|
“Microstructural investigation of BaTiO3 thin films deposited on (001) MgO”. Lei CH, Van Tendeloo G, Siegert M, Schubert J, Journal of materials research 17, 1923 (2002). http://doi.org/10.1557/JMR.2002.0285
Abstract: The microstructure of BaTiO3 thin films, epitaxially deposited on (001) MgO by pulsed laser ablation, has been investigated by transmission electron microscopy. The films are always c-axis-orientated, but dislocations, {111} stacking faults, and antiphase boundaries are frequently observed. Conventional TEM and high-resolution microscopy allow one to deduce the Burgers vectors of dislocations as b(1) = <100> or b(2) = <110>, both being perfect dislocations. Most extrinsic stacking faults are ending at 1/3<112> or 1/3<111> partial dislocations; the displacement vector of the antiphase boundaries is 1/2<101>. Studying the interfacial structure by means of zone images taken along [100] and [110] shows that the misfit is mainly released by dislocations with Burgers vectors of 1/2<110> and 1/2<101>.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.673
Times cited: 8
DOI: 10.1557/JMR.2002.0285
|
|
|
“Modeling ultrashort laser-induced emission from a negatively biased metal”. Wendelen W, Mueller BY, Autrique D, Bogaerts A, Rethfeld B, Applied physics letters 103, 221603 (2013). http://doi.org/10.1063/1.4830378
Abstract: A theoretical study of ultrashort laser-induced electron emission from a negatively biased metallic cathode has been performed. Classical as well as tunneling electron emission mechanisms are considered. It was found that electron emission is governed by an interplay of processes inside as well as above the cathode. A hybrid model is proposed, where the electron distribution within the target is retrieved from Boltzmann scattering integrals, while the charge distribution above it is studied by a Particle-In-Cell simulation. The results indicate that non-equilibrium effects determine the initial emission process, whereas the space charge above the target suppresses the effectively emitted charge.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.411
Times cited: 8
DOI: 10.1063/1.4830378
|
|
|
“Orientational ordering in solid C60 fullerene-cubane”. Verberck B, Vliegenthart GA, Gompper G, The journal of chemical physics 130, 154510 (2009). http://doi.org/10.1063/1.3098550
Abstract: We study the structure and phase behavior of fullerene-cubane C60·C8H8 by Monte Carlo simulation. Using a simple potential model capturing the icosahedral and cubic symmetries of its molecular constituents, we reproduce the experimentally observed phase transition from a cubic to an orthorhombic crystal lattice and the accompanying rotational freezing of the C60 molecules. We elaborate a scheme to identify the low-temperature orientations of individual molecules and to detect a pattern of orientational ordering similar to the arrangement of C60 molecules in solid C60. Our configuration of orientations supports a doubled periodicity along one of the crystal axes.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.965
Times cited: 8
DOI: 10.1063/1.3098550
|
|
|
“Phase modulation in pulsed dual-frequency capacitively coupled plasmas”. Wen D-Q, Zhang Q-Z, Jiang W, Song U-H, Bogaerts A, Wang Y-N, Journal of applied physics 115, 233303 (2014). http://doi.org/10.1063/1.4884225
Abstract: Particle-in-cell/Monte Carlo collision simulations, coupled with an external circuit, are used to investigate the behavior of pulsed dual-frequency (DF) capacitively coupled plasmas (CCPs). It is found that the phase shift θ between the high (or low) frequency source and the pulse modulation has a great influence on the ion density and the ionization rate. By pulsing the high frequency source, the time-averaged ion density shows a maximum when θ = 90∘. The time-averaged ion energy distribution functions (IEDFs) at the driven electrode, however, keep almost unchanged, illustrating the potential of pulsed DF-CCP for independent control of ion density (and flux) and ion energy. A detailed investigation of the temporal evolution of the plasma characteristics indicates that several high frequency harmonics can be excited at the initial stage of a pulse period by tuning the phase shift θ, and this gives rise to strong sheath oscillations, and therefore high ionization rates. For comparison, the pulsing of the low frequency source is also studied. In this case, the ion density changes slightly as a function of time, and the time-averaged ion density shows the same trend as in the HF modulation for different phase shifts θ. Moreover, the time-averaged IEDFs at the driven electrode can be modulated, showing the potential to reduce the maximum ion bombardment energy.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.068
Times cited: 8
DOI: 10.1063/1.4884225
|
|
|
“Quantum-confined magneto-Stark effect in diluted magnetic semiconductor coupled quantum wells”. Chang K, Xia JB, Wu HB, Feng SL, Peeters FM, Applied physics letters 80, 1788 (2002). http://doi.org/10.1063/1.1459491
Abstract: The magneto-Stark effect in a diluted magnetic semiconductor (DMS) coupled quantum well (CQW) induced by an in-plane magnetic field is investigate theoretically. Unlike the usual electro-Stark effects, in a DMS CQW the Lorenz force leads to a spatially separated exciton. The in-plane magnetic field can shift the ground state of the magnetoexciton from a zero in-plane center of mass (CM)/momentum to a finite CM momentum, and render the ground state of magnetoexciton stable against radiative recombination due to momentum conservation. (C) 2002 American Institute of Physics.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 8
DOI: 10.1063/1.1459491
|
|
|
“Quantum transport in an ultra-thin SOI MOSFET: influence of the channel thickness on the I-V characteristics”. Croitoru MD, Gladilin VN, Fomin VM, Devreese JT, Magnus W, Schoenmaker W, Sorée B, Solid state communications 147, 31 (2008). http://doi.org/10.1016/j.ssc.2008.04.025
Keywords: A1 Journal article; Theory of quantum systems and complex systems; Condensed Matter Theory (CMT); Electron microscopy for materials research (EMAT)
Impact Factor: 1.554
Times cited: 8
DOI: 10.1016/j.ssc.2008.04.025
|
|
|
“Size distribution and magnetic behavior of lead inclusions in silicon single crystals”. Milants K, Verheyden J, Barancira T, Deweerd W, Pattyn H, Bukshpan S, Williamson DL, Vermeiren F, Van Tendeloo G, Vlekken C, Libbrecht S, van Haesendonck C, Journal of applied physics 81, 2148 (1997)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.068
Times cited: 8
|
|
|
“Three-dimensional ferromagnetic architectures with multiple metastable states”. Nasirpouri F, Engbarth MA, Bending SJ, Peter LM, Knittel A, Fangohr H, Milošević, MV, Applied physics letters 98, 222506 (2011). http://doi.org/10.1063/1.3595339
Abstract: We demonstrate controllable dual-bath electrodeposition of nickel on architecture-tunable three-dimensional (3D) silver microcrystals. Magnetic hysteresis loops of individual highly faceted Ag-Ni core-shell elements reveal magnetization reversal that comprises multiple sharp steps corresponding to different stable magnetic states. Finite-element micromagnetic simulations on smaller systems show several jumps during magnetization reversal which correspond to transitions between different magnetic vortex states. Structures of this type could be realizations of an advanced magnetic data storage architecture whereby each element represents one multibit, storing a combination of several conventional bits depending on the overall number of possible magnetic states associated with the 3D core-shell shape.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 8
DOI: 10.1063/1.3595339
|
|
|
“Transmission electron microscopy studies of (111) twinned silver halide microcrystals”. Goessens C, Schryvers D, van Landuyt J, Microscopy research and technique 42, 85 (1998). http://doi.org/10.1002/(SICI)1097-0029(19980715)42:2<85::AID-JEMT3>3.0.CO;2-M
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.147
Times cited: 8
DOI: 10.1002/(SICI)1097-0029(19980715)42:2<85::AID-JEMT3>3.0.CO;2-M
|
|
|
“Tuning of anisotropy in two-electron quantum dots by spin-orbit interactions”. Liu Y, Cheng F, Li XJ, Peeters FM, Chang K, Applied physics letters 99, 032102 (2011). http://doi.org/10.1063/1.3610961
Abstract: We investigate the influence of the spin-orbit interactions (SOIs) on the electron distribution and the optical absorption of a two-electron quantum dot. It is shown that the interplay between the SOIs makes the two-electron quantum dot behave like two laterally coupled quantum dots and the anisotropic distribution can be rotated from [110] to [11®0] by reversing the direction of the perpendicular electric field and detect it through the optical absorption spectrum.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 8
DOI: 10.1063/1.3610961
|
|
|
“Skyrmion-induced bound states on the surface of three-dimensional topological insulators”. Andrikopoulos D, Sorée B, De Boeck J, Journal of applied physics 119, 193903 (2016). http://doi.org/10.1063/1.4950759
Abstract: The interaction between the surface of a 3D topological insulator and a skyrmion/anti-skyrmion structure is studied in order to investigate the possibility of electron confinement due to the skyrmion presence. Both hedgehog (Neel) and vortex (Bloch) skyrmions are considered. For the hedgehog skyrmion, the in-plane components cannot be disregarded and their interaction with the surface state of the topological insulator (TI) has to be taken into account. A semi-classical description of the skyrmion chiral angle is obtained using the variational principle. It is shown that both the hedgehog and the vortex skyrmion can induce bound states on the surface of the TI. However, the number and the properties of these states depend strongly on the skyrmion type and the skyrmion topological number N-Sk. The probability densities of the bound electrons are also derived where it is shown that they are localized within the skyrmion region. Published by AIP Publishing.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.068
Times cited: 8
DOI: 10.1063/1.4950759
|
|
|
“Can p-channel tunnel field-effect transistors perform as good as n-channel?”.Verhulst AS, Verreck D, Pourghaderi MA, Van de Put M, Sorée B, Groeseneken G, Collaert N, Thean AV-Y, Applied physics letters 105, 043103 (2014). http://doi.org/10.1063/1.4891348
Abstract: We show that bulk semiconductor materials do not allow perfectly complementary p- and n-channel tunnel field-effect transistors (TFETs), due to the presence of a heavy-hole band. When tunneling in p-TFETs is oriented towards the gate-dielectric, field-induced quantum confinement results in a highest-energy subband which is heavy-hole like. In direct-bandgap IIIV materials, the most promising TFET materials, phonon-assisted tunneling to this subband degrades the subthreshold swing and leads to at least 10x smaller on-current than the desired ballistic on-current. This is demonstrated with quantum-mechanical predictions for p-TFETs with tunneling orthogonal to the gate, made out of InP, In0.53Ga0.47As, InAs, and a modified version of In0.53Ga0.47As with an artificially increased conduction-band density-of-states. We further show that even if the phonon-assisted current would be negligible, the build-up of a heavy-hole-based inversion layer prevents efficient ballistic tunneling, especially at low supply voltages. For p-TFET, a strongly confined n-i-p or n-p-i-p configuration is therefore recommended, as well as a tensily strained line-tunneling configuration. (C) 2014 AIP Publishing LLC.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 8
DOI: 10.1063/1.4891348
|
|
|
“Stress dependence of the suspended graphene work function : vacuum Kelvin probe force microscopy and density functional theory”. Volodin A, Van Haesendonck C, Leenaerts O, Partoens B, Peeters FM, Applied physics letters 110, 193101 (2017). http://doi.org/10.1063/1.4982931
Abstract: We report on work function measurements on graphene, which is exfoliated over a predefined array of wells in silicon oxide, by Kelvin probe force microscopy operating in a vacuum. The obtained graphene sealed microchambers can support large pressure differences, providing controllable stretching of the nearly impermeable graphene membranes. These measurements allow detecting variations of the work function induced by the mechanical stresses in the suspended graphene where the work function varies linearly with the strain and changes by 62 +/- 2 meV for 1 percent of strain. Our related ab initio calculations result in a work function variation that is a factor of 1.4 larger than the experimental value. The limited discrepancy between the theory and the experiment can be accounted for by a charge transfer from the unstrained to the strained graphene regions. Published by AIP Publishing.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 8
DOI: 10.1063/1.4982931
|
|
|
“Topological Dirac semimetal phase in <tex>, $GexSny alloys”. Kong X, Li L, Peeters FM, Applied physics letters 112, 251601 (2018). http://doi.org/10.1063/1.5037121
Abstract: Recently, two stable allotropes (germancite and stancite) for the group IV elements (Ge and Sn) with a staggered layered dumbell structure were proposed to be three-dimensional (3D) topological Dirac semimetals [Phys. Rev. B 93, 241117 (2016)]. A pair of Dirac points is on the rotation axis away from the time-reversal invariant momentum, and the stability of the 3D bulk Dirac points is protected by the C-3 rotation symmetry. Here, we use the first principles calculations to investigate GexSny alloys which share the same rhombohedral crystal structure with the space group of D-3d(6). Six GexSny alloys are predicted to be energetically and dynamically stable, where (x, y) = (8, 6) and (6, 8) and the alpha and beta phases of (10, 4) and (4, 10). Our results demonstrate that all the six GexSny alloys are topological Dirac semimetals. The different nontrivial surface states and surface Fermi arcs are identified. Our work will substantially enrich the family of 3D Dirac semimetals which are within the reach of experimental realization. Published by AIP Publishing.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 8
DOI: 10.1063/1.5037121
|
|
|
“Direct evidence for the existence of multi-walled carbon nanotubes with hexagonal cross-sections”. He Z, Ke X, Bals S, Van Tendeloo G, Carbon 50, 2524 (2012). http://doi.org/10.1016/j.carbon.2012.01.075
Abstract: Carbon nanotubes (CNTs) with a polygonal cross-section have been paid increasing attention since their three-dimensional structure is related to specific physical properties, which are found to be different in comparison to CNTs with a circular cross-section. Here, we report the existence of novel multi-walled CNTs yielding walls with a rounded-hexagonal configuration. This structure was directly confirmed for the first time by both cross-sectional transmission electron microscopy and electron tomography. The morphology of the Fe catalytic particle also exhibits hexagonal characteristics, and is proposed as the origin of the formation of the rounded-hexagonal walls of the CNT. This observation is of great importance with respect to the design of polygonal (such as pentagonal or hexagonal) cross-sectional CNTs. By controlling the morphology of the catalytic nanoparticles it will be possible to grow CNTs with desired electronic and mechanical properties.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 6.337
Times cited: 8
DOI: 10.1016/j.carbon.2012.01.075
|
|
|
“Energy-filtering TEM and electron energy-loss spectroscopy of double structure tabular microcrystals of silver halide emulsions”. Oleshko V, Gijbels R, Jacob W, Journal of microscopy 183, 27 (1996). http://doi.org/10.1046/j.1365-2818.1996.73068.x
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.331
Times cited: 8
DOI: 10.1046/j.1365-2818.1996.73068.x
|
|
|
“Polarizability induced cooperative proton ordering, coexistence of order/disorder and displacive dynamics and isotope effects in hydrogen-bonded systems”. Bussmann-Holder A, Dalal N, Michel KH, The journal of physics and chemistry of solids
T2 –, Williamsburg Workshop on Ferroelectrics 99, JAN 31-FEB 03, 1999, WILLIAMSBURG, VIRGINIA 61, 271 (2000). http://doi.org/10.1016/S0022-3697(99)00292-9
Abstract: Despite the general belief that hydrogen-bonded ferro- and antiferroelectrics undergo a pure order/disorder transition at the structural instability, new NMR data and a new theoretical concept yield convincing evidence that a pronounced displacive component is present in these systems, which modifies substantially the temperature dependencies of the tunnel and lattice mode frequencies. The experiments and their interpretation are presented. (C) 1999 Elsevier Science Ltd. All rights reserved.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.059
Times cited: 8
DOI: 10.1016/S0022-3697(99)00292-9
|
|
|
“Quantitative 3-D morphologic and distributional study of Ni4Ti3 precipitates in a Ni51Ti49 single crystal alloy”. Cao S, Pourbabak S, Schryvers D, Scripta materialia 66, 650 (2012). http://doi.org/10.1016/j.scriptamat.2012.01.045
Abstract: The size, shape and distribution of Ni4Ti3 precipitates in Ni51Ti49 single crystals annealed under stress-free and 〈1 1 1〉B2 compressive conditions are studied via focused ion beam/scanning electron microscopy slice-and-view. The precipitates in the stress-free material grow in autocatalytic pockets with larger size, lower number density, flatter shape and larger inter-particle distance than in the compressed material. Nevertheless, a new quantification method called water penetration reveals that, due to the precipitate alignment, martensite can grow more easily in the compressed material perpendicular to the compression direction.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.747
Times cited: 8
DOI: 10.1016/j.scriptamat.2012.01.045
|
|
|
“A weak compatibility condition for precipitation with application to the microstructure of PbTe-Sb2Te3 thermoelectrics”. Chen X, Cao S, Ikeda T, Srivastava V, Snyder GJ, Schryvers D, James RD, Acta materialia 59, 6124 (2011). http://doi.org/10.1016/j.actamat.2011.06.025
Abstract: We propose a weak condition of compatibility between phases applicable to cases exhibiting full or partial coherence and Widmanstätten microstructure. The condition is applied to the study of Sb2Te3 precipitates in a PbTe matrix in a thermoelectric alloy. The weak condition of compatibility predicts elongated precipitates lying on a cone determined by a transformation stretch tensor. Comparison of this cone with the long directions of precipitates determined by a slice-and-view method of scanning electron microscopy combined with focused ion beam sectioning shows good agreement between theory and experiment. A further study of the morphology of precipitates by the Eshelby method suggests that interfacial energy also plays a role and gives an approximate value of interfacial energy per unit area of 250 dyn cm−1.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.301
Times cited: 8
DOI: 10.1016/j.actamat.2011.06.025
|
|
|
“Nanofilms as quantum-engineered multiband superconductors : the Ginzburg-Landau theory”. Shanenko AA, Orlova NV, Vagov A, Milošević, MV, Axt VM, Peeters FM, Europhysics letters 102, 27003 (2013). http://doi.org/10.1209/0295-5075/102/27003
Abstract: Recently fabricated single-crystalline atomically flat metallic nanofilms are in fact quantum-engineered multiband superconductors. Here the multiband structure is dictated by the nanofilm thickness through the size quantization of the electron motion perpendicular to the nanofilm. This opens the unique possibility to explore superconductivity in well-controlled multi-band systems. However, a serious obstacle is the absence of a convenient and manageable theoretical tool to access new physical phenomena in such quasi-two-dimensional systems, including interplay of quantum confinement and fluctuations. Here we cover this gap and construct the appropriate multiband Ginzburg-Landau functional for nano-thin superconductors. Copyright (C) EPLA, 2013
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.957
Times cited: 8
DOI: 10.1209/0295-5075/102/27003
|
|
|
“The ground states of the two-component order parameter superconductor”. Doria MM, de Romaguera ARC, Peeters FM, Europhysics letters 92, 17004 (2010). http://doi.org/10.1209/0295-5075/92/17004
Abstract: We show that in presence of an applied external field the two-component order parameter superconductor falls in two categories of ground states, namely, in the traditional Abrikosov ground state or in a new ground state fitted to describe a superconducting layer with texture, that is, patched regions separated by a phase difference of pi. The existence of these two kinds of ground states follows from the sole assumption that the total supercurrent is the sum of the two individual supercurrents and is independent of any consideration about the free energy expansion. Uniquely defined relations between the current density and the superfluid density hold for these two ground states, which also determine the magnetization in terms of average values of the order parameters. Because these ground-state conditions are also Bogomolny equations we construct the free energy for the two-component superconductor which admits the Bogomolny solution at a special coupling value. Copyright (C) EPLA, 2010
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.957
Times cited: 8
DOI: 10.1209/0295-5075/92/17004
|
|
|
“Optical bistability and multistability in four-level systems”. Chen Z, Feng X, Xu Y, Yu MY, Physica scripta 68, 199 (2003). http://doi.org/10.1238/Physica.Regular.068a00199
Abstract: The optical behavior of a four-level system in a ring cavity driven by two coherent laser fields is studied. One laser field is treated as the incident field and the other the control field, respectively. It is found that there is optical transparency when the difference between the two frequency detunings of the incident and control fields from the corresponding atomic transition frequencies is zero. Optical bistability can be produced and controlled by increasing the magnitude of the frequency difference. The bistable hysteresis becomes larger when the frequency difference is increased. Further increase of the latter can lead to onset of multistability.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 1.28
Times cited: 8
DOI: 10.1238/Physica.Regular.068a00199
|
|
|
“Quantum magnetotransport of a 2-dimensional electron-gas subject to periodic electric or magnetic modulations”. Vasilopoulos, Peeters FM, Physica scripta : supplements
T2 –, 11TH GENERAL CONF OF THE CONDENSED MATTER DIVISION OF THE EUROPEAN, PHYSICAL SOC, APR 08-11, 1991, EXETER, ENGLAND T39, 177 (1991). http://doi.org/10.1088/0031-8949/1991/T39/027
Abstract: Electrical transport properties of the two-dimensional electron gas are studied in the presence of a perpendicular magnetic field B = Bz and of a weak one-dimensional electric (V0 cos (Kx)) or magnetic (B0 = B0 cos (Kx)z) modulation where B0 << B, K = 2-pi/a, and a is the modulation period. In either case the discrete Landau levels broaden into bands whose width: (1) is proportional to the modulation strength, (2) it oscillates with B, and (3) it gives rise to magnetoresistance oscillations, at low B, that are different in period and temperature dependence from the Shubnikov-de Haas (SdH) ones, at higher B. For equal energy modulation strengths, V0 = heB0/m*, the magnetic bandwidth at the Fermi energy is about one order of magnitude larger than the electric one. The same holds for the oscillation amplitude of the electrical magnetoresistivity tensor. For two-dimensional modulations the energy spectrum has the same structure but with different scales. For weak magnetic fields and equal modulation strengths the gaps in the spectrum can be much larger in the magnetic case thus making easier the observability of the spectrum's fine structure.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.126
Times cited: 8
DOI: 10.1088/0031-8949/1991/T39/027
|
|
|
“Quantum magnetotransport of a two-dimensional electron gas subject to periodic electric and magnetic modulations”. Vasilopoulos P, Peeters FM, Physica scripta T39, 177 (1991)
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.126
Times cited: 8
|
|
|
“A layered iron-rich 2234-type with a mixed valence of iron: the ferrimagnetic Tl-doped Fe2(Sr2-\varepsilonTl\varepsilon)Sr3Fe4O14.65”. Lepoittevin C, Malo S, Nguyen N, Hebert S, Van Tendeloo G, Hervieu M, Chemistry of materials 20, 6468 (2008). http://doi.org/10.1021/cm8014385
Abstract: A new Tl-doped strontium ferrite Fe2(Sr2-Tl)Sr3Fe4O14.65, with an original structure, has been synthesized and structurally characterized by powder X-ray diffraction and transmission electron microscopy. The TGA and Mssbauer studies evidence a mixed valence of iron. The structure exhibits a commensurate modulation, with a F-type subcell a ≈ b ≈ 5.4 Å (≈ ap√2), c ≈ 42 Å with a modulation vector q = αa* with α = 0.4. The supercell parameters have been refined as a= 27.1101(8) Å, b= 5.5187(2) Å and c= 42.0513(9) Å, in the space group Fmmm. The electron diffraction and electron microscopy data of this novel ferrite show that it can be described as a FeTl-2234-type structure corresponding to the intergrowth of a quadruple perovskite slice [(SrFeO2.8)4], with a complex rock salt related slice [Fe2(Sr2-Tl)O3.4]∞, built up of one double iron layer [Fe2O2.4] sandwiched between two [SrO] layers. The HRTEM images show that the oxygen atoms and vacancies are randomly distributed in the perovskite layers while the HAADF STEM images evidence the absence of Tl segregation in the matrix. Fe2(Sr2-Tl)Sr3Fe4O14.65 exhibits a very large value of χ (11emu/mol) at 5 K, which remains large at 400 K; the M(H) loop presents a shape characteristic of ferrimagnetism, with a large coercive field of 0.3 T. The value of magnetization saturates at 400 K at 0.68 μB/Fe. At 10 K, the value of magnetization reaches a maximum of 2 μB/Fe. The resistivity presents a semiconducting-like behavior, with ρ 800 Ω·cm at 300 K.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 8
DOI: 10.1021/cm8014385
|
|
|
“Computer simulations for processing plasmas”. Bogaerts A, de Bleecker K, Georgieva V, Kolev I, Madani M, Neyts E, Plasma processes and polymers 3, 110 (2006). http://doi.org/10.1002/ppap.200500065
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.846
Times cited: 8
DOI: 10.1002/ppap.200500065
|
|
|
“Mixed tellurides Ni3-xGaTe2 (0\leq x\leq0.65): crystal and electronic structures, properties, and nickel deficiency effects on vacancy ordering”. Isaeva AA, Makarevich ON, Kutznetsov AN, Doert T, Abakumov AM, Van Tendeloo G, European journal of inorganic chemistry , 1395 (2010). http://doi.org/10.1002/ejic.200901027
Abstract: The Ni3-xGaTe2 series of compounds (0 x 0.65) was synthesized by a high-temperature ceramic technique at 750 °C. Crystal structures of three compounds in the series were determined by X-ray powder diffraction: Ni2.98(1)GaTe2 (RI = 0.042, Rp = 0.023, Rwp = 0.035), Ni2.79(1)GaTe2 (RI = 0.053, Rp = 0.028, Rwp = 0.039), Ni2.58(1)GaTe2 (RI = 0.081, Rp = 0.037, Rwp = 0.056); the structures were verified by electron diffraction and, for the former compound, high-resolution electron microscopy. The compounds crystallize in a hexagonal lattice with P63/mmc, and the structures can be regarded as a hexagonal close-packed array with a -Ga-Te-Te- stacking sequence. The octahedral and trigonal bipyramidal voids in the hcp structure are selectively filled with Ni atoms to form one entirely occupied and two partially occupied sites, thus allowing variations in the nickel content in the series of compounds Ni3-xGaTe2 (0 x 0.65). A superstructure with asup = 2asub (P63/mmc) has been identified for Ni3-xGaTe2 (0.5 x 0.65) by electron diffraction. Real-space, high-resolution images confirm an ordering of Ni atoms and vacancies inthe ab plane. Quantum-chemical calculations performed forNi3-xGaTe2 (x = 0, 0.25, 0.75, 1) suggest anisotropic metallic conductivity and Pauli paramagnetic behavior that are experimentally confirmed for Ni3GaTe2.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.444
Times cited: 8
DOI: 10.1002/ejic.200901027
|
|
|
“Au2Sx/CdS nanorods by cation exchange : mechanistic insights into the competition between cation-exchange and metal ion reduction”. Kundu S, Kundu P, Van Tendeloo G, Ravishankar N, Small 10, 3895 (2014). http://doi.org/10.1002/smll.201400524
Abstract: Thumbnail image of graphical abstract It is well known that metals with higher electron affinity like Au tend to undergo reduction rather than cation-exchange. It is experimentally shown that under certain conditions cation-exchange is dominant over reduction. Thermodynamic calculation further consolidates the understanding and paves the way for better predictability of cation-exchange/reduction reactions for other systems.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 8.643
Times cited: 8
DOI: 10.1002/smll.201400524
|
|
|
“One-pot synthesis of carbon-coated nanostructured iron oxide on few-layer graphene for lithium-ion batteries”. Sun Z, Madej E, Wiktor, Sinev I, Fischer RA, Van Tendeloo G, Muhler M, Schuhmann W, Ventosa E, Chemistry: a European journal 21, 16154 (2015). http://doi.org/10.1002/chem.201501935
Abstract: Nanostructure engineering has been demonstrated to improve the electrochemical performance of iron oxide based electrodes in Li-ion batteries (LIBs). However, the synthesis of advanced functional materials often requires multiple steps. Herein, we present a facile one-pot synthesis of carbon-coated nanostructured iron oxide on few-layer graphene through high-pressure pyrolysis of ferrocene in the presence of pristine graphene. The ferrocene precursor supplies both iron and carbon to form the carbon-coated iron oxide, while the graphene acts as a high-surface-area anchor to achieve small metal oxide nanoparticles. When evaluated as a negative-electrode material for LIBs, our composite showed improved electrochemical performance compared to commercial iron oxide nanopowders, especially at fast charge/discharge rates.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 5.317
Times cited: 8
DOI: 10.1002/chem.201501935
|
|
|
“Bilayer crystals of charged magnetic dipoles : structure and phonon spectrum”. Ramos IRO, Ferreira WP, Munarin FF, Farias GA, Peeters FM, Physical review : E : statistical, nonlinear, and soft matter physics 85, 051404 (2012). http://doi.org/10.1103/PhysRevE.85.051404
Abstract: We study the structure and phonon spectrum of a two-dimensional bilayer system of classical charged dipoles oriented perpendicular to the plane of the layers for equal density in each layer. This system can be tuned through six different crystalline phases by changing the interlayer separation or the charge and/or dipole moment of the particle. The presence of the charge on the dipole particles is responsible for the nucleation of five staggered phases and a disordered phase which are not found in the magnetic dipole bilayer system. These extra phases are a consequence of the competition between the repulsive Coulomb and the attractive dipole interlayer interaction. We present the phase diagram and determine the order of the phase transitions. The phonon spectrum of the system was calculated within the harmonic approximation, and a nonmonotonic behavior of the phonon spectrum is found as a function of the effective strength of the interparticle interaction. The stability of the different phases is determined.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.366
Times cited: 8
DOI: 10.1103/PhysRevE.85.051404
|
|