“Magnetodielectric CuCr0.5V0.5O2 : an example of a magnetic and dielectric multiglass”. Singh K, Maignan A, Simon C, Kumar S, Martin C, Lebedev O, Turner S, Van Tendeloo G, Journal of physics : condensed matter 24, 226002 (2012). http://doi.org/10.1088/0953-8984/24/22/226002
Abstract: The complex dielectric susceptibility and spin glass properties of polycrystalline CuCr0.5V 0.5O2 delafossite have been investigated. Electron diffraction, high resolution electron microscopy and electron energy loss spectroscopy show that the Cr3+ and V 3+ magnetic cations are randomly distributed on the triangular network of CdI2-type layers. In contrast to CuCrO2, CuCr0.5V 0.5O2 exhibits two distinctive (magnetic and electric) glassy states evidenced by memory effects in electric and magnetic susceptibilities. A large magnetodielectric coupling is observed at low temperature.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.649
Times cited: 19
DOI: 10.1088/0953-8984/24/22/226002
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“Mechanism of preferential orientation in sputter deposited titanium nitride and yttria-stabilized zirconia layers”. Mahieu S, Ghekiere P, de Winter G, Heirwegh S, Depla D, de Gryse R, Lebedev OI, Van Tendeloo G, Journal of crystal growth 279, 100 (2005). http://doi.org/10.1016/j.jcrysgro.2005.02.014
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.751
Times cited: 41
DOI: 10.1016/j.jcrysgro.2005.02.014
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“The merging of silica-surfactant microspheres under hydrothermal conditions”. Liu S, Lebedev OI, Mertens M, Meynen V, Cool P, Van Tendeloo G, Vansant EF, Microporous and mesoporous materials: zeolites, clays, carbons and related materials 116, 141 (2008). http://doi.org/10.1016/j.micromeso.2008.03.034
Abstract: Post-synthesis hydrothermal treatments have been used to improve the quality of MCM-41 materials. In our latest work, merging of surfactant-containing silica microspheres during the hydrothermal treatments was observed. Mechanistic insights and the different stages that are involved in the merging process can be summarized as follows. First, the surfaces of the starting microspheres open up due to the dissolution of silica. Then the dissolved silica species provide mass source for the formation of particle necks connecting two neighboring microspheres. Gradually, surfaces of the starting microspheres are flattened to meet the needs of further growth of the necks. Finally, some chain-like highly-ordered mesoporous structures up to several micrometers are formed. The observed merging of the surfactant-containing microspheres is a re-assembling process, which is under the control of electrostatic force between the dissolved silica species and the surfactant cations. The occluded surfactant cations in the precursor spheres play important roles in the merging process.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA)
Impact Factor: 3.615
Times cited: 5
DOI: 10.1016/j.micromeso.2008.03.034
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“Mesoporous material formed by acidic hydrothermal assembly of silicalite-1 precursor nanoparticles in the absence of meso-templates”. Stevens WJJ, Meynen V, Bruijn E, Lebedev OI, Van Tendeloo G, Cool P, Vansant EF, Microporous and mesoporous materials: zeolites, clays, carbons and related materials 110, 77 (2008). http://doi.org/10.1016/j.micromeso.2007.09.007
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA)
Impact Factor: 3.615
Times cited: 21
DOI: 10.1016/j.micromeso.2007.09.007
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“Metal and composite nanocluster precipitate formation in silicon dioxide implanted with Sb+ ions”. Ignatova VA, Lebedev OI, Watjen U, van Vaeck L, van Landuyt J, Gijbels R, Adams F, Journal of applied physics 92, 4336 (2002). http://doi.org/10.1063/1.1508425
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.068
Times cited: 5
DOI: 10.1063/1.1508425
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“Metal to insulator transition in the n-type hollandite vanadate Pb1.6V8O16”. Maignan A, Lebedev OI, Van Tendeloo G, Martin C, Hebert S, Physical review : B : condensed matter and materials physics 82, 035122 (2010). http://doi.org/10.1103/PhysRevB.82.035122
Abstract: The transport and magnetic measurements of polycrystalline Pb1.6V8O16 hollandite reveal a concomitant metal to insulator and antiferromagnetic transition at TMI≈140 K. A clear localization is found below TMI, evidenced by a rapid increase in the absolute value of the negative Seebeck coefficient. The structural study by x-ray and transmission electron microscopy confirms the hollandite structure and shows that no structural transition occurs at TMI, ruling out a possible charge orbital ordering. The negative Seebeck coefficient observed from 50 K up to 900 K, with values reaching S=−38 μV K−1 at 900 K, is explained by the electron doping of ∼1.4e− in the V empty t2g orbitals responsible for the bad metal resistivity (ρ900 K∼2 mΩ cm). As this S value is close to that obtained by considering only the spin and orbital degeneracies, it is expected that |S| for such vanadates will not be sensitive at high temperature to the t2g band filling
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 10
DOI: 10.1103/PhysRevB.82.035122
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“Microstructure of YBa2Cu3O7-\delta Josephson junctions in relation to their properties”. Verbist K, Lebedev OI, Verhoeven MAJ, Winchern R, Rijnders AJHM, Blank DHA, Tafuri F, Bender H, Van Tendeloo G, Superconductor science and technology 11, 13 (1998). http://doi.org/10.1088/0953-2048/11/1/004
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.878
DOI: 10.1088/0953-2048/11/1/004
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“Misfit accommodation of epitaxial La1-xAxMnO3 (A=Ca, Sr) thin films”. Lebedev OI, Van Tendeloo G, Amelinckx S, International journal of inorganic materials 3, 1331 (2001). http://doi.org/10.1016/S1466-6049(01)00155-6
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 2
DOI: 10.1016/S1466-6049(01)00155-6
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“Mixed (Sr1-xCax)33Bi24Al48O141 fullerenoids: the defect structure analysed by (S)TEM techniques”. Lebedev OI, Bals S, Van Tendeloo G, Snoeck GE, Retoux R, Boudin S, Hervieu M, International journal of materials research 97, 978 (2006). http://doi.org/10.3139/146.101328
Abstract: (Sr1-xCax)(33)Bi-24,partial derivative Al48O141+3 partial derivative/2 fullerenoid solid solutions have been synthesized and the effect of partial substitution of Sr by Ca has been characterized by (scanning) transmission electron microscopy, applying different imaging methods. Most of the defects commonly observed in face centered cubic compounds, have also been observed in (Sr1-xCax)(33)Bi24-partial derivative Al48O141+3 partial derivative/2. Based on purely geometrical and topological models, structural presentations for the coherent twin boundaries and stacking faults have been constructed on the basis of complex spherical “Al84O210” units. The results are compared to defects observed in the crystallite fullerite C-60.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 0.681
Times cited: 1
DOI: 10.3139/146.101328
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“Mobility collapse in undoped and Si-doped GaN grown by LP-MOVPE”. Bougrioua Z, Farvacque J-L, Moerman I, Demeester P, Harris JJ, Lee K, Van Tendeloo G, Lebedev O, Trush EJ, Physica status solidi: B: basic research 216, 571 (1999). http://doi.org/10.1002/(SICI)1521-3951(199911)216:1<571::AID-PSSB571>3.0.CO;2-K
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.674
Times cited: 13
DOI: 10.1002/(SICI)1521-3951(199911)216:1<571::AID-PSSB571>3.0.CO;2-K
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“Multi-step loading of titania on mesoporous silica: influence of the morphology and the porosity on the catalytic degradation of aqueous pollutants and VOC's”. de Witte K, Meynen V, Mertens M, Lebedev OI, Van Tendeloo G, Sepúlveda-Escribano A, Rodríguez-Reinoso F, Vansant EF, Cool P, Applied catalysis : B : environmental 84, 125 (2008). http://doi.org/10.1016/j.apcatb.2008.03.015
Abstract: Titania nanoparticles have been deposited on inert porous silica supports with high specific surface area. These materials have potential applications in paint and textile industry as the titania particles selectively deposited on the inner surface of the silica supports act as a photocatalyst. The inert external surface is necessary to avoid photodegradation of the textile material or the paint components. The photocatalytic activity of the catalysts has been evaluated with two catalytic setups. One setup in aqueous phase, for the degradation of dyes such as rhodamine-6G, is commonly used. The second setup is a continuous flow gaseous phase setup which was used for the mineralization of ethanol as a representative volatile organic compound (VOC). The influence of the porosity and the morphology of the silica supports on the photocatalytic activity are discussed.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA)
Impact Factor: 9.446
Times cited: 24
DOI: 10.1016/j.apcatb.2008.03.015
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“Nanodiamond photoemitters based on strong narrow-band luminescence from silicon-vacancy defects”. Vlasov II, Barnard AS, Ralchenko VG, Lebedev OI, Kanzyuba MV, Saveliev AV, Konov VI, Goovaerts E, Advanced materials 21, 808 (2009). http://doi.org/10.1002/adma.200802160
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Nanostructured and organic optical and electronic materials (NANOrOPT)
Impact Factor: 19.791
Times cited: 98
DOI: 10.1002/adma.200802160
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“Nanoscale ordering in oxygen deficient quintuple perovskite Sm2-\epsilonBa3+\epsilonFe5O15-\delta : implication for magnetism and oxygen stoichiometry”. Volkova NE, Lebedev OI, Gavrilova LY, Turner S, Gauquelin N, Seikh MM, Caignaert V, Cherepanov VA, Raveau B, Van Tendeloo G, Chemistry of materials 26, 6303 (2014). http://doi.org/10.1021/cm503276p
Abstract: The investigation of the system SmBaFe-O in air has allowed an oxygen deficient perovskite Sm2-epsilon Ba3+epsilon Fe5O15-delta (delta = 0.75, epsilon = 0.125) to be synthesized. In contrast to the XRPD pattern which gives a cubic symmetry (a(p) = 3.934 angstrom), the combined HREM/EELS study shows that this phase is nanoscale ordered with a quintuple tetragonal cell, a(p) X a(p) X 5(ap). The nanodomains exhibit a unique stacking sequence of the A-site cationic layers along the crystallographic c-axis, namely SmBaBa/SmBa/SmBaSm, and are chemically twinned in the three crystallographic directions. The nanoscale ordering of this perovskite explains its peculiar magnetic properties on the basis of antiferromagnetic interactions with spin blockade at the boundary between the nanodomains. The variation of electrical conductivity and oxygen content of this oxide versus temperature suggest potential SOFC applications. They may be related to the particular distribution of oxygen vacancies in the lattice and to the 3d(5)(L) under bar configuration of iron.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 16
DOI: 10.1021/cm503276p
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“Negative magnetoresistance in a V3+/V4+ mixed valent vanadate”. Maignan A, Lebedev OI, Van Tendeloo G, Martin C, Hébert S, Applied physics letters 96, 232502 (2010). http://doi.org/10.1063/1.3446892
Abstract: The magnetotransport and magnetic properties of the PbV6O11 vanadate, crystallizing in the P63mc space group, reveal the existence of a negative magnetoresistance related to its ferromagnetic state (TC ∼ 90 K). The maximum effect is observed at 20 K reaching −30% in 9 T. The structural study of this ceramic reveals a V/Pb ratio smaller than expected from the formula. This is explained by the presence of numerous stacking faults observed by high resolution transmission electron microscopy. The existence of these planar defects acting as resistive barriers along the c axis could be responsible for tunneling magnetoresistance.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.411
DOI: 10.1063/1.3446892
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“New insights in the formation of combined zeolitic/mesoporous materials by using a one-pot templating synthesis”. Vernimmen J, Meynen V, Herregods SJF, Mertens M, Lebedev OI, Van Tendeloo G, Cool P, European journal of inorganic chemistry , 4234 (2011). http://doi.org/10.1002/ejic.201100268
Abstract: Zeolitic growth is often absent or occurs in separate phases when synthetic strategies based on the combination of zeolite templates and mesopore templating agents are applied. In this work, zeolitic growth and mesopore formation have been investigated at different temperatures by applying a one-pot templating approach, based on a TS-1 zeolite synthesis whereby part of the microtemplate (tetrapropylammonium hydroxide, TPAOH) is replaced by a mesotemplate (hexadecyltrimethylammonium bromide, CTMABr). Moreover, the synthesis duration and the molar ratio of the microtemplate/mesotemplate have also been studied. The different syntheses clearly show the inherent competitive mechanism between zeolitic growth and mesopore formation. These insights have led to the conclusion that by following a one-pot templating strategy with standard, nonexotic commercial templates, i.e. CTMABr and TPAOH, it is not possible to develop a true hierarchical mesoporous zeolite, meaning a mesoporous siliceous material with highly crystalline zeolitic walls. The resultant materials are instead combined zeolitic/mesoporous composite structures with, however, highly tuneable and controllable porosity characteristics.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA)
Impact Factor: 2.444
Times cited: 7
DOI: 10.1002/ejic.201100268
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“A new iron oxophosphate SrFe3(PO4)3O with chain-like structure”. Morozov VA, Pokholok KV, Lazoryak BI, Malakho AP, Lachgar A, Lebedev OI, Van Tendeloo G, Journal of solid state chemistry 170, 411 (2003). http://doi.org/10.1016/S0022-4596(02)00133-0
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.299
Times cited: 12
DOI: 10.1016/S0022-4596(02)00133-0
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“New molybdenum oxides Ag4M2Zr(MoO4)6 (M=Mg, Mn, Co, Zn) with a channel-like structure”. Khobrakova ET, Morozov VA, Khasanov SS, Tsyrenova GD, Khaikina EG, Lebedev OI, Van Tendeloo G, Lazoryak BI, Solid state sciences 7, 1397 (2005). http://doi.org/10.1016/j.solidstatesciences.2005.08.010
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.811
Times cited: 9
DOI: 10.1016/j.solidstatesciences.2005.08.010
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“New nano-architectures of mesoporous silica spheres analyzed by advanced electron microscopy”. Lebedev OI, Turner S, Liu S, Cool P, Van Tendeloo G, Nanoscale 4, 1722 (2012). http://doi.org/10.1039/c2nr11715k
Abstract: Using template-containing silica microspheres as a precursor, novel ordered mesoporous silica nanoparticles with a narrow pore size distribution and high crystallinity have been synthesized by various hydrothermal merging processes. Several architectures like chains, dumbbells, triangles, squares and flowers have been discovered. The linking mechanisms of these interacting silica spheres leading to the formation of ordered nano-structures are studied by HRTEM, HAADF-STEM and electron tomography and a plausible model is presented for several merging processes.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA)
Impact Factor: 7.367
Times cited: 5
DOI: 10.1039/c2nr11715k
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“A new structure type of the ternary sulfide Eu1.3Nb1.9S5”. Khasanova NR, Van Tendeloo G, Lebedev OI, Amelinckx S, Grippa AY, Abakumov AM, Istomin SY, D'yachenko OG, Antipov EV, Journal of solid state chemistry 164, 345 (2002). http://doi.org/10.1006/jssc.2001.9501
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.299
Times cited: 2
DOI: 10.1006/jssc.2001.9501
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“Nickel/carbon composite materials based on expanded graphite”. Afanasov IM, Lebedev OI, Kolozhvary BA, Smirnov AV, Van Tendeloo G, New carbon materials 26, 335 (2011). http://doi.org/10.1016/S1872-5805(11)60085-1
Abstract: Monolithic nickel/carbon (Ni/C) composites were prepared from coal tar pitch-impregnated compressed expanded graphite pre-decorated with NiO particles (EGNiO) by pyrolysis at 550 °C and subsequent steam activation at 800 °C. The microstructural arrangement of the Ni-comprising nanoparticles in the composites was investigated using transmission electron microscopy. The specific surface area and porosity of the composites were analyzed by nitrogen adsorption. The catalytic activity of the composites was compared with the material obtained by the conventional H2 treatment of EGNiO using hydrocracking of 2,2,3-trimethylpentane as a model reaction.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 7
DOI: 10.1016/S1872-5805(11)60085-1
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“Nitrogen and luminescent nitrogen-vacancy defects in detonation nanodiamond”. Vlasov II, Shenderova O, Turner S, Lebedev OI, Basov AA, Sildos I, Rähn M, Shiryaev AA, Van Tendeloo G, Small 6, 687 (2010). http://doi.org/10.1002/smll.200901587
Abstract: An efficient method to investigate the microstructure and spatial distribution of nitrogen and nitrogen-vacancy (N-V) defects in detonation nanodiamond (DND) with primary particle sizes ranging from approximately 3 to 50 nm is presented. Detailed analysis reveals atomic nitrogen concentrations as high as 3 at% in 50% of diamond primary particles with sizes smaller than 6 nm. A non-uniform distribution of nitrogen within larger primary DND particles is also presented, indicating a preference for location within the defective central part or at twin boundaries. A photoluminescence (PL) spectrum with well-pronounced zero-phonon lines related to the N-V centers is demonstrated for the first time for electron-irradiated and annealed DND particles at continuous laser excitation. Combined Raman and PL analysis of DND crystallites dispersed on a Si substrate leads to the conclusion that the observed N-V luminescence originates from primary particles with sizes exceeding 30 nm. These findings demonstrate that by manipulation of the size/nitrogen content in DND there are prospects for mass production of nanodiamond photoemitters based on bright and stable luminescence from nitrogen-related defects.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 8.643
Times cited: 84
DOI: 10.1002/smll.200901587
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“Novel MoVSbOx-type catalysts for selective isobutane oxidation”. Paul JS, Groothaert MH, Kirschhock CEA, Lebedev OI, Jacobs PA, Maier WF, Catalysis today
T2 –, 7th European Workshop Meeting on Selective Oxidation, AUG 31-SEP 04, 2003, Innsbruck, AUSTRIA 91-2, 265 (2004). http://doi.org/10.1016/j.cattod.2004.03.041
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.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.636
Times cited: 12
DOI: 10.1016/j.cattod.2004.03.041
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“Observation of Sb203 nanocrystals in SiO2 after Sb ion implantation”. Ignatova VA, Lebedev OI, Wätjen U, van Vaeck L, van Landuyt J, Gijbels R, Adams F, Microchimica acta 139, 77 (2002). http://doi.org/10.1007/s006040200043
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.58
Times cited: 3
DOI: 10.1007/s006040200043
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“Off-stoichiometry effects on the crystalline and defect structure of hexagonal manganite REMnO3 films (RE = Y, Er, Dy)”. Gélard J, Jehanathan N, Roussel H, Gariglio S, Lebedev OI, Van Tendeloo G, Dubourdieu C, Chemistry of materials 23, 1232 (2011). http://doi.org/10.1021/cm1029358
Abstract: The crystalline and defect structure of epitaxial hexagonal RExMnyO3 (RE = Er, Dy) films with varying cationic composition was investigated by X-ray diffraction and transmission electron microscopy. The films are composed of a strained layer at the interface with the substrate and of a relaxed layer on top of it. The critical thickness is of 10 to 25 nm. For Mn-rich films (or RE deficient), an off-stoichiometric composition maintaining the hexagonal LuMnO3-type structure is stabilized over a large range of the RE/Mn ratio (0.72−1.00), with no Mn-rich secondary phases observed. A linear dependence of the out-of-plane lattice parameter with RE/Mn is observed in this range. Out-of-phase boundary (OPB) extended defects are observed in all films and exhibit a local change in stoichiometry. Such a large solubility limit in the RE deficient region points toward the formation of vacancies on the RE site (RExMnO3−δ, with 0.72 ≤ x < 1), a phenomenon that is encountered in perovskite manganites such as LaxMnO3−δ (x < 1) and that may strongly impact the physical properties of hexagonal manganites.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 17
DOI: 10.1021/cm1029358
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“One-step synthesis of shelled PbS nanoparticles in a layered double hydroxide matrix”. Lukashin AV, Eliseev AA, Zhuravleva NG, Vertegel AA, Tretyakov YD, Lebedev OI, Van Tendeloo G, Mendeleev communications , 174 (2004). http://doi.org/10.1070/MC2004v014n04ABEH001973
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.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.741
Times cited: 9
DOI: 10.1070/MC2004v014n04ABEH001973
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“Optical spectroscopy of oxygen precipitates in heavily doped p-type silicon”. Simoen E, Loo R, Claeys C, de Gryse O, Clauws P, van Landuyt J, Lebedev O, Journal of physics : condensed matter
T2 –, Conference on Extended Defects in Semiconductors (EDS 2002), JUN 01-06, 2002, BOLOGNA, ITALY 14, 13185 (2002). http://doi.org/10.1088/0953-8984/14/48/367
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.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.649
Times cited: 3
DOI: 10.1088/0953-8984/14/48/367
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“Ordering of tetrahedral chains in the Sr2MnGaO5 brownmillerite”. Abakumov AM, Alekseeva AM, Rozova MG, Antipov EV, Lebedev OI, Van Tendeloo G, Journal of solid state chemistry 174, 319 (2003). http://doi.org/10.1016/S0022-4596(03)00226-3
Abstract: Tetrahedral chain ordering in the Sr2MnGaO5 structure is studied using electron diffraction (ED) and high-resolution electron microscopy. The ED patterns show the presence of satellite reflections, which indicate a commensurately modulated structure with a = 5.4056(8) Angstrom b 16.171(3) Angstrom, c = 5.5592(7) Angstrom, q – 1/2c*, superspace group Immma(00gamma,)s00. The Superstructure arises due to ordering of the two types of symmetry related tetrahedral chains (L and R) according to a ... LRLR ... sequence, where L and R chains alternate along the c-axis within the same (GaO) layer. Numerous defects at different structural levels were observed, comprising interleaving L and R chains, violation of the ... LRLR ... chain sequence within one layer, different stacking modes of the ... LRLR ... ordered layers with subsequent alternation of blocks of different width along the h-axis of the brownmillerite subcell and island fragmentation of the modulated superstructure. By in situ heating ED experiments it is found that the long-range ordering of the tetrahedral chains is stable tip to 665degreesC and is completely suppressed at 905degreesC. (C) 2003 Elsevier Inc. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.299
Times cited: 34
DOI: 10.1016/S0022-4596(03)00226-3
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“Origin of different deactivation of Pd/SnO2 and Pd/GeO2 catalysts in methanol dehydrogenation and reforming: a comparative study”. Lorenz H, Zhao Q, Turner S, Lebedev OI, Van Tendeloo G, Kloetzer B, Rameshan C, Pfaller K, Applied catalysis : A : general 381, 242 (2010). http://doi.org/10.1016/j.apcata.2010.04.015
Abstract: Pd particles supported on SnO2 and GeO2 have been structurally investigated by X-ray diffraction, (High-Resolution) transmission and scanning electron microscopy after different reductive treatments to monitor the eventual formation of bimetallic phases and catalytically tested in methanol dehydrogenation/ reforming. For both oxides this included a thin film sample with well-defined Pd particles and a powder catalyst prepared by incipient wetness impregnation. The hexagonal and the tetragonal polymorph were studied for powder GeO2. Pd2Ge formation was observed on all GeO2-supported catalysts, strongly depending on the specific sample used. Reduction of the thin film at 573K resulted in full transformation into the bimetallic state. The partial solubility of hexagonal GeO2 in water and its thermal structural instability yielded Pd2Ge formation at 473 K, at the cost of a structurally inhomogeneous support and Ge metal formation at higher reduction temperatures. Pd on tetragonal GeO2 entered a state of strong metalsupport interaction after reduction at 573673 K, resulting in coalescing Pd2Ge particles on a sintered and re-crystallized support, apparently partially covering the bimetallic particles and decreasing the catalytic activity. Pd2Ge on amorphous thin film and hexagonal GeO2 converted methanol primarily via dehydrogenation to CO and H2. At 573 K, formation of Pd2Sn and also PdSn occurred on the Pd/SnO2 thin film. Pd3Sn2 (and to some extent Pd2Sn) were predominantly obtained on the respective powder catalyst. Strong deactivation with increasing reduction temperature was observed, likely not based on the classical strong metalsupport interaction effect, but rather on a combination of missing active structural ensembles on Sn-enriched bimetallic phases and the formation of metallic -Sn. Correlations to Pd and its bimetallics supported on ZnO, Ga2O3 and In2O3 were also discussed.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.339
Times cited: 14
DOI: 10.1016/j.apcata.2010.04.015
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“Oxide phase determination in silicon using infrared spectroscopy and transmission electron microscopy techniques”. Gryse OD, Clauws P, van Landuyt J, Lebedev O, Claeys C, Simoen E, Vanhellemont J, Journal of applied physics 91, 2493 (2002). http://doi.org/10.1063/1.1429800
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.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.068
Times cited: 27
DOI: 10.1063/1.1429800
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“Oxygen and fluorine doping in Sr2MnGaO5 brownmillerite”. Antipov EV, Abakumov AM, Alekseeva AM, Rozova MG, Hadermann J, Lebedev OI, Van Tendeloo G, Physica status solidi: A: applied research 201, 1403 (2004). http://doi.org/10.1002/pssa.200304428
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 9
DOI: 10.1002/pssa.200304428
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