| |
Records |
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Author |
Gagea, B.C.; Liang, D.; Van Tendeloo, G.; Martens, J.A.; Jacobs, P.A. |
| |
Title |
Synthesis and characterization of nanocrystal zeolite/mesoporous matrix composite material |
Type |
P1 Proceeding |
| |
Year |
2006 |
Publication |
Studies in surface science and catalysis |
Abbreviated Journal |
|
| |
Volume |
162 |
Issue |
|
Pages |
259-266 |
| |
Keywords |
P1 Proceeding; Electron microscopy for materials research (EMAT) |
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Abstract |
|
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Address |
|
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Corporate Author |
|
Thesis |
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Publisher |
|
Place of Publication |
Amsterdam |
Editor |
|
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Language |
|
Wos |
000283580900033 |
Publication Date |
2007-09-07 |
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Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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| |
Series Volume |
|
Series Issue |
|
Edition |
|
| |
ISSN |
0167-2991; |
ISBN |
|
Additional Links  |
UA library record; WoS full record; WoS citing articles |
| |
Impact Factor |
|
Times cited |
8 |
Open Access |
|
| |
Notes |
|
Approved |
Most recent IF: NA |
| |
Call Number |
UA @ lucian @ c:irua:99275 |
Serial |
3413 |
| Permanent link to this record |
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|
| |
|
Author |
Razavi, F.S.; Gross, G.; Habermeier, H.-U.; Lebedev, O.; Amelinckx, S.; Van Tendeloo, G.; Vigliante, A. |
| |
Title |
Epitaxial strain induced metal insulator transition in La0.9Sr0.1MnO3 and La0.88Sr0.1MnO3 thin films |
Type |
A1 Journal article |
| |
Year |
2000 |
Publication |
Applied physics letters |
Abbreviated Journal |
Appl Phys Lett |
| |
Volume |
76 |
Issue |
2 |
Pages |
155-157 |
| |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| |
Abstract |
We are reporting an unexpected metal insulator transition at the ferromagnetic phase-transition temperature for thin films of La0.9Sr0.1MnO3 (< 50 nm), grown on a (100) face of SrTiO3 substrate. For the thicker films (> 50 nm), similar to the single crystal, no such transition is observed below T-C. Additionally, we observe the suppression of the features associated with charge or orbital ordering in intentionally La-deficient thin films of La0.88Sr0.1MnO3 (< 75 nm). In thin films, transmission electron microscopy reveals a compressive strain due to the epitaxial growth, that is, lattice parameters adopt those of the cubic lattice of SrTiO3. As the film thickness increases, coherent microtwinning is observed in the films and the films relax to a orthorhombic structure. (C) 2000 American Institute of Physics. [S0003-6951(00)00402-2]. |
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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 |
|
| |
Language |
|
Wos |
000084541000009 |
Publication Date |
2002-07-26 |
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Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| |
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 |
91 |
Open Access |
|
| |
Notes |
|
Approved |
Most recent IF: 3.411; 2000 IF: 3.906 |
| |
Call Number |
UA @ lucian @ c:irua:99441 |
Serial |
1073 |
| Permanent link to this record |
| |
|
| |
|
Author |
Laffez, P.; Van Tendeloo, G.; Millange, F.; Caignaert, V.; Hervieu, M.; Raveau, B. |
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Title |
Structural phase transition at low temperature, corresponding to charge ordering in the CMR perovskites LN0.5A0.5MNO3 |
Type |
A1 Journal article |
| |
Year |
1996 |
Publication |
Materials research bulletin |
Abbreviated Journal |
Mater Res Bull |
| |
Volume |
31 |
Issue |
8 |
Pages |
905-911 |
| |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| |
Abstract |
The magneto resistive perovskites Nd0.5Sr0.5MnO3 and Pr0.5Sr0.41Ca0.09MnO3 undergo a transition from anti ferromagnetic insulator to ferromagnetic metal as function of temperature. The room temperature phase is orthorhombic with the space group Imma and the cell parameters a approximate to root 2a(p), b approximate to 2a(p), and c approximate to root 2a(p). A structural phase transition related to charge ordering accompanying the transition from ferromagnetic state to antiferromagnetic state has been evidenced by low temperature electron diffraction. This transition is reversible and a new superstructure, with a P-type orthorhombic cell. and lattice parameters parameters a approximate to 2 root 2a(p), b approximate to 2a(p), and c approximate to root 2a(p), is formed. |
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Address |
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Corporate Author |
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Thesis |
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| |
Publisher |
|
Place of Publication |
New York, N.Y. |
Editor |
|
| |
Language |
|
Wos |
A1996UZ37300002 |
Publication Date |
2002-07-25 |
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
| |
ISSN |
0025-5408; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| |
Impact Factor |
2.288 |
Times cited |
25 |
Open Access |
|
| |
Notes |
|
Approved |
|
| |
Call Number |
UA @ lucian @ c:irua:99650 |
Serial |
3246 |
| Permanent link to this record |
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|
| |
|
Author |
Zhang, X.F.; Van Tendeloo, G.; Amelinckx, S.; Pelloquin, D.; Michel, C.; Hervieu, M.; Raveau, B. |
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Title |
Structural aspects of Bi2-xPbxSr3.5Cu2(CO3)O8-\delta for 0\leq x\leq0.75 : an electron-microscopy study |
Type |
A1 Journal article |
| |
Year |
1994 |
Publication |
Journal of solid state chemistry |
Abbreviated Journal |
J Solid State Chem |
| |
Volume |
113 |
Issue |
2 |
Pages |
327-344 |
| |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| |
Abstract |
The structure and defect structure of Bi2-xPbxSr3.5Cu2 (CO3)O8-delta compounds with 0 less-than-or-equal-to x less-than-or-equal-to 0.75 are carefully investigated by electron diffraction and high-resolution electron microscopy. All compounds have an orthorhombic structure with a almost-equal-to b almost-equal-to 5.4 angstrom and c almost-equal-to 39.5 angstrom. The length of the b-axis decreases monotonically with increasing x. The space group for the basic structure is Abm2. The structure can be considered as an intergrowth of Bi2Sr2CuO6 lamellae with Sr2CuO2 (CO3) lamellae along the c-axis. CO3 groups behave as bridges connecting the CuO6 octahedra. In the x = 0 compound the carbon atoms are shifted away from their symmetry positions; the orientational ordering of the CO3 groups (or the carbon shift) in successive CO planes alternates along +b and -b. Typical Bi-type and Pb-type modulations are found along the b-axis up to a Pb content x = 0.5. Electron beam irradiation destroys the ordering of the CO3 groups and alters the modulated structure. (C) 1994 Academic press, inc. |
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Address |
|
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Corporate Author |
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Thesis |
|
| |
Publisher |
|
Place of Publication |
London |
Editor |
|
| |
Language |
|
Wos |
A1994PX18600016 |
Publication Date |
2002-10-07 |
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
| |
ISSN |
0022-4596; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| |
Impact Factor |
2.133 |
Times cited |
8 |
Open Access |
|
| |
Notes |
|
Approved |
|
| |
Call Number |
UA @ lucian @ c:irua:99810 |
Serial |
3210 |
| Permanent link to this record |
| |
|
| |
|
Author |
Zhang, Z.; Ma, L.N.; Liao, X.Z.; van Landuyt, J. |
| |
Title |
A transmission electron-microscopy study of crystalline surface domains on al-co decagonal quasi-crystals and the \tau2-Al13CO4 approximant |
Type |
A1 Journal article |
| |
Year |
1994 |
Publication |
Philosophical magazine letters |
Abbreviated Journal |
Phil Mag Lett |
| |
Volume |
70 |
Issue |
5 |
Pages |
303-310 |
| |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| |
Abstract |
Twin-domains of a b.c.c. crystalline phase with a = 0.29 nm have been found in a surface layer on surfaces of Al-Co decagonal quasicrystals and the coexisting tau(2)-Al13Co4 crystalline approximant. These surface layer domains are introduced during the preparation of electron microscopy thin films by ion milling. |
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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 |
London |
Editor |
|
| |
Language |
|
Wos |
A1994PQ20900008 |
Publication Date |
2007-07-08 |
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Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
| |
ISSN |
0950-0839;1362-3036; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| |
Impact Factor |
1.087 |
Times cited |
4 |
Open Access |
|
| |
Notes |
|
Approved |
no |
| |
Call Number |
UA @ lucian @ c:irua:99816 |
Serial |
3715 |
| Permanent link to this record |
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| |
|
Author |
Gensterblum, G.; Hevesi, K.; Han, B.Y.; Yu, L.M.; Pireaux, J.J.; Thiry, P.A.; Caudano, R.; Lucas, A.A.; Bernaerts, D.; Amelinckx, S.; Van Tendeloo, G.; Bendele, G.; Buslaps, T.; Johnson, R.L.; Foss, M.; Feidenhans’l, R.; Le Lay, G.; |
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Title |
Growth mode and electronic-structure of the epitaxial C60(111)/GeS(001) interface |
Type |
A1 Journal article |
| |
Year |
1994 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| |
Volume |
50 |
Issue |
16 |
Pages |
11981-11995 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
|
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Address |
|
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Corporate Author |
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Thesis |
|
| |
Publisher |
|
Place of Publication |
Lancaster, Pa |
Editor |
|
| |
Language |
|
Wos |
A1994PR43400080 |
Publication Date |
2002-07-27 |
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Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
| |
ISSN |
0163-1829;1095-3795; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| |
Impact Factor |
3.736 |
Times cited |
81 |
Open Access |
|
| |
Notes |
|
Approved |
no |
| |
Call Number |
UA @ lucian @ c:irua:99825 |
Serial |
1393 |
| Permanent link to this record |
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|
| |
|
Author |
Ivanov, V.; Nagy, J.B.; Lambin, P.; Lucas, A.; Zhang, X.B.; Zhang, X.F.; Bernaerts, D.; Van Tendeloo, G.; Amelinckx, S.; van Landuyt, J. |
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Title |
The study of carbon nanotubules produced by catalytic method |
Type |
A1 Journal article |
| |
Year |
1994 |
Publication |
Chemical physics letters |
Abbreviated Journal |
Chem Phys Lett |
| |
Volume |
223 |
Issue |
4 |
Pages |
329-335 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| |
Abstract |
Catalytic methods for the production of carbon nanotubules have been developed based on the decomposition of acetylene on well-dispersed metal particles strongly adsorbed on a support. Cobalt on silica was found to be the best catalyst-support combination for the production of graphitic tubules. The method for the catalyst preparation and the reaction conditions were optimized. Straight and coiled carbon tubules were obtained with inner and outer diameter of 3-7 and 15-20 nm, respectively, and up to 30 mum in length. These nanotubules were not coated by amorphous carbon. Traces of amorphous carbon could be removed by hydrogen. High resolution electron microscopy images and electron diffraction patterns of the straight nanotubules were similar to those obtained by the arc-discharge method. Coiled nanotubules were revealed by TEM to be regular polygonized helices where the bends are caused by pairs of pentagon-heptagon carbon rings among the hexagonal network. |
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Address |
|
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Corporate Author |
|
Thesis |
|
| |
Publisher |
|
Place of Publication |
Amsterdam |
Editor |
|
| |
Language |
|
Wos |
A1994NT08000011 |
Publication Date |
2002-07-25 |
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Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
| |
ISSN |
0009-2614; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| |
Impact Factor |
1.897 |
Times cited |
405 |
Open Access |
|
| |
Notes |
|
Approved |
PHYSICS, APPLIED 47/145 Q2 # |
| |
Call Number |
UA @ lucian @ c:irua:99869 |
Serial |
3595 |
| Permanent link to this record |
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|
| |
|
Author |
Goessens, C.; Schryvers, D.; van Dyck, D.; van Landuyt, J.; de Keyzer, R. |
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Title |
Electron-diffraction evidence for ordering of interstitial silver ions in silver bromide microcrystals |
Type |
A1 Journal article |
| |
Year |
1994 |
Publication |
Physica status solidi: A |
Abbreviated Journal |
|
| |
Volume |
143 |
Issue |
2 |
Pages |
277-287 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab |
| |
Abstract |
The occurrence and origin of diffuse intensity contours in electron micrographs of AgBr crystals are investigated. The observations are interpreted in terms of a model, which attributes diffuse scattering to the presence of predominant atom or vacancy clusters of a particular polyhedral type. It is shown that irrespective of the crystal morphology, interstitial Ag ions order in AgBr material in clusters of finite size along 001 type planes. A different geometry of the diffuse intensity locus observed for triangular and hexagonal tabular grains is explained in terms of the different twin plane morphology of these grains. |
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Address |
|
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Corporate Author |
|
Thesis |
|
| |
Publisher |
|
Place of Publication |
Berlin |
Editor |
|
| |
Language |
|
Wos |
A1994NW15300010 |
Publication Date |
2007-01-12 |
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Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
| |
ISSN |
0031-8965;1521-396X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| |
Impact Factor |
|
Times cited |
7 |
Open Access |
|
| |
Notes |
|
Approved |
no |
| |
Call Number |
UA @ lucian @ c:irua:99870 |
Serial |
919 |
| Permanent link to this record |
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|
| |
|
Author |
Nistor, L.C.; Van Tendeloo, G.; Amelinckx, S. |
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Title |
Defects and phase transition in monoclinic natural hollandite : BaxMn8O16 |
Type |
A1 Journal article |
| |
Year |
1994 |
Publication |
Journal of solid state chemistry |
Abbreviated Journal |
J Solid State Chem |
| |
Volume |
109 |
Issue |
1 |
Pages |
152-165 |
| |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
|
| |
Address |
|
| |
Corporate Author |
|
Thesis |
|
| |
Publisher |
|
Place of Publication |
London |
Editor |
|
| |
Language |
|
Wos |
A1994MY48800024 |
Publication Date |
2002-10-07 |
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
| |
ISSN |
0022-4596; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| |
Impact Factor |
2.133 |
Times cited |
13 |
Open Access |
|
| |
Notes |
|
Approved |
no |
| |
Call Number |
UA @ lucian @ c:irua:99918 |
Serial |
627 |
| Permanent link to this record |
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|
| |
|
Author |
Milat, O.; Van Tendeloo, G.; Amelinckx, S.; Babu, T.G.N.; Greaves, C. |
| |
Title |
Superstructure and structural variants in Sr2CuO2(CO3) |
Type |
A1 Journal article |
| |
Year |
1994 |
Publication |
Journal of solid state chemistry |
Abbreviated Journal |
J Solid State Chem |
| |
Volume |
109 |
Issue |
1 |
Pages |
5-14 |
| |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| |
Abstract |
|
| |
Address |
|
| |
Corporate Author |
|
Thesis |
|
| |
Publisher |
|
Place of Publication |
London |
Editor |
|
| |
Language |
|
Wos |
A1994MY48800002 |
Publication Date |
2002-09-18 |
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
| |
ISSN |
0022-4596; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| |
Impact Factor |
2.133 |
Times cited |
11 |
Open Access |
|
| |
Notes |
|
Approved |
PHYSICS, APPLIED 28/145 Q1 # |
| |
Call Number |
UA @ lucian @ c:irua:99919 |
Serial |
3384 |
| Permanent link to this record |
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|
| |
|
Author |
Nistor, L.C.; van Landuyt, J.; Ralchenko, V.G.; Kononenko, T.V.; Obraztsova, E.D.; Strelnitsky, V.E. |
| |
Title |
Direct observation of laser-induced crystallization of a-C : H films |
Type |
A1 Journal article |
| |
Year |
1994 |
Publication |
Applied physics A : materials science & processing |
Abbreviated Journal |
|
| |
Volume |
58 |
Issue |
2 |
Pages |
137-144 |
| |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| |
Abstract |
The post-growth modification of diamond-like amorphous hydrogenated carbon a-C:H films by laser treatment has been studied by transmission electron microscopy and Raman spectroscopy. a-C:H films grown on Si substrates by benzene decomposition in a rf glow discharge were irradiated with 15 ns pulses of a KrF-excimer laser with fluences in the ran e of E = 50-700 mJ/cm(2). At fluences below 100 mJ/cm(2) an increase in the number of graphitic clusters and in their ordering was evidenced from Raman spectra, while the film structure remained amorphous according to electron microscopy and electron diffraction observations. At higher fluences the appearance of diamond particles of 2-7 nm size, embedded into the lower crystallized graphitic matrix, was observed and simultaneously a progressive growth of graphite nanocrystals with dimensions from 2 nm to 4 nm was deduced from Raman measurements. The maximum thickness of the crystallized surface layer (approximate to 400 nm) and the degree of laser annealing are limited by the film ablation which starts at E > 250 mJ/cm(2). The laser-treated areas lose their chemical inertness. In particular, chemical etching in chromium acid becomes possible, which may be used for patterning the highly inert carbon films. |
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Address |
|
| |
Corporate Author |
|
Thesis |
|
| |
Publisher |
|
Place of Publication |
Heidelberg |
Editor |
|
| |
Language |
|
Wos |
A1994MU87700005 |
Publication Date |
2004-10-24 |
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
| |
ISSN |
0721-7250;1432-0630; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| |
Impact Factor |
|
Times cited |
73 |
Open Access |
|
| |
Notes |
|
Approved |
no |
| |
Call Number |
UA @ lucian @ c:irua:99924 |
Serial |
718 |
| Permanent link to this record |
| |
|
| |
|
Author |
Van Tendeloo, G.; Amelinckx, S.; Darriet, B.; Bontchev, R.; Darriet, J.; Weill, F. |
| |
Title |
Structural considerations and high-resolution electron-microscopy observations on LanTin-\deltaO3n(n\geq4\delta) |
Type |
A1 Journal article |
| |
Year |
1994 |
Publication |
Journal of solid state chemistry |
Abbreviated Journal |
J Solid State Chem |
| |
Volume |
108 |
Issue |
2 |
Pages |
314-335 |
| |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| |
Abstract |
|
| |
Address |
|
| |
Corporate Author |
|
Thesis |
|
| |
Publisher |
|
Place of Publication |
London |
Editor |
|
| |
Language |
|
Wos |
A1994MU65200016 |
Publication Date |
2002-10-07 |
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
| |
ISSN |
0022-4596; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| |
Impact Factor |
2.133 |
Times cited |
29 |
Open Access |
|
| |
Notes |
|
Approved |
|
| |
Call Number |
UA @ lucian @ c:irua:99928 |
Serial |
3226 |
| Permanent link to this record |
| |
|
| |
|
Author |
Teodorescu, V.S.; Nistor, L.C.; van Landuyt, J.; Dinescu, M. |
| |
Title |
TEM study of laser induced phase transition in iron thin films |
Type |
A1 Journal article |
| |
Year |
1994 |
Publication |
Materials research bulletin |
Abbreviated Journal |
Mater Res Bull |
| |
Volume |
29 |
Issue |
1 |
Pages |
63-71 |
| |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| |
Abstract |
Laser induced phase transition from b.c.c.(alpha) to f.c.c.(gamma) iron thin films is studied by high resolution TEM. The iron film has been covered on both sides with carbon layers to protect it against oxidation. Single pulse, tau FWHM = 20ns KrF (lambda = 248nm) excimer laser irradiation was performed in air with the film on the substrate. The laser pulse acts like a heat pulse followed by a rapid quenching revealing sequential aspects of the phase transition process. The presence of a fine mixture of the alpha + gamma phases between the alpha and gamma regions of the film has been interpreted as an incomplet transformation. The results are explained by assuming that the transformation took place via a phonon drag mechanism. |
| |
Address |
|
| |
Corporate Author |
|
Thesis |
|
| |
Publisher |
|
Place of Publication |
New York, N.Y. |
Editor |
|
| |
Language |
|
Wos |
A1994ML03000008 |
Publication Date |
2003-06-21 |
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
| |
ISSN |
0025-5408; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| |
Impact Factor |
2.288 |
Times cited |
2 |
Open Access |
|
| |
Notes |
|
Approved |
no |
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UA @ lucian @ c:irua:99945 |
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3488 |
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Author |
Arslan Irmak, E. |
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Title |
Modelling three-dimensional nanoparticle transformations based on quantitative transmission electron microscopy |
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Doctoral thesis |
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2022 |
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169 p. |
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Doctoral thesis; Electron microscopy for materials research (EMAT) |
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Abstract |
Nanomaterials are materials that have at least one dimension in the nanometer length scale, which corresponds to a billionth of a meter. When three dimensions are confined to the nanometer scale, these materials are referred to as nanoparticles. These materials are of great interest since they exhibit unique physical and chemical properties that cannot be observed for bulk systems. Due to their unique and often superior properties, nanomaterials have become central in the field of electronics, catalysis, and medicine. Moreover, they are expected to be one of the most promising systems to tackle many challenges that our society is facing, such as reducing the emission of greenhouse gases and finding effective treatments for cancer. The unique properties of nanomaterials are linked to their size, shape, structure, and composition. If one is able to measure the positions of the atoms, their chemical nature, and the bonding between them, it becomes possible to predict the physicochemical properties of nanomaterials. In this manner, the development of novel nanostructures can be triggered. However, the morphology and structure of nanomaterials are highly sensitive to the conditions for relevant applications, such as elevated temperatures or intense light illumination. Furthermore, any small change in the local structure at higher temperatures or pressures may significantly modify their performance. Hence, three-dimensional (3D) characterization of nanomaterials under application-relevant conditions is important in designing them with desired functional properties for specific applications. Among different structural characterization approaches, transmission electron microscopy (TEM) is one of the most efficient and versatile tools to investigate the structure and composition of nanomaterials since it can provide atomically resolved images, which are sensitive to the local 3D structure of the investigated sample. However, TEM only provides two-dimensional (2D) images of the 3D nanoparticle, which may lead to an incomplete understanding of their structure-property relationship. The most known and powerful technique for the 3D characterization of nanomaterials is electron tomography, where the images of a nanostructured material taken from different directions are mathematically combined to retrieve its 3D structure. Although these experiments are already state-of-the-art, 3D characterization by TEM is typically performed under ultra-high vacuum conditions and at room temperature. Such conditions are unfortunately not sufficient to understand transformations during synthesis or applications of nanomaterials. This limitation can be overcome by in situ TEM where external stimuli, such as heat, gas, and liquids, can be controllably introduced inside the TEM using specialized holders. However, there are some technical limitations to successful perform 3D in situ electron tomography experiments. For example, the long acquisition time required to collect a tilt series limits this technique when one wants to observe 3D dynamic changes with atomic resolution. A solution for this problem is the estimation of the 3D structure of nanomaterials from 2D projection images acquired along a single viewing direction. For this purpose, annular dark field scanning TEM (ADF STEM) imaging mode provides a valuable tool for quantitative structural investigation of nanomaterials from single 2D images due to its thickness and mass sensitivity. For quantitative analysis, an ADF STEM image is considered as a 2D array of pixels where relative variation of pixel intensity values is proportional to the total number of atoms and the atomic number of the elements in the sample. By applying advanced statistical approaches to these images, structural information, such as the number or types of atoms, can be retrieved with high accuracy and precision. The outcome can then be used to build a 3D starting model for energy minimization by atomistic simulations, for example, molecular dynamics simulations or the Monte Carlo method. However, this methodology needs to be further evaluated for in situ experiments. This thesis is devoted to presenting robust approaches to accurately define the 3D atomic structure of nanoparticles under application-relevant conditions and understand the mechanism behind the atomic-scale dynamics in nanoparticles in response to environmental stimuli. |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:188295 |
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7063 |
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