to the pseudomorphism caused by the lattice mismatch between the Pb NPs and the Si matrix. |
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 |
|
Language |
|
Wos |
000299308400008 |
Publication Date |
2011-12-23 |
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 |
5 |
Open Access |
|
Notes |
Fwo; Iap |
Approved |
Most recent IF: 2.588; 2012 IF: 2.528 |
Call Number |
UA @ lucian @ c:irua:94208 |
Serial |
3754 |
Permanent link to this record |
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|
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Author |
Guttmann, P.; Bittencourt, C.; Rehbein, S.; Umek, P.; Ke, X.; Van Tendeloo, G.; Ewels, C.P.; Schneider, G. |
Title |
Nanoscale spectroscopy with polarized X-rays by NEXAFS-TXM |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Nature photonics |
Abbreviated Journal |
Nat Photonics |
Volume |
6 |
Issue |
1 |
Pages |
25-29 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
Near-edge X-ray absorption spectroscopy (NEXAFS)1 is an essential analytical tool in material science. Combining NEXAFS with scanning transmission X-ray microscopy (STXM) adds spatial resolution and the possibility to study individual nanostructures2, 3. Here, we describe a full-field transmission X-ray microscope (TXM) that generates high-resolution, large-area NEXAFS data with a collection rate two orders of magnitude faster than is possible with STXM. The TXM optical design combines a spectral resolution of E/ΔE = 1 × 104 with a spatial resolution of 25 nm in a field of view of 1520 µm and a data acquisition time of ~1 s. As an example, we present image stacks and polarization-dependent NEXAFS spectra from individual anisotropic sodium and protonated titanate nanoribbons. Our NEXAFS-TXM technique has the advantage that one image stack visualizes a large number of nanostructures and therefore already contains statistical information. This new high-resolution NEXAFS-TXM technique opens the way to advanced nanoscale science studies. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000298416200011 |
Publication Date |
2011-11-25 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
1749-4885;1749-4893; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
37.852 |
Times cited |
76 |
Open Access |
|
Notes |
|
Approved |
Most recent IF: 37.852; 2012 IF: 27.254 |
Call Number |
UA @ lucian @ c:irua:94198 |
Serial |
2272 |
Permanent link to this record |
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Author |
Schryvers, D.; Van Aert, S. |
Title |
High-resolution visualization techniques : structural aspects |
Type |
H1 Book chapter |
Year |
2012 |
Publication |
|
Abbreviated Journal |
|
Volume |
|
Issue |
|
Pages |
135-149 |
Keywords |
H1 Book chapter; Electron microscopy for materials research (EMAT) |
Abstract |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
Springer |
Place of Publication |
Berlin |
Editor |
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Language |
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Wos |
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Publication Date |
0000-00-00 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
|
ISBN |
978-3-642-20942-0 |
Additional Links |
UA library record |
Impact Factor |
|
Times cited |
|
Open Access |
|
Notes |
|
Approved |
Most recent IF: NA |
Call Number |
UA @ lucian @ c:irua:94124 |
Serial |
1464 |
Permanent link to this record |
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Author |
Wang, A.; Van Aert, S.; Goos, P.; van Dyck, D. |
Title |
Precision of three-dimensional atomic scale measurements from HRTEM images : what are the limits? |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Ultramicroscopy |
Abbreviated Journal |
Ultramicroscopy |
Volume |
114 |
Issue |
|
Pages |
20-30 |
Keywords |
A1 Journal article; Engineering Management (ENM); Electron microscopy for materials research (EMAT); Vision lab |
Abstract |
In this paper, we investigate to what extent high resolution transmission electron microscopy images can be used to measure the mass, in terms of thickness, and surface profile, corresponding to the defocus offset, of an object at the atomic scale. Therefore, we derive an expression for the statistical precision with which these object parameters can be estimated in a quantitative analysis. Evaluating this expression as a function of the microscope settings allows us to derive the optimal microscope design. Acquiring three-dimensional structure information in terms of thickness turns out to be much more difficult than obtaining two-dimensional information on the projected atom column positions. The attainable precision is found to be more strongly affected by processes influencing the image contrast, such as phonon scattering, than by the specific choice of microscope settings. For a realistic incident electron dose, it is expected that atom columns can be distinguished with single atom sensitivity up to a thickness of the order of the extinction distance. A comparable thickness limit is determined to measure surface steps of one atom. An increase of the electron dose shifts the limiting thickness upward due to an increase in the signal-to-noise ratio. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Amsterdam |
Editor |
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Language |
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Wos |
000301954300003 |
Publication Date |
2012-01-06 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0304-3991; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.843 |
Times cited |
5 |
Open Access |
|
Notes |
Fwo |
Approved |
Most recent IF: 2.843; 2012 IF: 2.470 |
Call Number |
UA @ lucian @ c:irua:94116 |
Serial |
2692 |
Permanent link to this record |
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Author |
Van Aert, S.; van den Broek, W.; Goos, P.; van Dyck, D. |
Title |
Model-based electron microscopy : from images toward precise numbers for unknown structure parameters |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Micron |
Abbreviated Journal |
Micron |
Volume |
43 |
Issue |
4 |
Pages |
509-515 |
Keywords |
A1 Journal article; Engineering Management (ENM); Electron microscopy for materials research (EMAT); Vision lab |
Abstract |
Statistical parameter estimation theory is proposed as a method to quantify electron microscopy images. It aims at obtaining precise and accurate values for the unknown structure parameters including, for example, atomic column positions and types. In this theory, observations are purely considered as data planes, from which structure parameters have to be determined using a parametric model describing the images. The method enables us to measure positions of atomic columns with a precision of the order of a few picometers even though the resolution of the electron microscope is one or two orders of magnitude larger. Moreover, small differences in averaged atomic number, which cannot be distinguished visually, can be quantified using high-angle annular dark field scanning transmission electron microscopy images. Finally, it is shown how to optimize the experimental design so as to attain the highest precision. As an example, the optimization of the probe size for nanoparticle radius measurements is considered. It is also shown how to quantitatively balance signal-to-noise ratio and resolution by adjusting the probe size. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Oxford |
Editor |
|
Language |
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Wos |
000301702400003 |
Publication Date |
2011-11-03 |
Series Editor |
|
Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0968-4328; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
1.98 |
Times cited |
7 |
Open Access |
|
Notes |
Fwo |
Approved |
Most recent IF: 1.98; 2012 IF: 1.876 |
Call Number |
UA @ lucian @ c:irua:94114 |
Serial |
2099 |
Permanent link to this record |
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Author |
Van Aert, S.; Turner, S.; Delville, R.; Schryvers, D.; Van Tendeloo, G.; Salje, E.K.H. |
Title |
Direct observation of ferrielectricity at ferroelastic domain boundaries in CaTiO3 by electron microscopy |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Advanced materials |
Abbreviated Journal |
Adv Mater |
Volume |
24 |
Issue |
4 |
Pages |
523-527 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
High-resolution aberration-corrected transmission electron microscopy aided by statistical parameter estimation theory is used to quantify localized displacements at a (110) twin boundary in orthorhombic CaTiO3. The displacements are 36 pm for the Ti atoms and confined to a thin layer. This is the first direct observation of the generation of ferroelectricity by interfaces inside this material which opens the door for domain boundary engineering. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
|
Place of Publication |
Weinheim |
Editor |
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Language |
|
Wos |
000299156400011 |
Publication Date |
2011-12-24 |
Series Editor |
|
Series Title |
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Abbreviated Series Title |
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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 |
150 |
Open Access |
|
Notes |
Fwo |
Approved |
Most recent IF: 19.791; 2012 IF: 14.829 |
Call Number |
UA @ lucian @ c:irua:94110 |
Serial |
717 |
Permanent link to this record |
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Author |
Sels, D.; Brosens, F.; Magnus, W. |
Title |
On the path integral representation of the Wigner function and the BarkerMurray ansatz |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physics letters : A |
Abbreviated Journal |
Phys Lett A |
Volume |
376 |
Issue |
6/7 |
Pages |
809-812 |
Keywords |
A1 Journal article; Theory of quantum systems and complex systems; Condensed Matter Theory (CMT) |
Abstract |
The propagator of the Wigner function is constructed from the WignerLiouville equation as a phase space path integral over a new effective Lagrangian. In contrast to a paper by Barker and Murray (1983) [1], we show that the path integral can in general not be written as a linear superposition of classical phase space trajectories over a family of non-local forces. Instead, we adopt a saddle point expansion to show that the semiclassical Wigner function is a linear superposition of classical solutions for a different set of non-local time dependent forces. As shown by a simple example the specific form of the path integral makes the formulation ideal for Monte Carlo simulation. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Amsterdam |
Editor |
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Language |
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Wos |
000301167300005 |
Publication Date |
2012-01-17 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0375-9601; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
1.772 |
Times cited |
7 |
Open Access |
|
Notes |
; ; |
Approved |
Most recent IF: 1.772; 2012 IF: 1.766 |
Call Number |
UA @ lucian @ c:irua:94006 |
Serial |
2445 |
Permanent link to this record |
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Author |
Goris, B.; van den Broek, W.; Batenburg, K.J.; Heidari Mezerji, H.; Bals, S. |
Title |
Electron tomography based on a total variation minimization reconstruction technique |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Ultramicroscopy |
Abbreviated Journal |
Ultramicroscopy |
Volume |
113 |
Issue |
|
Pages |
120-130 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab |
Abstract |
The 3D reconstruction of a tilt series for electron tomography is mostly carried out using the weighted backprojection (WBP) algorithm or using one of the iterative algorithms such as the simultaneous iterative reconstruction technique (SIRT). However, it is known that these reconstruction algorithms cannot compensate for the missing wedge. Here, we apply a new reconstruction algorithm for electron tomography, which is based on compressive sensing. This is a field in image processing specialized in finding a sparse solution or a solution with a sparse gradient to a set of ill-posed linear equations. Therefore, it can be applied to electron tomography where the reconstructed objects often have a sparse gradient at the nanoscale. Using a combination of different simulated and experimental datasets, it is shown that missing wedge artefacts are reduced in the final reconstruction. Moreover, it seems that the reconstructed datasets have a higher fidelity and are easier to segment in comparison to reconstructions obtained by more conventional iterative algorithms. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Amsterdam |
Editor |
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Language |
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Wos |
000300554400006 |
Publication Date |
2011-11-14 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
0304-3991; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.843 |
Times cited |
171 |
Open Access |
|
Notes |
Fwo |
Approved |
Most recent IF: 2.843; 2012 IF: 2.470 |
Call Number |
UA @ lucian @ c:irua:93637 |
Serial |
987 |
Permanent link to this record |
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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 |
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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 |
000298409000011 |
Publication Date |
2011-12-14 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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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 |
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Author |
Xu, Q.; Zandbergen, H.W.; van Dyck, D. |
Title |
Imaging from atomic structure to electronic structure |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Micron |
Abbreviated Journal |
Micron |
Volume |
43 |
Issue |
4 |
Pages |
524-531 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab |
Abstract |
This paper discusses the possibility of retrieving the electron distribution (with highlighted valence electron distribution information) of materials from recorded HREM images. This process can be achieved by solving two inverse problems: reconstruction of the exit wave and reconstruction of the electron distribution from exit waves. The first inverse problem can be solved using a focal series reconstruction method. We show that the second inverse problem can be solved by combining a series of exit waves recorded at different thickness conditions. This process is designed based on an improved understanding of the dynamical scattering process. It also explains the fundamental difficulty of obtaining the valence electron distribution information and the basis of our solution. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Oxford |
Editor |
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Language |
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Wos |
000301702400005 |
Publication Date |
2011-11-05 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
0968-4328; |
ISBN |
|
Additional Links |
UA library record; WoS full record |
Impact Factor |
1.98 |
Times cited |
|
Open Access |
|
Notes |
Fwo |
Approved |
Most recent IF: 1.98; 2012 IF: 1.876 |
Call Number |
UA @ lucian @ c:irua:93634 |
Serial |
1553 |
Permanent link to this record |
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Author |
Kuznetsov, A.S.; Cuong, N.T.; Tikhomirov, V.K.; Jivanescu, M.; Stesmans, A.; Chibotaru, L.F.; Velázquez, J.J.; Rodríguez, V.D.; Kirilenko, D.; Van Tendeloo, G.; Moshchalkov, V.V. |
Title |
Effect of heat-treatment on luminescence and structure of Ag nanoclusters doped oxyfluoride glasses and implication for fiber drawing |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Optical materials |
Abbreviated Journal |
Opt Mater |
Volume |
34 |
Issue |
4 |
Pages |
616-621 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
The effect of heat treatment on the structure and luminescence of Ag nanoclusters doped oxyfluoride glasses was studied and the implication for drawing the corresponding fibers doped with luminescent Ag nanoclusters has been proposed. The heat treatment results, first, in condensation of the Ag nanoclusters into larger Ag nanoparticles and loss of Ag luminescence, and further heat treatment results in precipitation of a luminescent-loss nano- and microcrystalline Ag phases onto the surface of the glass. Thus, the oxyfluoride fiber doped with luminescent Ag nanoclusters was pulled from the viscous glass melt and its attenuation loss was 0.19 dB/cm in the red part of the spectrum; i.e. near to the maximum of Ag nanoclusters luminescence band. The nucleation centers for the Ag nanoclusters in oxyfluoride glasses have been suggested to be the fluorine vacancies and their nanoclusters. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Amsterdam |
Editor |
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Language |
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Wos |
000300124500006 |
Publication Date |
2011-10-18 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
0925-3467; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.238 |
Times cited |
25 |
Open Access |
|
Notes |
Methusalem |
Approved |
Most recent IF: 2.238; 2012 IF: 1.918 |
Call Number |
UA @ lucian @ c:irua:93632 |
Serial |
811 |
Permanent link to this record |
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Author |
Corthals, S.; van Noyen, J.; Geboers, J.; Vosch, T.; Liang, D.; Ke, X.; Hofkens, J.; Van Tendeloo, G.; Jacobs, P.; Sels, B. |
Title |
The beneficial effect of CO2 in the low temperature synthesis of high quality carbon nanofibers and thin multiwalled carbon nanotubes from CH_{4} over Ni catalysts |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Carbon |
Abbreviated Journal |
Carbon |
Volume |
50 |
Issue |
2 |
Pages |
372-384 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
A low temperature chemical vapor deposition method is described for converting CH4 into high-quality carbon nanofibers (CNFs) using a Ni catalyst supported on either spinel or perovskite oxides in the presence of CO2. The addition of CO2 has a significant influence on CNF purity and stability, while the CNF diameter distribution is significantly narrowed. Ultimately, the addition of CO2 changes the CNF structure from fishbone fibers to thin multiwalled carbon nanotubes. A new in situ cooling principle taking into account dry reforming chemistry and thermodynamics is introduced to account for the structural effects of CO2. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Oxford |
Editor |
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Language |
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Wos |
000297397700004 |
Publication Date |
2011-09-01 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
0008-6223; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
6.337 |
Times cited |
26 |
Open Access |
|
Notes |
Iwt; Iap |
Approved |
Most recent IF: 6.337; 2012 IF: 5.868 |
Call Number |
UA @ lucian @ c:irua:93626 |
Serial |
228 |
Permanent link to this record |
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Author |
Verbeeck, J.; Tian, H.; Béché, A. |
Title |
A new way of producing electron vortex probes for STEM |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Ultramicroscopy |
Abbreviated Journal |
Ultramicroscopy |
Volume |
113 |
Issue |
|
Pages |
83-87 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
A spiral holographic aperture is used in the condensor plane of a scanning transmission electron microscope to produce a focussed electron vortex probe carrying a topological charge of either −1, 0 or +1. The spiral aperture design has a major advantage over the previously used forked aperture in that the three beams with topological charge m=−1, 0, and 1 are not side by side in the specimen plane, but rather on top of each other, focussed at different heights. This allows us to have only one selected beam in focus on the sample while the others contribute only to a background signal. In this paper we describe the working principle as well as first experimental results demonstrating atomic resolution HAADF STEM images obtained with electron vortex probes. These results pave the way for atomic resolution magnetic information when combined with electron energy loss spectroscopy. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
|
Place of Publication |
Amsterdam |
Editor |
|
Language |
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Wos |
000300554400002 |
Publication Date |
2011-10-31 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
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Edition |
|
ISSN |
0304-3991; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.843 |
Times cited |
62 |
Open Access |
|
Notes |
J.V. wants to thank Miles Padgett for suggesting this setup and pointing to the relevant optics literature. Peter Schattschneider is acknowledged for in depth discussions on related topics. J.V acknowledges funding from the European Research Council under the 7th Framework Program (FP7), ERC Grant no. 46791-COUN-TATOMS and ERC Starting Grant no. 278510 VORTEX. The Qu-Ant-EM microscope is partially funded by the Hercules fund of the Flemish Government. ECASJO_; |
Approved |
Most recent IF: 2.843; 2012 IF: 2.470 |
Call Number |
UA @ lucian @ c:irua:93624UA @ admin @ c:irua:93624 |
Serial |
2336 |
Permanent link to this record |
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Author |
Fang, C.M.; van Huis, M.A.; Zandbergen, H.W. |
Title |
Stability and structures of the CFCC-TmC phases : a first-principles study |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Computational materials science |
Abbreviated Journal |
Comp Mater Sci |
Volume |
51 |
Issue |
1 |
Pages |
146-150 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
The η-M6C, γ-M23C6, and π-M11C2 phases (M = Cr, Mn and Fe) have complex cubic lattices with lattice parameters of approximately 1.0 nm. They belong to the CFCC-TmC family (complex face-centered cubic transition metal carbides), display a rich variety of crystal structures, and play in important role in iron alloys and steels. Here we show that first-principles calculations predict high stability for the γ-M23C6 and η-M6C phases, and instability for the π-M11C2 phases, taking into account various compositional and structural possibilities. The calculations also show a wide variety in magnetic properties. The Cr-containing phases were found to be non-magnetic and the Fe-phases to be ferromagnetic, while the Mn-containing phases were found to be either ferrimagnetic or non-magnetic. Details of the local atomic structures, and the formation and stability of these precipitates in alloys are discussed. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
|
Place of Publication |
|
Editor |
|
Language |
|
Wos |
000296214300020 |
Publication Date |
2011-08-29 |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0927-0256; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.292 |
Times cited |
18 |
Open Access |
|
Notes |
|
Approved |
Most recent IF: 2.292; 2012 IF: 1.878 |
Call Number |
UA @ lucian @ c:irua:93277 |
Serial |
3119 |
Permanent link to this record |
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Author |
Zhang, Y.-R.; Xu, X.; Bogaerts, A.; Wang, Y.-N. |
Title |
Fluid simulation of the phase-shift effect in hydrogen capacitively coupled plasmas: 2 : radial uniformity of the plasma characteristics |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Journal of physics: D: applied physics |
Abbreviated Journal |
J Phys D Appl Phys |
Volume |
45 |
Issue |
1 |
Pages |
015203-015203,13 |
Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
Abstract |
A two-dimensional fluid model, including the full set of Maxwell equations, has been developed and applied to investigate the effect of a phase shift between two power sources on the radial uniformity of several plasma characteristics in a hydrogen capacitively coupled plasma. This study was carried out at various frequencies in the range 13.56200 MHz. When the frequency is low, at 13.56 MHz, the plasma density is characterized by an off-axis peak when both power sources are in-phase (phgr = 0), and the best radial uniformity is obtained at phgr = π. This trend can be explained because the radial nonuniformity caused by the electrostatic edge effect can be effectively suppressed by the phase-shift effect at a phase difference equal to π. When the frequency rises to 60 MHz, the plasma density profiles shift smoothly from edge-peaked over uniform to centre-peaked as the phase difference increases, due to the pronounced standing-wave effect, and the best radial uniformity is reached at phgr = 0.3π. At a frequency of 100 MHz, a similar behaviour is observed, except that the maximum of the plasma density moves again towards the radial edge at the reverse-phase case (phgr = π), because of the dominant skin effect. When the frequency is 200 MHz, the bulk plasma density increases significantly with increasing phase-shift values, and a better uniformity is obtained at phgr = 0.4π. This is because the density in the centre increases faster than at the radial edge as the phase difference rises, due to the increasing power deposition Pz in the centre and the decreasing power density Pr at the radial edge. As the phase difference increases to π, the maximum near the radial edge becomes obvious again. This is because the skin effect has a predominant influence on the plasma density under this condition, resulting in a high density at the radial edge. Moreover, the axial ion flux increases monotonically with phase difference, and exhibits similar profiles to the plasma density. The calculation results illustrate that the radial uniformity of the various plasma characteristics is strongly dependent on the applied frequency and the phase shift between both power sources, which is important to realize, for controlling the uniformity of the plasma etch and deposition processes. |
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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 |
000298290000012 |
Publication Date |
2011-12-12 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0022-3727;1361-6463; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.588 |
Times cited |
15 |
Open Access |
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Notes |
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Approved |
Most recent IF: 2.588; 2012 IF: 2.528 |
Call Number |
UA @ lucian @ c:irua:92852 |
Serial |
1231 |
Permanent link to this record |
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Author |
Zhang, Y.-R.; Xu, X.; Bogaerts, A.; Wang, Y.-N. |
Title |
Fluid simulation of the phase-shift effect in hydrogen capacitively coupled plasmas: 1 : transient behaviour of electrodynamics and power deposition |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Journal of physics: D: applied physics |
Abbreviated Journal |
J Phys D Appl Phys |
Volume |
45 |
Issue |
1 |
Pages |
015202-015202,11 |
Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
Abstract |
A two-dimensional self-consistent fluid model coupled with the full set of Maxwell equations is established to investigate the phase-shift effect on the transient behaviour of electrodynamics and power deposition in a hydrogen capacitively coupled plasma. The effect has been examined at 13.56 MHz and 100 MHz, respectively, because of the different phase-shift modulation when the electromagnetic effects are dominant. The results indicate that the spatiotemporal distributions of the plasma characteristics obtained for various phase-shift cases are obviously different both in shape and especially in absolute values. Indeed, when the phase difference varies from 0 to π, there is an increase in the electron flux, thus the power deposition becomes more pronounced. At the frequency of 13.56 MHz, the axial electron flux in the bulk plasma becomes uniform along the z-axis, and the radial electron flux exhibits two peaks within one period at the reverse-phase case, whereas the oscillation is less pronounced at the in-phase case. Furthermore, in the very high frequency discharge, the radial electron flux is alternately positive and negative with four peaks during one period, and the ionization mainly occurs in the sheath region, due to the prominent power deposition there at a phase difference equal to π. |
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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 |
000298290000011 |
Publication Date |
2011-12-12 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0022-3727;1361-6463; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.588 |
Times cited |
57 |
Open Access |
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Notes |
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Approved |
Most recent IF: 2.588; 2012 IF: 2.528 |
Call Number |
UA @ lucian @ c:irua:92851 |
Serial |
1230 |
Permanent link to this record |
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Author |
Sels, D.; Brosens, F.; Magnus, W. |
Title |
Classical trajectories : a powerful tool for solving tunneling problems |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physica: A : theoretical and statistical physics |
Abbreviated Journal |
Physica A |
Volume |
391 |
Issue |
1/2 |
Pages |
78-81 |
Keywords |
A1 Journal article; Theory of quantum systems and complex systems; Condensed Matter Theory (CMT) |
Abstract |
In the realm of Ehrenfests theorem, classical trajectories obeying Newtons laws have been proven useful to construct explicit solutions to the time-dependent WignerLiouville equation. Whereas previous works have particularly focused on the initial distribution function as a vehicle found to carry the signatures of quantum statistics into the time-dependent solution, the present paper shows that the LagrangeCharpit method based on classical trajectories can be successfully invoked as well to tackle quantum mechanical features with no classical counterpart, such as tunneling. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Amsterdam |
Editor |
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Language |
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Wos |
000297230700010 |
Publication Date |
2011-08-25 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0378-4371; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.243 |
Times cited |
7 |
Open Access |
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Notes |
; ; |
Approved |
Most recent IF: 2.243; 2012 IF: 1.676 |
Call Number |
UA @ lucian @ c:irua:92359 |
Serial |
370 |
Permanent link to this record |
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Author |
Vernimmen, J.; Meynen, V.; Mertens, M.; Lebedev, O.I.; Van Tendeloo, G.; Cool, P. |
Title |
Formation of a Ti-siliceous trimodal material with macroholes, mesopores and zeolitic features via a one-pot templating synthesis |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Journal of porous materials |
Abbreviated Journal |
J Porous Mat |
Volume |
19 |
Issue |
2 |
Pages |
153-160 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA) |
Abstract |
Based on a facile one-pot templating synthesis, using a TS-1 zeolite recipe whereby part of the zeolite structure directing agent is replaced by a mesopore templating agent, a trimodal material is formed. The resulting meso-TSM material combines mesoporosity (Ti-MCM-41) with zeolitic features (TS-1) and a unique sheet-like morphology with uniform macroporous voids (macroholes). Moreover, the macrohole formation, mesoporosity and zeolitic properties of the meso-TSM material can be controlled in a straightforward way by adjusting the length of the hydrothermal treatment. This newly developed material may imply great potential for catalytic redox applications and diffusion limitated processes because of its highly tunable character in all three dimensions (micro-, meso- and macroporous scale). |
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Corporate Author |
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Thesis |
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Publisher |
Kluwer Academic |
Place of Publication |
Boston, Mass. |
Editor |
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Language |
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Wos |
000301187600002 |
Publication Date |
2011-03-28 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1380-2224;1573-4854; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
1.624 |
Times cited |
2 |
Open Access |
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Notes |
Fwo; Goa |
Approved |
Most recent IF: 1.624; 2012 IF: 1.348 |
Call Number |
UA @ lucian @ c:irua:88367 |
Serial |
1257 |
Permanent link to this record |
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Author |
Cooper, D.; Denneulin, T.; Barnes, J.-P.; Hartmann, J.-M.; Hutin, L.; Le Royer, C.; Béché, A.; Rouvière, J.-L. |
Title |
Strain mapping with nm-scale resolution for the silicon-on-insulator generation of semiconductor devices by advanced electron microscopy |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Applied Physics Letters |
Abbreviated Journal |
Appl Phys Lett |
Volume |
112 |
Issue |
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Pages |
124505 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
Strain engineering in the conduction channel is a cost effective method of boosting the performance in state-of-the-art semiconductor devices. However, given the small dimensions of these devices, it is difficult to quantitatively measure the strain with the required spatial resolution. Three different transmission electron microscopy techniques, high-angle annular dark field scanning transmission electron microscopy, dark field electron holography, and nanobeam electron diffraction have been applied to measure the strain in simple bulk and SOI calibration specimens. These techniques are then applied to different gate length SiGe SOI pFET devices in order to measure the strain in the conduction channel. For these devices, improved spatial resolution is required, and strain maps with spatial resolutions as good as 1 nm have been achieved. Finally, we discuss the relative advantages and disadvantages of using these three different techniques when used for strain measurement. |
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Corporate Author |
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Thesis |
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Publisher |
American Institute of Physics |
Place of Publication |
New York, N.Y. |
Editor |
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Language |
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Wos |
000312829400128 |
Publication Date |
2012-12-19 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0003-6951; 1077-3118 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.411 |
Times cited |
14 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.411; 2012 IF: 3.794 |
Call Number |
UA @ lucian @ c:irua:136433 |
Serial |
4510 |
Permanent link to this record |