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Author Godefroo, S.; Hayne, M.; Jivanescu, M.; Stesmans, A.; Zacharias, M.; Lebedev, O.I.; Van Tendeloo, G.; Moshchalkov, V.V.
Title Classification and control of the origin of photoluminescence from Si nanocrystals Type A1 Journal article
Year 2008 Publication Nature nanotechnology Abbreviated Journal Nat Nanotechnol
Volume 3 Issue 3 Pages 174-178
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract Silicon dominates the electronics industry, but its poor optical properties mean that III-V compound semiconductors are preferred for photonics applications. Photoluminescence at visible wavelengths was observed from porous Si at room temperature in 1990, but the origin of these photons (do they arise from highly localized defect states or quantum confinement effects?) has been the subject of intense debate ever since. Attention has subsequently shifted from porous Si to Si nanocrystals, but the same fundamental question about the origin of the photoluminescence has remained. Here we show, based on measurements in high magnetic fields, that defects are the dominant source of light from Si nanocrystals. Moreover, we show that it is possible to control the origin of the photoluminescence in a single sample: passivation with hydrogen removes the defects, resulting in photoluminescence from quantum-confined states, but subsequent ultraviolet illumination reintroduces the defects, making them the origin of the light again.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000254743600017 Publication Date 2008-03-02
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1748-3387;1748-3395; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 38.986 Times cited 426 Open Access
Notes Fwo Approved Most recent IF: 38.986; 2008 IF: 20.571
Call Number UA @ lucian @ c:irua:102630 Serial 373
Permanent link to this record
 
 
Author Paul, J.S.; Groothaert, M.H.; Kirschhock, C.E.A.; Lebedev, O.I.; Jacobs, P.A.; Maier, W.F.
Title Novel MoVSbOx-type catalysts for selective isobutane oxidation Type A1 Journal article
Year 2004 Publication Catalysis today T2 – 7th European Workshop Meeting on Selective Oxidation, AUG 31-SEP 04, 2003, Innsbruck, AUSTRIA Abbreviated Journal Catal Today
Volume 91-2 Issue Pages 265-269
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract A new sol-gel synthesis procedure is proposed for the preparation of MoVSbOx catalysts for the selective oxidation of isobutane. Physico-chemical characterization of the materials calcined at 400 degreesC, showed essentially amorphous catalysts, with long-range order. Increase of calcination temperature, however, resulted in the formation of small crystalline regions, confirmed through TEM. EPR measurements on the calcined samples pointed to the presence of isolated and magnetically interacting V(IV) species. The reported catalysts proved to be much more selective for partial oxidation compared to a literature reference catalyst. Furthermore, it is shown that this versatile synthesis recipe forms an excellent start for high-throughput and combinatorial studies. (C) 2004 Elsevier B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000222691000049 Publication Date 2004-05-11
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0920-5861; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 4.636 Times cited 12 Open Access
Notes Approved Most recent IF: 4.636; 2004 IF: 3.108
Call Number UA @ lucian @ c:irua:102761 Serial 2383
Permanent link to this record
 
 
Author Antipov, E.V.; Khasanova, N.R.; Pshirkov, J.S.; Putilin, S.N.; Bougerof, C.; Lebedev, O.I.; Van Tendeloo, G.; Baranov, A.; Park, Y.W.
Title The superconducting bismuth-based mixed oxides Type A1 Journal article
Year 2003 Publication Journal of low temperature physics T2 – International Conference on Physics and Chemistry of Molecular and Oxide, Superconductors (MOS2002), AUG 13-18, 2002, HSINCHU, TAIWAN Abbreviated Journal J Low Temp Phys
Volume 131 Issue 3-4 Pages 575-587
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The present paper describes the synthesis, characterization of mixed-valence bismuthates with 3- or 2-dimensional perovskite-like structures and structural criteria that influence superconductivity in these compounds. Single-phase samples of Sr1-xKxBiO3 were prepared for the broad range of K-content: 0.25 less than or equal to x less than or equal to 0.65. For these bismuthates the symmetry of the structure changes from monoclinic to orthorhombic and finally to tetragonal upon increasing the K-content thus resulting in the decrease of the Bi-O distances and reduction of the network distortions. Superconductivity with maximum T-c = 12K exists in the narrow range (x approximate to 0.5 – 0.6) within the stability field of the tetragonal phase (0.33 less than or equal to x less than or equal to 0.65), when the 3-dimensional octahedral framework has close to the ideal perovskite structure arrangement. At the same time compositions with close to optimal Bi-valence (x = 0.33 and 0.43) do not show any sign of superconductivity, probably, due to structural distortions. The layered type (BaK)(3)Bi2O7 and (Ba,K)(2)BiO4 bismuthates belonging to the A(n+1)B(n)O(3n+1) homologous series were investigated Buckling of the (BiO2) layers in the structure of the n = 2 member was revealed The formation of the n=1 bismuthate was found by Electron Microscopy and X-ray powder diffraction studies. Both types of compounds are considered to be possible candidates for new superconducting materials among bismuthates.
Address
Corporate Author Thesis
Publisher Place of Publication New York Editor
Language Wos 000181768000061 Publication Date 2003-04-07
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-2291; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 1.3 Times cited 3 Open Access
Notes Approved Most recent IF: 1.3; 2003 IF: 1.171
Call Number UA @ lucian @ c:irua:102803 Serial 3597
Permanent link to this record
 
 
Author Farvacque, J.L.; Bougrioua, Z.; Moerman, I.; Van Tendeloo, G.; Lebedev, O.
Title Role of the defect microstructure on the electrical transport properties in undoped and Si-doped GaN grown by LP-MOVPE Type A1 Journal article
Year 1999 Publication Physica: B : condensed matter T2 – 20th International Conference on Defects in Semiconductors (ICDS-20), JUL 26-30, 1999, BERKELEY, CA Abbreviated Journal Physica B
Volume 273-4 Issue Pages 140-143
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Experimental results show that the room-temperature carrier mobility in bulk layers of undoped or Si-doped GaN grown by LP-MOVPE on sapphire substrate shows a sudden increase as soon as the carrier density exceeds a critical value of about 10(18) cm(-3). We show that such a behavior can be theoretically reproduced by assuming that the columnar structure i.e. the dislocation microstructure is responsible for internal electronic barriers. (C) 1999 Elsevier Science B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000084452200031 Publication Date 2002-07-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4526; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 1.386 Times cited 5 Open Access
Notes Approved Most recent IF: 1.386; 1999 IF: 0.725
Call Number UA @ lucian @ c:irua:102892 Serial 2925
Permanent link to this record
 
 
Author Verbist, K.; Lebedev, O.I.; Van Tendeloo, G.; Tafuri, F.; Granozio, F.M.; Di Chiara, A.; Bender, H.
Title A potential method to correlate electrical properties and microstructure of a unique high-Tc superconducting Josephson junction Type A1 Journal article
Year 1999 Publication Applied physics letters Abbreviated Journal Appl Phys Lett
Volume 74 Issue 7 Pages 1024-1026
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract A method to correlate microstructure from cross-section transmission electron microscopy (TEM) investigations and transport properties of a single well characterized high-T-c artificial grain boundary junction is reported. A YBa2Cu3O7-delta 45 degrees twist junction exhibiting the typical phenomenology of high T-c Josephson weak links was employed. The TEM sample preparation is based on focused ion beam etching and allows to easily localize the electron transparent area on a microbridge. The reported technique opens clear perspectives in the determination of the microstructural origin of variations in Josephson junction properties, such as the spread in I-c and IcRN values and the presence of different transport regimes in nominally identical junctions. (C) 1999 American Institute of Physics. [S0003-6951(99)03404-X].
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication New York, N.Y. Editor
Language Wos 000078571400043 Publication Date 2002-07-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6951; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 3.411 Times cited 5 Open Access
Notes Approved Most recent IF: 3.411; 1999 IF: 4.184
Call Number UA @ lucian @ c:irua:102912 Serial 2686
Permanent link to this record
 
 
Author Laffez, P.; Lebedev, O.I.; Ruello, P.; Desfeux, R.; Banerjee, G.; Capon, F.
Title Evidence of strain induced structural change in hetero-epitaxial NdNiO3 thin films with metal-insulator transition Type A1 Journal article
Year 2004 Publication European physical journal: applied physics Abbreviated Journal Eur Phys J-Appl Phys
Volume 25 Issue 1 Pages 25-31
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Neodymium nickelate thin films have been prepared on NdGaO3 substrates by RF magnetron sputtering and post-annealing treatment under oxygen pressure. Transport properties are found to depend strongly on film thickness. Thick films show transport properties close to bulk ceramics, while very thin films exhibit a large transition from metal to insulator which occurs over a wide temperature range with high resistivity. Structure and surface morphology of the films have been investigated by Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM). Thin films (approximate to17 nm) grow heteroepitaxially, while thicker films (approximate to73 nm) show a granular structure. The thinnest sample suggests a symmetry change induced by the epitaxial strain of the substrate. This paper discusses the relationship between microstructure and transport properties.
Address
Corporate Author Thesis
Publisher Place of Publication Paris Editor
Language Wos 000187286000003 Publication Date 2003-12-15
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1286-0042;1286-0050; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 0.684 Times cited 12 Open Access
Notes Approved Most recent IF: 0.684; 2004 IF: 0.745
Call Number UA @ lucian @ c:irua:103256 Serial 1096
Permanent link to this record
 
 
Author Linssen, T.; Cassiers, K.; Cool, P.; Lebedev, O.; Whittaker, A.; Vansant, E.F.
Title Physicochemical and structural characterization of mesoporous aluminosilicates synthesized from leached saponite with additional aluminum incorporation Type A1 Journal article
Year 2003 Publication Chemistry of materials Abbreviated Journal Chem Mater
Volume 15 Issue 25 Pages 4863-4873
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA)
Abstract A thorough investigation was performed on the physical (mechanical, thermal, and hydrothermal stability) and chemical (ion exchange capacity and silanol number) characteristics of aluminosilicate FSMs, synthesized via a new successful short-time synthesis route using leached saponite and a low concentration of CTAB. Moreover, the influence of an additional Al incorporation, utilizing different aluminum sources, on the structure of the FSM derived from saponite is studied. A mesoporous aluminosilicate with a low Si/Al ratio of 12.8 is synthesized, and still has a very large surface area of 1130 m(2)/g and pore volume of 0.92 cm(3)/g. The aluminum-containing samples all have a high cation exchange capacity of around 1 mmol/9 while they still have a silanol number of about 0.9 OH/nm(2); both characteristics being interesting for high-yield postsynthesis modification reactions. Finally, a study is performed on the transformation of the aluminosilicates into their Bronsted acid form via the exchange with ammonium ions and a consecutive heat treatment.
Address
Corporate Author Thesis
Publisher Place of Publication Washington, D.C. Editor
Language Wos 000187250800026 Publication Date 2003-12-09
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0897-4756;1520-5002; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 9.466 Times cited 11 Open Access
Notes Approved Most recent IF: 9.466; 2003 IF: 4.374
Call Number UA @ lucian @ c:irua:103265 Serial 2618
Permanent link to this record
 
 
Author Cassiers, K.; van der Voort, P.; Linssen, T.; Vansant, E.F.; Lebedev, O.; van Landuyt, J.
Title A counterion-catalyzed (S0H+)(X-I+) pathway toward heat- and steam-stable mesostructured silica assembled from amines in acidic conditions Type A1 Journal article
Year 2003 Publication The journal of physical chemistry : B : condensed matter, materials, surfaces, interfaces and biophysical Abbreviated Journal J Phys Chem B
Volume 107 Issue 16 Pages 3690-3696
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA)
Abstract An alternative pathway to assemble mesoporous molecular sieve silicas is developed using nonionic alkylamines and N,N-dimethylalkylamines (SO) as structure-directing agents in acidic conditions. The synthesized mesostructures possess wormhole-like frameworks with pore sizes and pore volumes in the range of 20-90 Angstrom and 0.5-1.3 cm(3)/g, respectively. The formation of the mesophase is controlled by a counterion-mediated mechanism of the type (S(0)H(+))(X(-)I(+)), where S(0)H(+) are protonated water molecules that are hydrogen bonded to the lone electron pairs on the amine surfactant headgroups (S(0)H(+)), X(-) is the counteranion originating from the acid, and I(+) are the positively charged (protonated) silicate species. We found that the stronger the ion X(-) is bonded to S(0)H(+), the more it catalyzes the silica condensation into (S(0)H(+))(X(-)I(+)). Br(-) is shown to be a strong binding anion and therefore a fast silica polymerization promoter compared to Cl(-) resulting in the formation of a higher quality mesophase for the Br(-) syntheses. We also showed that the polymerization rate of the silica, dictated by the counterion, controls the morphology of the mesostructures from nonuniform agglomerated blocks in the case of Br(-) syntheses to spherical particles for the Cl(-) syntheses. Next to many benefits such as low temperature, short synthesis time, and the use of inexpensive, nontoxic, and easily extractable amine templates, the developed materials have a remarkable higher thermal and hydrothermal stability compared to hexagonal mesoporous silica, which is also prepared with nonionic amines but formed through the S(0)I(0) mechanism.
Address
Corporate Author Thesis
Publisher Place of Publication Washington, D.C. Editor
Language Wos 000182350200005 Publication Date 2003-04-17
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1520-6106;1520-5207; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 3.177 Times cited 9 Open Access
Notes Approved Most recent IF: 3.177; 2003 IF: 3.679
Call Number UA @ lucian @ c:irua:103300 Serial 24
Permanent link to this record
 
 
Author Simoen, E.; Loo, R.; Claeys, C.; de Gryse, O.; Clauws, P.; van Landuyt, J.; Lebedev, O.
Title Optical spectroscopy of oxygen precipitates in heavily doped p-type silicon Type A1 Journal article
Year 2002 Publication Journal of physics : condensed matter T2 – Conference on Extended Defects in Semiconductors (EDS 2002), JUN 01-06, 2002, BOLOGNA, ITALY Abbreviated Journal J Phys-Condens Mat
Volume 14 Issue 48 Pages 13185-13193
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Results are presented on the photoluminescence (PL) characterization of heavily doped p(+) Czochralski silicon, which has been subjected to a two-step, oxygen precipitation heat treatment. It will be shown that the presence of oxygen precipitates gives rise to the D1, D2 and D5 lines, where the energy of the D1 line shifts to lower values for a stronger degree of precipitation. The occurrence of these PL features is also a function of the boron concentration in the p(+) material. The PL results are compared with Fourier transform infrared absorption data and with transmission electron microscope, results. From this, it is concluded that PL has a good potential for use in the assessment of oxygen precipitation in heavily doped silicon.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000180091100068 Publication Date 2002-11-23
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0953-8984; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 2.649 Times cited 3 Open Access
Notes Approved Most recent IF: 2.649; 2002 IF: 1.775
Call Number UA @ lucian @ c:irua:103326 Serial 2477
Permanent link to this record
 
 
Author Antipov, E.V.; Khasanova, N.R.; Pshirkov, J.S.; Putilin, S.N.; Bougerol, C.; Lebedev, O.I.; Van Tendeloo, G.; Baranov, A.N.; Park, Y.W.
Title The superconducting bismuth-based mixed oxides Type A1 Journal article
Year 2002 Publication Current applied physics T2 – QTSM and QFS 02 Symposium, MAY 08-10, 2002, SEOUL, SOUTH KOREA Abbreviated Journal Curr Appl Phys
Volume 2 Issue 5 Pages 425-430
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The present paper describes the synthesis, characterization of mixed-valence bismuthates with three- or two-dimensional perovskite-like structures and structural criteria that influence superconductivity in these compounds. Single-phase samples of Sr1-xKxBiO3 were prepared for the broad range of K-content: 0.25 less than or equal to x less than or equal to 0.65. For these bismuthates the symmetry of the structure changes from monoclinic to orthorhombic and finally to tetragonal upon increasing the K-content thus resulting in the decrease of the Bi-O distances and reduction of the network distortions. Superconductivity with maximum T-c = 12 K exists in the narrow range (x approximate to 0.5-0.6) within the stability field of the tetragonal phase (0.33 less than or equal to x less than or equal to 0.65), when the three-dimensional octahedral framework has close to the ideal perovskite structure arrangement. The layered type (Ba,K)(3)Bi2O7 and (Ba,K)(2)BiO4 bismuthates belonging to the A(n+1)B(n)O(3n+1) homologous series were investigated. Buckling of the (BiO2) layers in the structure of the n = 2 member occurs due to the ordering of alkaline- and alkaline-earth cations between two independent positions. The formation of the one-layer bismuthate was revealed by Electron Microscopy and XRPD studies. Both types of compounds are considered to be possible candidates for new superconducting materials among bismuthates. (C) 2002 Published by Elsevier Science B.V.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000179330900015 Publication Date 2002-11-04
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1567-1739; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 1.971 Times cited 2 Open Access
Notes Approved Most recent IF: 1.971; 2002 IF: NA
Call Number UA @ lucian @ c:irua:103336 Serial 3598
Permanent link to this record
 
 
Author Gryse, O.D.; Clauws, P.; van Landuyt, J.; Lebedev, O.; Claeys, C.; Simoen, E.; Vanhellemont, J.
Title Oxide phase determination in silicon using infrared spectroscopy and transmission electron microscopy techniques Type A1 Journal article
Year 2002 Publication Journal of applied physics Abbreviated Journal J Appl Phys
Volume 91 Issue 4 Pages 2493-2498
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Infrared absorption spectra of polyhedral and platelet oxygen precipitates in silicon are analyzed using a modified Day-Thorpe approach [J. Phys.: Condens. Matter 11, 2551 (1999)]. The aspect ratio of the precipitates is determined by transmission electron microscopy analysis. The reduced spectral function and the stoichiometry of the precipitate are extracted from the absorption spectra and the amount of precipitated interstitial oxygen. The experimental absorption spectra can be divided in a set with a Frohlich frequency of around 1100 cm(-1) and in a set with a Frohlich frequency between 1110 and 1120 cm(-1). It is shown that the shift in the Frohlich frequency is not due to a differing stoichiometry, but to the detailed structure of the reduced spectral function. Inverse modeling of the spectra suggests that the oxide precipitates consist of substoichiometric SiOgamma with gamma=1.17+/-0.14. (C) 2002 American Institute of Physics.
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication New York, N.Y. Editor
Language Wos 000173553800114 Publication Date 2002-07-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-8979; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 2.068 Times cited 27 Open Access
Notes Approved Most recent IF: 2.068; 2002 IF: 2.281
Call Number UA @ lucian @ c:irua:103372 Serial 2542
Permanent link to this record
 
 
Author de Gryse, O.; Clauws, P.; Lebedev, O.; van Landuyt, J.; Vanhellemont, J.; Claeys, C.; Simoen, E.
Title Chemical and structural characterization of oxygen precipitates in silicon by infrared spectroscopy and TEM Type A1 Journal article
Year 2001 Publication Physica: B : condensed matter T2 – 21st International Conference on Defects in Semiconductors, JUL 16-20, 2001, GIESSEN, GERMANY Abbreviated Journal Physica B
Volume 308 Issue Pages 294-297
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Infrared absorption spectra of polyhedral and platelet oxygen precipitates are analyzed using a modified Day-Thorpe approach (J. Phys.: Condens. Matter 11 (1999) 2551). The aspect ratio has been determined by TEM measurements. The reduced spectral function and the stoichiometry are extracted from the absorption spectra and the concentration of precipitated interstitial oxygen. One set of spectra reveal a Frohlich frequency around 1100 cm(-1) and another around 1110-1120 cm(-1). It is shown that the shift in the Frohlich frequency is not due to a different stoichiometry, but due to the detailed structure in the reduced spectral function. The oxygen precipitates consist of SiO. with gammaapproximate to1.1-1.2+/-0.1. (C) 2001 Elsevier Science B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Elsevier science bv Place of Publication Amsterdam Editor
Language Wos 000173660100073 Publication Date 2002-10-15
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4526; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 1.386 Times cited 3 Open Access
Notes Approved Most recent IF: 1.386; 2001 IF: 0.663
Call Number UA @ lucian @ c:irua:103389 Serial 345
Permanent link to this record
 
 
Author Fedina, L.; Lebedev, O.I.; Van Tendeloo, G.; van Landuyt, J.; Mironov, O.A.; Parker, E.H.C.
Title In situ HREM irradiation study of point-defect clustering in MBE-grown strained Si1-xGex/(001)Si structures Type A1 Journal article
Year 2000 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 61 Issue 15 Pages 10336-10345
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract We present a detailed analysis of the point-defect clustering in strained Si/Si(1-x)Ge(x)/(001)Si structures, including the interaction of the point defects with the strained interfaces and the sample surface during 400 kV electron irradiation at room temperature. Point-defect cluster formation is very sensitive to the type and magnitude of the strain in the Si and Si(1-x)Ge(x) layers. A small compressive strain (-0.3%) in the SiGe alloy causes an aggregation of vacancies in the form of metastable [110]-oriented chains. They are located on {113} planes and further recombine with interstitials. Tensile strain in the Si layer causes an aggregation of interstitial atoms in the forms of additional [110] rows which are inserted on {113} planes with [001]-split configurations. The chainlike configurations are characterized by a large outward lattice relaxation for interstitial rows (0.13 +/-0.01 nm) and a very small inward relaxation for vacancy chains (0.02+/-0.01 nm). A compressive strain higher than -0.5% strongly decreases point-defect generation inside the strained SiGe alloy due to the large positive value of the formation volume of a Frenkel pair. This leads to the suppression of point-defect clustering in a strained SiGe alloy so that SiGe relaxes via a diffusion of vacancies from the Si layer, giving rise to an intermixing at the Si/SiGe interface. In material with a 0.9% misfit a strongly increased flow of vacancies from the Si layer to the SiGe layer and an increased biaxial strain in SiGe bath promote the preferential aggregation of vacancies in the (001) plane, which relaxes to form intrinsic 60 degrees dislocation loops.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000086606200082 Publication Date 2002-07-27
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829;1095-3795; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 27 Open Access
Notes Conference Name: Microsc. Semicond. Mater. Conf. Approved Most recent IF: 3.836; 2000 IF: NA
Call Number UA @ lucian @ c:irua:103456 Serial 1577
Permanent link to this record
 
 
Author Habermeier, H.U.; Razavi, F.; Lebedev, O.; Gross, G.M.; Praus, R.; Zhang, P.X.
Title Correlation of microstructure and magnetotransport properties of epitaxially grown La-Ca-Mn-O3 thin films Type A1 Journal article
Year 1999 Publication Physica status solidi: B: basic research T2 – International Conference on Solid State Spectroscopy – (ICSSS), SEP 05-07, 1999, SCHWABISCH-GMUND, GERMANY Abbreviated Journal Phys Status Solidi B
Volume 215 Issue 1 Pages 679-683
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract We have investigated epitaxially grown single-crystalline Ca-doped LaMnO3 thin films using the pulsed laser deposition technique in a case study aimed to explore the possibilities buried in epitaxial stress tailoring in order to control the transport properties of CMR materials beyond the limits set by equilibrium thermodynamics. Depending on the film thickness there is an abrupt transition from pseudomorphic to epitaxial granular growth observable which is related to the epitaxial strain of the films. This is associated with microscopic stress relaxation and leads to well controllable modifications of the atomic arrangements of the Mn-O sublattice in the films. Due to the interrelation of double exchange, spin-, charge- and orbital ordering and the Jahn-Teller effect mediated coupling of the electronic system to the crystal lattice, the magnetotransport properties of the firms can be modified in a controllable way.
Address
Corporate Author Thesis
Publisher Place of Publication Berlin Editor
Language Wos 000082487800110 Publication Date 2002-09-10
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0370-1972;1521-3951; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 1.674 Times cited 3 Open Access
Notes Approved Most recent IF: 1.674; 1999 IF: 0.978
Call Number UA @ lucian @ c:irua:103489 Serial 527
Permanent link to this record
 
 
Author Lukashin, A.V.; Eliseev, A.A.; Zhuravleva, N.G.; Vertegel, A.A.; Tretyakov, Y.D.; Lebedev, O.I.; Van Tendeloo, G.
Title One-step synthesis of shelled PbS nanoparticles in a layered double hydroxide matrix Type A1 Journal article
Year 2004 Publication Mendeleev communications Abbreviated Journal Mendeleev Commun
Volume Issue 4 Pages 174-176
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The one-step preparation of capped PbS nanoparticles in an inorganic matrix via UV-induced decomposition of lead thiosulfate complexes intercalated into a hydrotalcite-type layered double hydroxide is reported.
Address
Corporate Author Thesis
Publisher Place of Publication Cambridge Editor
Language Wos 000224247100025 Publication Date 2004-09-09
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0959-9436; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 1.741 Times cited 9 Open Access
Notes Approved Most recent IF: 1.741; 2004 IF: 0.640
Call Number UA @ lucian @ c:irua:103735 Serial 2468
Permanent link to this record
 
 
Author de Gryse, O.; Clauws, P.; Vanhellemont, J.; Lebedev, O.I.; van Landuyt, J.; Simoen, E.; Claeys, C.
Title Characterization of oxide precipitates in heavily B-doped silicon by infrared spectroscopy Type A1 Journal article
Year 2004 Publication Journal of the electrochemical society Abbreviated Journal J Electrochem Soc
Volume 151 Issue 9 Pages G598-G605
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Infrared absorption spectra of oxygen precipitates in boron-doped silicon with a boron concentration between 10(17) and 10(19) cm(-3) are analyzed, applying the spectral function representation of composite materials. The aspect ratio of the platelet precipitates is determined by transmission electron microscopy measurements. The analysis shows that in samples with moderate doping levels (<10(18) B cm(-3)) SiOγ precipitates are formed with the same composition as in the lightly doped case. In the heavily boron-doped (>10(18) cm(-3)) samples, however, the measured spectra of the precipitates are consistent with a mixture of SiO2 and B2O3, with a volume fraction of B2O3 as high as 0.41 in the most heavily doped case. (C) 2004 The Electrochemical Society.
Address
Corporate Author Thesis
Publisher Place of Publication New York, N.Y. Editor
Language Wos 000223622000072 Publication Date 2004-08-30
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0013-4651; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 3.259 Times cited 13 Open Access
Notes Fwo; Iuap P5/01 Approved Most recent IF: 3.259; 2004 IF: 2.356
Call Number UA @ lucian @ c:irua:103760 Serial 330
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Author de Gryse, O.; Vanhellemont, J.; Clauws, P.; Lebedev, O.; van Landuyt, J.; Simoen, E.; Claeys, C.
Title A novel approach to analyse FTIR spectra of precipitates in boron-doped silicon Type A1 Journal article
Year 2003 Publication Physica: B : condensed matter T2 – 22nd International Conference on Defects in Semiconductors (ICDS-22), JUL 28-AUG 01, 2003, UNIV AARHUS, AARHUS, DENMARK Abbreviated Journal Physica B
Volume 340 Issue Pages 1013-1017
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Infrared absorption spectra of composite precipitates are analysed with a modified Day-Thorpe algorithm, assuming a precipitated phase consisting of a mixture of two components with known optical properties. Additional constraints are introduced when solving the model equations by using a priori knowledge making the algorithm more reliable. It is shown that this novel approach allows determining both morphology and composition of precipitates. The method is applied to characterise oxide precipitates in boron-doped silicon. The results indicate that for the resistivity range above 60 mOmegacm, the precipitated phase is most probably SiO1.17+/-0.14, while for resistivities below 20 mOmega cm, precipitates consist of a SiO2/B2O3 composite with a large volume fraction of B(2)0(3) (up to 40% for 8 mOmegacm material). (C) 2003 Elsevier B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000188300200213 Publication Date 2003-11-24
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4526; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 1.386 Times cited 4 Open Access
Notes Approved Most recent IF: 1.386; 2003 IF: 0.908
Call Number UA @ lucian @ c:irua:103784 Serial 25
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Author Blumenau, A.T.; Jones, R.; Frauenheim, T.; Willems, B.; Lebedev, O.I.; Van Tendeloo, G.; Fisher, D.; Martineau, P.M.
Title Dislocations in diamond : dissociation into partials and their glide motion Type A1 Journal article
Year 2003 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 68 Issue 1 Pages 014115-14119
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The dissociation of 60degrees and screw dislocations in diamond is modeled in an approach combining isotropic elasticity theory with ab initio-based tight-binding total-energy calculations. Both dislocations are found to dissociate with a substantial lowering of their line energies. For the 60degrees dislocation, however, an energy barrier to dissociation is found. We investigate the core structure of a screw dislocation distinguishing “shuffle,” “mixed,” and “glide” cores. The latter is found to be the most stable undissociated screw dislocation. Further, the glide motion of 90degrees and 30degrees partials is discussed in terms of a process involving the thermal formation and subsequent migration of kinks along the dislocation line. The calculated activation barriers to dislocation motion show that the 30degrees partial is less mobile than the 90degrees partial. Finally, high-resolution electron microscopy is performed on high-temperature, high-pressure annealed natural brown diamond, allowing the core regions of 60degrees dislocations to be imaged. The majority of dislocations are found to be dissociated. However, in some cases, undissociated 60degrees dislocations were also observed.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000184582900050 Publication Date 2003-08-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829;1095-3795; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 39 Open Access
Notes Approved Most recent IF: 3.836; 2003 IF: NA
Call Number UA @ lucian @ c:irua:103800 Serial 734
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Author Wang, Z.-H.; Kronmüller, H.; Lebedev, O.I.; Gross, G.M.; Razavi, F.S.; Habermeier, H.U.; Shen, B.G.
Title Phase transition and magnetic anisotropy of (La,Sr)MnO3 thin films Type A1 Journal article
Year 2002 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 65 Issue 5 Pages 054411-54416
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The magnetic proper-ties and their correlation with the microstructure and electrical transport are investigated in La0.88Sr0.1MnO3 films grown on (100)SrTiO3 Single crystal substrates with thickness ranging from 100 to 2500 Angstrom. The ultrathin film (t = 100 Angstrom) has a single ferromagnetic transition (FMT) at T-c of 250 K, whereas the thicker films exhibit two FMTs, with the main one at a lowered T-c of 200 K while the minor one around 300 K. Furthermore, a thickness dependent magnetic anisotropy has been found, strongly indicating the existence of strain effect, which is also revealed by the transmission electron microscopy study. The suppressed Jahn-Teller distortion (JTD) by the epitaxial strain, and the recovered JTD due to the strain relexation are suggested to explain the metallic behavior in thin films and the insulating behavior in the thick film (t = 2500 Angstrom), repectively.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000173647000058 Publication Date 2002-07-27
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829;1095-3795; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 23 Open Access
Notes Approved Most recent IF: 3.836; 2002 IF: NA
Call Number UA @ lucian @ c:irua:103883 Serial 2592
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Author Sudheendra, L.; Moshnyaga, V.; Lebedev, O.I.; Gehrke, K.; Belenciuc, A.; Shapoval, O.; Van Tendeloo, G.; Samwer, K.
Title A-site ordering and stripe phases in manganite films Type A1 Journal article
Year 2008 Publication Physica: B : condensed matter T2 – International Conference on Strongly Correlated Electron Systems (SCES, 2007), MAY 13-18, 2007, Houston, TX Abbreviated Journal Physica B
Volume 403 Issue 5-9 Pages 1645-1646
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Insulating and metallic stripes above and below the Curie temperature, T-C, respectively, were observed by a high-resolution scanning tunneling microscopy (STM) and/or spectroscopy (STS) in A-site ordered and macroscopically strain free epitaxial La0.75Ca0.25MnO3 film grown on MgO substrate. The “insulating” stripes were found to be incommensurable to the lattice and aligned along (110) direction. Metallic stripes were commensurable with periodicity 2a(p)similar to 0.8 nm and aligned parallel to the crystallographic a/b-axis. Formation of these stripes involves competing charge, orbital, and lattice orders and is an outcome of an overlapping of electron wave functions mediated by the local lattice-strain distribution, existed even in A-site ordered film due to the difference in cation radii of La and Ca. (C) 2007 Elsevier B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000254689900330 Publication Date 2007-11-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4526; ISBN Additional Links (up) UA library record; WoS full record
Impact Factor 1.386 Times cited Open Access
Notes Approved Most recent IF: 1.386; 2008 IF: 0.822
Call Number UA @ lucian @ c:irua:104031 Serial 26
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Author Krsmanovic, R.; Morozov, V.A.; Lebedev, O.I.; Polizzi, S.; Speghini, A.; Bettinelli, M.; Van Tendeloo, G.
Title Structural and luminescence investigation on gadolinium gallium garnet nanocrystalline powders prepared by solution combustion synthesis Type A1 Journal article
Year 2007 Publication Nanotechnology Abbreviated Journal Nanotechnology
Volume 18 Issue 32 Pages 325604-325609
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract Nanocrystalline powders of undoped and lanthanide (Pr3+, Tm3+)- doped gadolinium gallium garnet, Gd3Ga5O12 (GGG), were prepared by propellant synthesis and studied by x-ray powder diffraction (XRD), electron diffraction (ED), high-resolution electron microscopy (HREM) and luminescence spectroscopy. The x-ray diffraction patterns of the GGG samples were analysed using the Rietveld method. The Rietveld refinement reveals the existence of two garnet-type phases: both are cubic (space group Ia $(3) over bar $d) with a slightly different lattice parameter and probably a slightly different composition. Electron diffraction and electron microscopy measurements confirm the x-ray diffraction results. EDX measurements for lanthanide-doped samples show that stable solid solutions with composition Gd(3-x)Ln(x)Ga(5)O(12), x approximate to 0.3 ( Ln = Pr; Tm) have been obtained. The luminescence properties of the Tm3+ -doped nanocrystalline GGG samples were measured and analysed.
Address
Corporate Author Thesis
Publisher Place of Publication Bristol Editor
Language Wos 000248231300010 Publication Date 2007-07-14
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0957-4484;1361-6528; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 3.44 Times cited 33 Open Access
Notes Iap5-01 Approved Most recent IF: 3.44; 2007 IF: 3.310
Call Number UA @ lucian @ c:irua:104042 Serial 3195
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Author Ghekiere, P.; Mahieu, S.; De Winter, G.; De Gryse, R.; Depla, D.; Lebedev, O.I.
Title Growth mechanism of biaxially aligned magnesium oxide deposited by unbalanced magnetron sputtering Type A1 Journal article
Year 2005 Publication Diffusion and defect data : solid state data : part B : solid state phenomena T2 – 2nd International Conference on Texture and Anisotropy of Polycrystals, JUL 07-09, 2004, Metz, FRANCE Abbreviated Journal
Volume 105 Issue Pages 433-438
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract For many years magnesium oxide (MgO) has been a topic of research as buffer layer for high-temperature superconducting copper oxides and as protective layer in plasma display panels. Since epitaxial growth of MgO is expensive, time consuming and size restricted, other techniques have been developed to grow highly oriented MgO layers for industrial processes. MgO thin films were deposited on a tilted polycrystalline substrate by reactive sputtering using an unbalanced magnetron. By varying different deposition parameters, it is possible to grow biaxially aligned MgO layers, i.e. layers with both out-of-plane and in-plane alignment. XRD measurements were performed to examine the crystallographic structure of the thin film. The preferential out-of-plane orientation is analysed by angular scans using the peak intensity of different reflections while the in-plane orientation is determined by (002) pole figures. Fully [111] out-of-plane oriented layers were grown with a strong in-plane alignment. SEM and TEM measurements were performed to reveal the topographical and cross-sectional microstructure and to investigate the texture evolution of the MgO layers. Evolutionary columnar growth and a roof-tile surface have been observed.
Address
Corporate Author Thesis
Publisher Place of Publication Vaduz Editor
Language Wos 000230478000069 Publication Date 2009-03-16
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1662-9779; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor Times cited 5 Open Access
Notes Approved Most recent IF: NA
Call Number UA @ lucian @ c:irua:104085 Serial 1392
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Author Maccato, C.; Simon, Q.; Carraro, G.; Barreca, D.; Gasparotto, A.; Lebedev, O.I.; Turner, S.; Van Tendeloo, G.
Title Zinc and copper oxides functionalized with metal nanoparticles : an insight into their nano-organization Type A1 Journal article
Year 2012 Publication Journal of advanced microscopy research Abbreviated Journal
Volume 7 Issue 2 Pages 84-90
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Ag/ZnO and Au/CuxO (x = 1, 2) nanocomposites supported on Si(100) and polycrystalline Al2O3 were synthesised by hybrid approaches, combining chemical vapor deposition (either thermal or plasma-assisted) of host oxide matrices and subsequent radio frequency-sputtering of guest metal particles. The influence of the adopted synthetic parameters on the nanocomposite morphological and compositional features was investigated by field emission-scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. Results confirm the synthesis of ZnO and CuxO nanoarchitectures, characterized by a tailored morphology and an intimate metal/oxide contact. A careful control of the processing conditions enabled a fine tuning of the mutual constituent distribution, opening thus attractive perspectives for the engineering of advanced nanomaterials.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos Publication Date 2012-12-04
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2156-7573;2156-7581; ISBN Additional Links (up) UA library record
Impact Factor Times cited Open Access
Notes Esteem Approved Most recent IF: NA
Call Number UA @ lucian @ c:irua:105298 Serial 3932
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Author Turner, S.; Lebedev, O.I.; Verbeeck, J.; Gehrke, K.; Moshnyaga, V.; Van Tendeloo, G.
Title Structural phase transition and spontaneous interface reconstruction in La2/3Ca1/3MnO3/BaTiO3 superlattices Type A1 Journal article
Year 2013 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 87 Issue 3 Pages 035418-8
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract (La2/3Ca1/3MnO3)n/(BaTiO3)m (LCMOn/BTOm) superlattices on MgO and SrTiO3 substrates with different layer thicknesses (n = 10, 38, 40 and m = 5, 18, 20) have been grown by metal organic aerosol deposition (MAD) and have been fully characterized down to the atomic scale to study the interface characteristics. Scanning transmission electron microscopy combined with spatially resolved electron energy-loss spectroscopy provides clear evidence for the existence of atomically sharp interfaces in MAD grown films, which exhibit epitaxial growth conditions, a uniform normal strain, and a fully oxidized state. Below a critical layer thickness the LCMO structure is found to change from the bulk Pnma symmetry to a pseudocubic R3̅ c symmetry. An atomically flat interface reconstruction consisting of a single Ca-rich atomic layer is observed on the compressively strained BTO on LCMO interface, which is thought to partially neutralize the total charge from the alternating polar atomic layers in LCMO as well as relieving strain at the interface. No interface reconstruction is observed at the tensile strained LCMO on BTO interface.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000313940400008 Publication Date 2013-01-23
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 12 Open Access
Notes FWO; Hercules; Countatoms Approved Most recent IF: 3.836; 2013 IF: 3.664
Call Number UA @ lucian @ c:irua:106180 Serial 3245
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Author Maignan, A.; Singh, K.; Simon, C.; Lebedev, O.I.; Martin, C.; Tan, H.; Verbeeck, J.; Van Tendeloo, G.
Title Magnetic and magnetodielectric properties of erbium iron garnet ceramic Type A1 Journal article
Year 2013 Publication Journal of applied physics Abbreviated Journal J Appl Phys
Volume 113 Issue 3 Pages 033905-5
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract An Er3Fe5O12 ceramic has been sintered in oxygen atmosphere at 1400 °C for dielectric measurements. Its structural quality at room temperature has been checked by combining transmission electron microscopy and X-ray diffraction. It crystallizes in the cubic space group Ia3d with a = 12.3488(1). The dielectric permittivity ([variantgreekepsilon]′) and losses (tan δ) measurements as a function of temperature reveal the existence of two anomalies, a broad one between 110 K and 80 K, attributed to the Er3+ spin reorientation, and a second sharper feature at about 45 K associated to the appearance of irreversibility on the magnetic susceptibility curves. In contrast to the lack of magnetic field impact on [variantgreekepsilon]′ for the former anomaly, a complex magnetic field effect has been evidenced below 45 K. The isothermal [variantgreekepsilon]′(H) curves show the existence of positive magnetodielectric effect, reaching a maximum of 0.14% at 3 T and 10 K. Its magnitude decreases as H is further increased. Interestingly, for the lowest H values, a linear regime in the [variantgreekepsilon]′(H) curve is observed. From this experimental study, it is concluded that the [variantgreekepsilon]′ anomaly, starting above the compensation temperature Tc (75 K) and driven by the internal magnetic field, is not sensitive to an applied external magnetic field. Thus, below 45 K, it is the magnetic structure which is responsible for the coupling between spin and charge in this iron garnet.
Address
Corporate Author Thesis
Publisher American Institute of Physics Place of Publication New York, N.Y. Editor
Language Wos 000313670600042 Publication Date 2013-01-16
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-8979; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 2.068 Times cited 15 Open Access
Notes Vortex; Countatoms ECASJO_; Approved Most recent IF: 2.068; 2013 IF: 2.185
Call Number UA @ lucian @ c:irua:106182UA @ admin @ c:irua:106182 Serial 1861
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Author Ding, J.F.; Lebedev, O.I.; Turner, S.; Tian, Y.F.; Hu, W.J.; Seo, J.W.; Panagopoulos, C.; Prellier, W.; Van Tendeloo, G.; Wu, T.
Title Interfacial spin glass state and exchange bias in manganite bilayers with competing magnetic orders Type A1 Journal article
Year 2013 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 87 Issue 5 Pages 054428-7
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The magnetic properties of manganite bilayers composed of G-type antiferromagnetic (AFM) SrMnO3 and double-exchange ferromagnetic (FM) La0.7Sr0.3MnO3 are studied. A spin-glass state is observed as a result of competing magnetic orders and spin frustration at the La0.7Sr0.3MnO3/SrMnO3 interface. The dependence of the irreversible temperature on the cooling magnetic field follows the Almeida-Thouless line. Although an ideal G-type AFM SrMnO3 is featured with a compensated spin configuration, the bilayers exhibit exchange bias below the spin glass freezing temperature, which is much lower than the Néel temperature of SMO, indicating that the exchange bias is strongly correlated with the spin glass state. The results indicate that the spin frustration that originates from the competition between the AFM super-exchange and the FM double-exchange interactions can induce a strong magnetic anisotropy at the La0.7Sr0.3MnO3/SrMnO3 interface.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000315271200002 Publication Date 2013-02-22
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 98 Open Access
Notes FWO; COUNTATOMS; Hercules Approved Most recent IF: 3.836; 2013 IF: 3.664
Call Number UA @ lucian @ c:irua:107349 Serial 1696
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Author Carraro, G.; Maccato, C.; Bontempi, E.; Gasparotto, A.; Lebedev, O.I.; Turner, S.; Depero, L.E.; Van Tendeloo, G.; Barreca, D.
Title Insights on growth and nanoscopic investigation of uncommon iron oxide polymorphs Type A1 Journal article
Year 2013 Publication European journal of inorganic chemistry Abbreviated Journal Eur J Inorg Chem
Volume Issue 31 Pages 5454-5461
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Si(100)-supported Fe2O3 nanomaterials were developed by a chemical vapor deposition (CVD) approach. The syntheses, which were performed at temperatures between 400 and 550 °C, selectively yielded the scarcely studied β- and ϵ-Fe2O3 polymorphs under O2 or O2 + H2O reaction environments, respectively. Correspondingly, the observed morphology underwent a progressive evolution from interconnected nanopyramids to vertically aligned nanorods. The present study aims to provide novel insights into Fe2O3 nano-organization by a systematic investigation of the system structure/morphology and of their interrelations with growth conditions. In particular, for the first time, the β- and ϵ-Fe2O3 preparation process has been accompanied by a thorough multitechnique investigation, which, beyond X-ray photoelectron spectroscopy (XPS) and field-emission scanning electron microscopy (FESEM), is carried out by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDXS), atomic force microscopy (AFM), high-resolution transmission electron microscopy (HRTEM), electron diffraction (ED), scanning TEM electron energy-loss spectroscopy (STEM-EELS), and high-angle annular dark-field STEM (HAADF-STEM). Remarkably, the target materials showed a high structural and compositional homogeneity throughout the whole thickness of the nanodeposit. In particular, spatially resolved EELS chemical maps through the spectrum imaging (SI) technique enabled us to gain important information on the local Fe coordination, which is of crucial importance in determining the system reactivity. The described preparation method is in fact a powerful tool to simultaneously tailor phase composition and morphology of iron(III) oxide nanomaterials, the potential applications of which include photocatalysis, magnetic devices, gas sensors, and anodes for Li-ion batteries.
Address
Corporate Author Thesis
Publisher Place of Publication Weinheim Editor
Language Wos 000330567000009 Publication Date 2013-10-08
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-1948; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 2.444 Times cited 18 Open Access
Notes Fwo; Countatoms Approved Most recent IF: 2.444; 2013 IF: 2.965
Call Number UA @ lucian @ c:irua:110946 Serial 1676
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Author Carraro, G.; Gasparotto, A.; Maccato, C.; Bontempi, E.; Lebedev, O.I.; Turner, S.; Sada, C.; Depero, L.E.; Van Tendeloo, G.; Barreca, D.
Title Fluorine doped Fe2O3 nanostructures by a one-pot plasma-assisted strategy Type A1 Journal article
Year 2013 Publication RSC advances Abbreviated Journal Rsc Adv
Volume 3 Issue 45 Pages 23762-23768
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The present work reports on the synthesis of fluorine doped Fe2O3 nanomaterials by a single-step plasma enhanced-chemical vapor deposition (PE-CVD) strategy. In particular, Fe(hfa)2TMEDA (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA = N,N,N′,N′-tetramethylethylenediamine) was used as molecular source for both Fe and F in Ar/O2 plasmas. The structure, morphology and chemical composition of the synthesized nanosystems were thoroughly analyzed by two-dimensional X-ray diffraction (XRD2), field emission-scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS) and transmission electron microscopy (TEM). A suitable choice of processing parameters enabled the selective formation of α-Fe2O3 nanomaterials, characterized by an homogeneous F doping, even at 100 °C. Interestingly, a simultaneous control of the system nanoscale organization and fluorine content could be achieved by varying the sole growth temperature. The tailored properties of the resulting materials can be favourably exploited for several technological applications, ranging from photocatalysis, to photoelectrochemical cells and gas sensing.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000326395800141 Publication Date 2013-10-03
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2046-2069; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 3.108 Times cited 23 Open Access
Notes Fwo Approved Most recent IF: 3.108; 2013 IF: 3.708
Call Number UA @ lucian @ c:irua:111091 Serial 1237
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Author Carraro, G.; Maccato, C.; Gasparotto, A.; Montini, T.; Turner, S.; Lebedev, O.I.; Gombac, V.; Adami, G.; Van Tendeloo, G.; Barreca, D.; Fornasiero, P.;
Title Enhanced hydrogen production by photoreforming of renewable oxygenates through nanostructured Fe2O3 polymorphs Type A1 Journal article
Year 2014 Publication Advanced functional materials Abbreviated Journal Adv Funct Mater
Volume 24 Issue 3 Pages 372-378
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Sunlight-driven hydrogen production via photoreforming of aqueous solutions containing renewable compounds is an attractive option for sustainable energy generation with reduced carbon footprint. Nevertheless, the absence of photocatalysts combining high efficiency and stability upon solar light activation has up to date strongly hindered the development of this technology. Herein, two scarcely investigated iron(III) oxide polymorphs, β- and ε-Fe2O3, possessing a remarkable activity in sunlight-activated H2 generation from aqueous solutions of renewable oxygenates (i.e., ethanol, glycerol, glucose) are reported. For β-Fe2O3 and ε-Fe2O3, H2 production rates up to 225 and 125 mmol h−1 m−2 are obtained, with significantly superior performances with respect to the commonly investigated α-Fe2O3.
Address
Corporate Author Thesis
Publisher Place of Publication Weinheim Editor
Language Wos 000332832500011 Publication Date 2013-10-08
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1616-301X; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 12.124 Times cited 95 Open Access
Notes Countatoms; Hercules; Fwo Approved Most recent IF: 12.124; 2014 IF: 11.805
Call Number UA @ lucian @ c:irua:113090 Serial 1051
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Author Morozov, V.A.; Lazoryak, B.I.; Shmurak, S.Z.; Kiselev, A.P.; Lebedev, O.I.; Gauquelin, N.; Verbeeck, J.; Hadermann, J.; Van Tendeloo, G.
Title Influence of the structure on the properties of NaxEuy(MoO4)z red phosphors Type A1 Journal article
Year 2014 Publication Chemistry of materials Abbreviated Journal Chem Mater
Volume 26 Issue 10 Pages 3238-3248
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Scheelite related compounds (A',A '')(n)[(B',B '')O-4](m) with B', B '' = W and/or Mo are promising new materials for red phosphors in pc-WLEDs (phosphor-converted white-light-emitting-diode) and solid-state lasers. Cation substitution in CaMoO4 of Ca2+ by the combination of Na+ and Eu3+, with the creation of A cation vacancies, has been investigated as a factor for controlling the scheelite-type structure and the luminescent properties. Na5Eu(MoO4)(4) and NaxEu(2-x)/33+square(2-x)/3MoO4 (0.138 <= x <= 0.5) phases with a scheelite-type structure were synthesized by the solid state method; their structural characteristics were investigated using transmission electron microscopy. Contrary to powder synchrotron X-ray diffraction before, the study by electron diffraction and high resolution transmission electron microscopy in this paper revealed that Na0.286Eu0.571MoO4 has a (3 + 2)D incommensurately modulated structure and that (3 + 2)D incommensurately modulated domains are present in Na0.200Eu0.600MoO4. It also confirmed the (3 + 1)D incommensurately modulated character of Na(0.138)Eu(0.621)Mo04. The luminescent properties of all phases under near-ultraviolet (n-UV) light have been investigated. The excitation spectra of these phosphors show the strongest absorption at about 395 nm, which matches well with the commercially available n-UV-emitting GaN-based LED chip. The emission spectra indicate an intense red emission due to the D-5(0) -> F-7(2) transition of Eu3+, with local minima in the intensity at Na0.286Eu0.571MoO4 and Na0.200Eu0.600MoO4 for similar to 613 nm and similar to 616 nm bands. The phosphor Na5Eu(MoO4)(4) shows the brightest red light emission among the phosphors in the Na2MoO4-Eu2/3MoO4 system and the maximum luminescence intensity of Na5Eu(MoO4)(4) (lambda(ex) = 395 nm) in the D-5(0) -> F-7(2) transition region is close to that of the commercially used red phosphor YVO4:Eu3+ (lambda(ex) = 326 nm). Electron energy loss spectroscopy measurements revealed the influence of the structure and Na/Eu cation distribution on the number and positions of bands in the UV-optical-infrared regions of the EELS spectrum.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000336637000028 Publication Date 2014-05-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0897-4756;1520-5002; ISBN Additional Links (up) UA library record; WoS full record; WoS citing articles
Impact Factor 9.466 Times cited 53 Open Access
Notes Fwo G039211n; Fwo G004413n; 278510 Vortex ECASJO_; Approved Most recent IF: 9.466; 2014 IF: 8.354
Call Number UA @ lucian @ c:irua:117765UA @ admin @ c:irua:117765 Serial 1652
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