“Antiferroelectric phase transition in Sr9In(PO4)7”. Stefanovich SY, Belik AA, Azuma M, Takano M, Baryshnikova OV, Morozov VA, Lazoryak BI, Lebedev OI, Van Tendeloo G, Physical review : B : condensed matter and materials physics 70, 172103 (2004). http://doi.org/10.1103/PhysRevB.70.172103
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 17
DOI: 10.1103/PhysRevB.70.172103
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“Ga segregation in DyBa2Cu3O7-\delta/PrBa2Cu3-xGaxO7-\delta/DyBa2Cu3O7-\delta ramp-type Josephson junctions”. Verbist K, Lebedev OI, Van Tendeloo G, Verhoeven MAJ, Rijnders AJHM, Blank DHA, Rogalia H, Applied physics letters 70, 1167 (1997)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.411
Times cited: 8
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“Proximity induced metal-insulator transition in YBa2Cu3O7/La2/3Ca1/3MnO3 superlattices”. Holden T, Habermeier H-U, Cristiani G, Golnik A, Boris A, Pimenov A, Humlicek J, Lebedev OI, Van Tendeloo G, Keimer B, Bernhard C, Physical review : B : condensed matter and materials physics 69, 064505 (2004). http://doi.org/10.1103/PhysRevB.69.064505
Abstract: The far-infrared dielectric response of superlattices (SL) composed of superconducting YBa2Cu3O7 (YBCO) and ferromagnetic La0.67Ca0.33MnO3 (LCMO) has been investigated by ellipsometry. A drastic decrease of the free-carrier response is observed which involves an unusually large length scale of d(crit)approximate to20 nm in YBCO and d(crit)approximate to10 nm in LCMO. A corresponding suppression of metallicity is not observed in SL's where LCMO is replaced by the paramagnetic metal LaNiO3. Our data suggest that either a long-range charge transfer from the YBCO to the LCMO layers or alternatively a strong coupling of the charge carriers to the different and competitive kind of magnetic correlations in the LCMO and YBCO layers is at the heart of the observed metal-insulator transition. The low free-carrier response observed in the far-infrared dielectric response of the magnetic superconductor RuSr2GdCu2O8 is possibly related to this effect.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 101
DOI: 10.1103/PhysRevB.69.064505
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“Dislocations in diamond : dissociation into partials and their glide motion”. Blumenau AT, Jones R, Frauenheim T, Willems B, Lebedev OI, Van Tendeloo G, Fisher D, Martineau PM, Physical review : B : condensed matter and materials physics 68, 014115 (2003). http://doi.org/10.1103/PhysRevB.68.014115
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.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 39
DOI: 10.1103/PhysRevB.68.014115
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“Structure and microstructure of colossal magnetoresistant materials”. Van Tendeloo G, Lebedev OI, Hervieu M, Raveau B, Reports on progress in physics 67, 1315 (2004). http://doi.org/10.1088/0034-4885/67/8/R01
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 14.311
Times cited: 79
DOI: 10.1088/0034-4885/67/8/R01
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“Structural phase transitions and stress accommodation in (La0.67Ca0.33MnO3)1.x:(MgO)x composite films”. Lebedev OI, Verbeeck J, Van Tendeloo G, Shapoval O, Belenchuk A, Moshnyaga V, Damaschke B, Samwer K, Physical review : B : condensed matter and materials physics 66, 104421 (2002). http://doi.org/10.1103/PhysRevB.66.104421
Abstract: Composite (La0.67Ca0.33MnO3)(1-x):(MgO)(x) films were prepared by metalorganic aerosol deposition on a (100)MgO substrate for different concentrations of the (MgO) phase (0less than or equal toxless than or equal to0.8). At xapproximate to0.3 a percolation threshold in conductivity is reached, at which an infinite insulating MgO cluster forms around the La0.67Ca0.33MnO3 grains. This yields a drastic increase of the electrical resistance for films with x>0.3. The film structure is characterized by x-ray diffraction and transmission electron microscopy. The local structure of the La0.67Ca0.33MnO3 within the film depends on the MgO concentration which grows epitaxially along the domain boundaries. A different structural phase transition from the orthorhombic Pnma structure to an unusual rhombohedral R (3) over barc structure at the percolation threshold xapproximate to0.3 is found for La0.67Ca0.33MnO3. A three-dimensional stress accommodation in thick films through a phase transition is suggested.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 48
DOI: 10.1103/PhysRevB.66.104421
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“Superconductivity and microstructure of YSr2Cu3O6.875”. Lebedev OI, Van Tendeloo G, Licci F, Gilioli E, Gauzzi A, Prodi A, Marezio M, Physical review : B : condensed matter and materials physics 66, 132510 (2002). http://doi.org/10.1103/PhysRevB.66.132510
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 9
DOI: 10.1103/PhysRevB.66.132510
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“SrTiO3(100)/(LaMnO3)m(SrMnO3)n layered heterostructures: a combined EELS and TEM study”. Verbeeck J, Lebedev OI, Van Tendeloo G, Mercey B, Physical review : B : condensed matter and materials physics 66, 184426 (2002). http://doi.org/10.1103/PhysRevB.66.184426
Abstract: Epitaxially grown heterostructures consisting of alternating layers of LaMnO(3) (LMO, 9 or 15 unit cells) and SrMnO(3) (SMO, 4 or 6 unit cells) on a SrTiO(3)(100) (STO(100)) substrate have been studied by a combination of high resolution transmission electron microscopy (HRTEM), electron diffraction, quantitative electron energy loss spectroscopy (EELS) with model fitting, energy filtered TEM (EFTEM) and imaging spectroscopy on an atomic scale. The combination of these techniques is necessary for the structural, chemical, and electronic characterization of these heterostructures. A model is proposed containing chemically and structurally sharp interfaces. The SrMnO(3) layers are stabilized in a Pm3m structure between two LMO layers. Tensile stress causes oxygen deficiency in the SMO layers increasing the number of 3d electrons on the Mn sites to resemble the Mn(3+) sites in LMO. The energy loss near edge structure (ELNES) of O and Mn is compared for both LMO and SMO layers and shows that the Mn-O bonds have a partially covalent character. The absence of a strong valency effect in the Mn ELNES is due to the oxygen vacancies in SMO.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 32
DOI: 10.1103/PhysRevB.66.184426
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“Phase transition and magnetic anisotropy of (La,Sr)MnO3 thin films”. Wang Z-H, Kronmüller H, Lebedev OI, Gross GM, Razavi FS, Habermeier HU, Shen BG, Physical review : B : condensed matter and materials physics 65, 054411 (2002). http://doi.org/10.1103/PhysRevB.65.054411
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.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 23
DOI: 10.1103/PhysRevB.65.054411
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“In situ HREM irradiation study of point-defect clustering in MBE-grown strained Si1-xGex/(001)Si structures”. Fedina L, Lebedev OI, Van Tendeloo G, van Landuyt J, Mironov OA, Parker EHC, Physical review : B : condensed matter and materials physics 61, 10336 (2000). http://doi.org/10.1103/PhysRevB.61.10336
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.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 27
DOI: 10.1103/PhysRevB.61.10336
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“Structural and magnetic properties of the colossal magnetoresistance perovskite La0.85Ca0.15MnO3”. Lobanov MV, Balagurov AM, Pomjakushin VJ, Fischer P, Gutmann M, Abakumov AM, D'yachenko OG, Antipov EV, Lebedev OI, Van Tendeloo G, Physical review : B : condensed matter and materials physics 61, 8941 (2000). http://doi.org/10.1103/PhysRevB.61.8941
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 47
DOI: 10.1103/PhysRevB.61.8941
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“Structure and microstructure of La1-xCaxMnO3- thin films prepared by pulsed layer deposition”. Lebedev OI, Van Tendeloo G, Amelinckx S, Leibold B, Habermeier H-U, Physical review : B : condensed matter and materials physics 58, 8065 (1998). http://doi.org/10.1103/PhysRevB.58.8065
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 131
DOI: 10.1103/PhysRevB.58.8065
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“The phase transition and crystal structures of Ba3RM2O7.5 complex oxides (R=rare-earth elements, M = Al,Ga)”. Abakumov AM, Shpanchenko RV, Lebedev OI, Van Tendeloo G, Amelinckx S, Antipov EV, Acta crystallographica: section A: foundations of crystallography 55, 828 (1999). http://doi.org/10.1107/S0108767399002068
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 5.725
Times cited: 7
DOI: 10.1107/S0108767399002068
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“Unprecedented shape selectivity in hydrogenation of triacylglycerol molecules with Pt/ZSM-5 zeolite”. Philippaerts A, Paulussen S, Breesch A, Turner S, Lebedev OI, Van Tendeloo G, Sels B, Jacobs P, Angewandte Chemie: international edition in English 50, 3947 (2011). http://doi.org/10.1002/anie.201007513
Abstract: Well tuned: ZSM-5 with platinum nanoparticles preferably hydrogenates trans fatty acids over cis isomers in model triacylglycerols for geometric reasons. The central fatty acid chain reacts faster, pointing to pore mouth adsorption in a tuning fork conformation (see picture). This conformation induces stepwise hydrogenation, resulting in fast removal of the unstable central triene, while formation of saturated chains is limited.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 11.994
Times cited: 31
DOI: 10.1002/anie.201007513
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“Expanded graphite as a support for Ni/carbon composites”. Afanasov IM, Shornikova ON, Avdeev VV, Lebedev OI, Van Tendeloo G, Matveev AT, Carbon 47, 513 (2009). http://doi.org/10.1016/j.carbon.2008.10.034
Abstract: Expanded graphite decorated with nickel oxide particles (EGNiO) has been synthesized through electrochemical oxidation of natural graphite in an aqueous nickel nitrate solution followed by a heat treatment. EGNiO was used to prepare nickel/carbon composites using two techniques: (a) hydrogen reduction of nickel oxide particles loaded on the expanded graphite surface and (b) pyrolysis of coal tar pitch-impregnated EGNiO blocks. The EGNiO as well as the nickel/carbon composites have been characterized by X-ray diffraction, scanning and transmission electron microscopy, energy dispersive X-ray spectroscopy and selected area electron diffraction.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 6.337
Times cited: 45
DOI: 10.1016/j.carbon.2008.10.034
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“HREM study of ion implantation in 6H-SiC at high temperatures”. Lebedev OI, Van Tendeloo G, Suvorova AA, Usov IO, Suvorov AV, Journal of electron microscopy 46, 271 (1997)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 0.9
Times cited: 7
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“Synthesis and structure of fluorinated RBa2Cu2O6+. (R=Dy, Ho and Tm) phases”. Oleynikov PN, Shpanchenko RV, Rozova MG, Abakumov AM, Antipov EV, Hadermann J, Lebedev OI, Van Tendeloo G, Russian journal of inorganic chemistry 46, 153 (2001)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 0.787
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“Sn19.3Cu4.7As22I8: a new clathrate-I compound with transition-metal atoms in the cationic framework”. Kovnir KA, Sobolev AV, Presniakov IA, Lebedev OI, Van Tendeloo G, Schnelle W, Grin Y, Shevelkov AV, Inorganic chemistry 44, 8786 (2005). http://doi.org/10.1021/ic051160k
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.857
Times cited: 38
DOI: 10.1021/ic051160k
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“Anion ordering and defect structure in Ruddlesden-Popper strontium niobium oxynitrides”. Tobías G, Beltrán-Porter D, Lebedev OI, Van Tendeloo G, Rodríguez-Carvajal J, Fuertes A, Inorganic chemistry 43, 8010 (2004). http://doi.org/10.1021/ic049236k
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.857
Times cited: 31
DOI: 10.1021/ic049236k
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“Crystal structures of superconducting sodium intercalates of hafnium nitride chloride”. Oró-Solé, J, Frontera C, Beltrán-Porter D, Lebedev OI, Van Tendeloo G, Fuertes A, Materials research bulletin 41, 934 (2006). http://doi.org/10.1016/j.materresbull.2006.03.018
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.446
Times cited: 8
DOI: 10.1016/j.materresbull.2006.03.018
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“Plasma-assisted synthesis of Ag/ZnO nanocomposites : first example of photo-induced H2 production and sensing”. Simon Q, Barreca D, Bekermann D, Gasparotto A, Maccato C, Comini E, Gombac V, Fornasiero P, Lebedev OI, Turner S, Devi A, Fischer RA, Van Tendeloo G, International journal of hydrogen energy 36, 15527 (2011). http://doi.org/10.1016/j.ijhydene.2011.09.045
Abstract: Ag/ZnO nanocomposites were developed by a plasma-assisted approach. The adopted strategy exploits the advantages of Plasma Enhanced-Chemical Vapor Deposition (PE-CVD) for the growth of columnar ZnO arrays on Si(100) and Al2O3 substrates, in synergy with the infiltration power of the Radio Frequency (RF)-sputtering technique for the subsequent dispersion of different amounts of Ag nanoparticles (NPs). The resulting composites, both as-prepared and after annealing in air, were thoroughly characterized with particular attention on their morphological organization, structure and composition. For the first time, the above systems have been used as catalysts in the production of hydrogen by photo-reforming of alcoholic solutions, yielding a stable H2 evolution even by the sole use of simulated solar radiation. In addition, Ag/ZnO nanocomposites presented an excellent response in the gas-phase detection of H2, opening attractive perspectives for advanced technological applications.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.582
Times cited: 62
DOI: 10.1016/j.ijhydene.2011.09.045
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“Rational synthesis of a nanocrystalline calcium phosphate cement exhibiting rapid conversion to hydroxyapatite”. Neira IS, Kolen'ko YV, Lebedev OI, Van Tendeloo G, Gupta HS, Matsushita N, Yoshimura M, Guitian F, Materials science and engineering: part C: biomimetic materials 29, 2124 (2009). http://doi.org/10.1016/j.msec.2009.04.011
Abstract: The rational synthesis, comprehensive characterization, and mechanical and micromechanical properties of a calcium phosphate cement are presented. Hydroxyapatite cement biomaterial was synthesized from reactive sub-micrometer-sized dicalcium phosphate dihydrate and tetracalcium phosphate via a dissolution-precipitation reaction using water as the liquid phase. As a result nanostructured, Ca-deficient and carbonated B-type hydroxyapatite is formed. The cement shows good processibility, sets in 22 ± 2 min and entirely transforms to the end product after 6 h of setting reaction, one of the highest conversion rates among previously reported for calcium phosphate cements based on dicalcium and tetracalcium phosphates. The combination of all elucidated physical-chemical traits leads to an essential bioactivity and biocompatibility of the cement, as revealed by in vitro acellular simulated body fluid and cell culture studies. The compressive strength of the produced cement biomaterial was established to be 25 ± 3 MPa. Furthermore, nanoindentation tests were performed directly on the cement to probe its local elasticity and plasticity at sub-micrometer/micrometer level. The measured elastic modulus and hardness were established to be Es = 23 ± 3.5 and H = 0.7 ± 0.2 GPa, respectively. These values are in close agreement with those reported in literature for trabecular and cortical bones, reflecting good elastic and plastic coherence between synthesized cement biomaterial and human bones.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.164
Times cited: 18
DOI: 10.1016/j.msec.2009.04.011
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“Exceptional layered ordering of cobalt and iron in perovskites”. Lebedev OI, Turner S, Caignaert V, Cherepanov VA, Raveau B, Chemistry of materials 28, 2907 (2016). http://doi.org/10.1021/acs.chemmater.6b01046
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 4
DOI: 10.1021/acs.chemmater.6b01046
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“Immersion calorimetry as a tool to evaluate the catalytic performance of titanosilicate materials in the epoxidation of cyclohexene”. Vernimmen J, Guidotti M, Silvestre-Albero J, Jardim EO, Mertens M, Lebedev OI, Van Tendeloo G, Psaro R, Rodríguez-Reinoso F, Meynen V, Cool P, Langmuir: the ACS journal of surfaces and colloids 27, 3618 (2011). http://doi.org/10.1021/la104808v
Abstract: Different types of titanosilicates are synthesized, structurally characterized, and subsequently catalytically tested in the liquid-phase epoxidation of cyclohexene. The performance of three types of combined zeolitic/mesoporous materials is compared with that of widely studied Ti-grafted-MCM-41 molecular sieve and the TS-1 microporous titanosilicate. The catalytic test results are correlated with the structural characteristics of the different catalysts. Moreover, for the first time, immersion calorimetry with the same substrate molecule as in the catalytic test reaction is applied as an extra means to interpret the catalytic results. A good correlation between catalytic performance and immersion calorimetry results is found. This work points out that the combination of catalytic testing and immersion calorimetry can lead to important insights into the influence of the materials structural characteristics on catalysis. Moreover, the potential of using immersion calorimetry as a screening tool for catalysts in epoxidation reactions is shown.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA)
Impact Factor: 3.833
Times cited: 19
DOI: 10.1021/la104808v
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“Tailored vapor-phase growth of CuxO-TiO2(x=1,2) nanomaterials decorated with Au particles”. Barreca D, Carraro G, Gasparotto A, Maccato C, Lebedev OI, Parfenova A, Turner S, Tondello E, Van Tendeloo G, Langmuir: the ACS journal of surfaces and colloids 27, 6409 (2011). http://doi.org/10.1021/la200698t
Abstract: We report on the fabrication of CuxOTiO2 (x = 1, 2) nanomaterials by an unprecedented vapor-phase approach. The adopted strategy involves the growth of porous CuxO matrices by means of chemical vapor deposition (CVD), followed by the controlled dispersion of TiO2 nanoparticles. The syntheses are performed on Si(100) substrates at temperatures of 400550 °C under wet oxygen atmospheres, adopting Cu(hfa)2·TMEDA (hfa =1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA = N,N,N′,N′-tetramethylethylenediamine) and Ti(O-iPr)2(dpm)2 (O-iPr = isopropoxy; dpm = 2,2,6,6-tetramethyl-3,5-heptanedionate) as copper and titanium precursors, respectively. Subsequently, finely dispersed gold nanoparticles are introduced in the as-prepared systems via radio frequency (RF)-sputtering under mild conditions. The synthesis process results in the formation of systems with chemical composition and nano-organization strongly dependent on the nature of the initial CuxO matrix and on the deposited TiO2 amount. The decoration with low-size gold clusters paves the way to the engineering of hierarchically organized nanomaterials.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.833
Times cited: 36
DOI: 10.1021/la200698t
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“Influence of the structure on the properties of NaxEuy(MoO4)z red phosphors”. Morozov VA, Lazoryak BI, Shmurak SZ, Kiselev AP, Lebedev OI, Gauquelin N, Verbeeck J, Hadermann J, Van Tendeloo G, Chemistry of materials 26, 3238 (2014). http://doi.org/10.1021/cm500966g
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.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 53
DOI: 10.1021/cm500966g
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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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“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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“Size-Induced Switching of Nanowire Growth Direction: a New Approach Toward Kinked Nanostructures”. Shen Y, Lebedev OI, Turner S, Van Tendeloo G, Song X, Yu X, Wang Q, Chen H, Dayeh SA, Wu T, Advanced functional materials 26, 3687 (2016). http://doi.org/10.1002/ADFM.201600142
Abstract: Exploring self-assembled nanostructures with controllable architectures has been a central theme in nanoscience and nanotechnology because of the tantalizing perspective of directly integrating such bottom-up nanostructures into functional devices. Here, the growth of kinked single-crystal In2O3 nanostructures consisting of a nanocone base and a nanowire tip with an epitaxial and defect-free transition is demonstrated for the first time. By tailoring the growth conditions, a reliable switching of the growth direction from [111] to [110] or [112] is observed when the Au catalyst nanoparticles at the apexes of the nanocones shrink below approximate to 100 nm. The natural formation of kinked nanoarchitectures at constant growth pressures is related to the size-dependent free energy that changes for different orientations of the nanowires. The results suggest that the mechanism of forming such kinked nanocone-nanowire nanostructures in well-controlled growth environment may be universal for a wide range of functional materials.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
Times cited: 2
DOI: 10.1002/ADFM.201600142
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“Evidence of strain induced structural change in hetero-epitaxial NdNiO3 thin films with metal-insulator transition”. Laffez P, Lebedev OI, Ruello P, Desfeux R, Banerjee G, Capon F, European physical journal: applied physics 25, 25 (2004). http://doi.org/10.1051/epjap:2003087
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.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 0.684
Times cited: 12
DOI: 10.1051/epjap:2003087
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