“Crystal chemistry of mercury based layered cuprates and oxycarbonates”. Raveau B, Hervieu M, Michel C, Martin C, Maignan A, Van Tendeloo G Narosa, New Delhi, page 132 (1995).
Keywords: H3 Book chapter; Electron microscopy for materials research (EMAT)
|
“A cyclotron resonance study of the resonant polaron coupling in CdTe/CdMgTe quantum wells”. Chang CC, Michels JG, Cheng HH, Nicholas RJ, Peeters FM, Wu XG, Ossau W, Waag A, Landwehr G, , 383 (1997)
Keywords: P3 Proceeding; Condensed Matter Theory (CMT)
|
“Molecular structure, crystal field and orientational order in solid C60”. Lamoen D, Michel KH s.l., page 183 (1994).
Keywords: H1 Book chapter; Condensed Matter Theory (CMT)
|
“Orientation fluctuations, diffuse scattering and orientational order in solid C60”. Michel KH, Copley JRD World Scientific, Singapore, page 381 (1996).
Keywords: H3 Book chapter; Condensed Matter Theory (CMT)
|
“Orientational disorder and order in C60-fullerite and in MC60-alkali metal fullerides”. Nikolaev AV, Michel KH, Copley JRD Plenum Press, New York, page 183 (1999).
Keywords: H3 Book chapter; Condensed Matter Theory (CMT)
|
“Theory of crystal structures of polymerized C60-fullerite and fullerides AC60, A=K, Rb, Cs”. Michel KH, Nikolaev AV, Verberck B s.l. (2001).
Keywords: H1 Book chapter; Condensed Matter Theory (CMT)
|
“Orientational order and disorder in solid C60 : theory and diffraction experiments”. Michel KH, Lamoen D, David WIF, Acta crystallographica: section A: foundations of crystallography 51, 365 (1995). http://doi.org/10.1107/S0108767394013280
Abstract: Starting from a microscope model of the intermolecular potential, a unified description is presented of the Bragg scattering law in the orientationally disordered and in the ordered phase of solid C-60. The orientational structure factor is expanded in terms of symmetry-adapted surface harmonics. The expansion coefficients are calculated from theory and compared with experiment Their temperature evolution is studied in the disordered phase at the 260 K transitions and in the ordered phase. In the ordered phase, new results from high-resolution neutron powder diffraction are given. In the disordered phase, space group Fm $($) over bar$$ 3m, the reflections have A(1g) symmetry; in the ordered phase, space group Pa $$($) over bar 3, reflections of T-2g symmetry appear and in addition the A(1g) reflections are renormalized. The orientational density distribution is calculated. The effective crystal-field potential is constructed, its temperature evolution in the ordered phase is studied and related to the occurrence of an orientational glass.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.307
Times cited: 14
DOI: 10.1107/S0108767394013280
|
“Molecular terms and optical transitions of C60n+/- molecular ions”. Nikolaev AV, Michel KH, AIP conference proceedings
T2 –, 16th International Winterschool on Electronic Properties of Novel, Materials, MAR 02-09, 2002, KIRCHBERG, AUSTRIA , 417 (2002)
Abstract: We have studied the molecular energy terms of the hole configurations (h(u)(+))(m), m=2,3,4,5 of C-60(m+) cations and the electronic configurations (t(1u))(n) n=2,3,4, as well as (t(1u))(n-1)t(1g) of the C-60(n-) anions. The lowest terms (within an energy span of 0.03 eV) for C-60(2+) are three triplets T-3(1g), (3)G(g), T-3(2g) and for C-60(3+) are three quartets T-4(1u), (4)G(u), T-4(2u), which favor Jahn-Teller distortions. For the ground state of C-60(2-) we find a triplet T-3(1g) in agreement with Hund's rules. Our method takes into account intramolecular direct and exchange multipolar Coulomb interactions.
Keywords: P1 Proceeding; Condensed Matter Theory (CMT)
|
“Ab initio approach to superexchange interactions in alkali doped fullerides AC60”. Nikolaev AV, Michel KH, AIP conference proceedings
T2 –, 18th International Winterschool/Euroconference on Electronic Properties, of Novel Materials, MAR 06-JUN 13, 2004, Kirchberg, AUSTRIA , 393 (2004). http://doi.org/10.1063/1.1812115
Abstract: The superexchange interactions between the fullerenes arise as a result of the electron transfer from the C-60 molecule to the alkali atom and back. We present a scheme, which is a configuration interaction approach based on the valence bond (Heitler-London) method. The effect of superexchange is described together with chemical bonding by constructing and solving a secular equation, rather than by using a perturbation treatment. We have considered 180degrees and 90degrees superexchange for the C-60 Cs-C-60 pathways. The calculations account for unusual electronic properties of polymer orthorhombic and quenched cubic phases of CsC60: two lines in nuclear magnetic resonance experiments, the development of a spin-singlet ground state and a decrease of magnetic susceptibility as T-->0.
Keywords: P1 Proceeding; Condensed Matter Theory (CMT)
DOI: 10.1063/1.1812115
|
“Proton tunneling and nonlinear polarizability effects in hydrogen-bonded ferroelectrics”. Bussmann-Holder A, Michel KH, AIP conference proceedings
T2 –, 5th Williamsburg Workshop on 1st-Principles Calculations for, Ferroelectrics, FEB 01-04, 1998, WILLIAMSBURG, VA , 202 (1998)
Abstract: Hydrogen-bonded ferroelectrics are modelled by a coupled spin/nonlinear lattice (polarizability) interaction Hamiltonian, where specifically the geometry of the hydrogen bond is included. The model leads to a structural phase transition and describes correctly the isotope effect due to the substitution H/D in hydrogen-bonded systems in terms of bond length changes.
Keywords: P1 Proceeding; Condensed Matter Theory (CMT)
|
“Mercator maps of orientations of a C60 molecule in single-walled nanotubes with distinct radii”. Michel KH, Verberck B, Nikolaev A, AIP conference proceedings 786, 69 (2005)
Abstract: We study the confinement of a C-60 molecule encapsulated in a cylindrical nanotube as a function of the tube radius. Drawing the Mercator maps of the potential, we find two distinct molecular orientations; for tubes with small radii, R-T less than or similar to 7 angstrom, a fivefold axis of the molecule coincides with the tube long axis, for larger radii, R-T less than or similar to 8 angstrom, a threefold axis of the molecule coincides with the tube long axis. These different orientations are caused by the relative importance of the repulsive and the attractive parts of the van der Waals potentials of the molecule with the tube wall for small and large tubes respectively. Experimental evidence is provided by the apparent splitting of A(g) modes of the C-60 molecule in resonant Raman scattering.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
|
“Orientational charge density waves and the metal-insulator transition in polymerized KC60”. Verberck B, Nikolaev AV, Michel KH, AIP conference proceedings 723, 339 (2004)
Abstract: Polymerized KC60 undergoes a structural phase transition accompanied by a metal-insulator transition around 50 K. To explain the structural aspect, a mechanism involving small orientational deviations of the valence electron density on every C-60 monomer orientational charge density waves (OCDWs) – has already been proposed earlier. In the present work, we address the metal-insulator transition using the OCDW concept. We are inspired by the analogy between a polymer chain exhibiting an OCDW and a linear atomic chain undergoing a static lattice deformation doubling the unit cell: such a deformation implies a band gap at the zone boundary, yielding an insulating state (Peierls instability). Within our view, a similar mechanism occurs in polymerized KC60; the OCDW plays the role of the lattice deformation. We present tight-binding band structure calculations and conclude that the metal-insulator transition can indeed be explained using OCDWs, but that the threedimensionality of the crystal plays an unexpected key role.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
|
“Stabilization of mercury-based superconductors by foreign cations”. Raveau B, Michel C, Hervieu M, Van Tendeloo G, Maignan A, Annales de chimie (1914)
T2 –, 4th North-African Materials Science Symposium (JMSM 94), NOV 23-24, 1994, CASABLANCA, MOROCCO 19, 487 (1994)
Abstract: The recently discovered superconducting mercury-based cuprates HgBa2Can-1CunO2n+2+delta have proved difficult to synthesize as single phases and are sensitive to environment (CO2, moisture). The present paper gives an overview of new series mercury based superconductors, whose stabilisation is based on the fact that a foreign cation with a higher valency than Hg(II) must be introduced in the mercury layers, in order to fill up partially the oxygen vacancies of these layers. By this method, several new series of superconductors involving strontium instead of barium with critical temperatures ranging from 27 K to 95 K have been isolated : Hg0.5Bi0.5Sr2-xLaxCuO4+delta, Hg(0.5)Bi(0.5)Sr(2)Ca(1-x)R(x)Cu(2)O(6+delta) (R Y, Nd, Pr), Pb0.7Hg0.3Sr2-xLaxCuO4+delta, Pb(0.7)Hg(0.3)Sr(2)Ca(1-x)R(x)Cu(2)O(6+delta) (R = Y, Nd) Hg(1-x)Pr(x)Sr(2)A(1-x')Pr(x') Cu2O6+delta (A = Sr, Ca), Pb0.7Hg0.3Sr2Cu2CO3O7 and Hg1-xCrxSr2CuO4+delta. The behaviour of the praseodymium cuprates that exhibit a rather sharp transition and reach a Tc of 85 K is especially discussed. A method to synthesize new ''Ba-Hg'' superconducting cuprates with the 1212 structure at normal pressure with a Tc up to 110 K is also presented.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 2
|
“Sequence of orientational phase transitions in solid C60”. Michel KH, Chemical physics letters 193, 478 (1992). http://doi.org/10.1016/0009-2614(92)85835-X
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.897
Times cited: 14
DOI: 10.1016/0009-2614(92)85835-X
|
“Novel, oxygen-deficient n=3 RP-member Sr3NdFe3O9-\delta and its topotactic derivatives”. Pelloquin D, Hadermann J, Giot M, Caignaert V, Michel C, Hervieu M, Raveau B, Chemistry of materials 16, 1715 (2004). http://doi.org/10.1021/cm030351n
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 9.466
Times cited: 24
DOI: 10.1021/cm030351n
|
“Many electron- and hole terms of molecular ions C60n\pm”. Nikolaev AV, Michel KH, Coupling In Chemistry And Physics 44, 305 (2003). http://doi.org/10.1016/S0065-3276(03)44019-7
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.196
Times cited: 1
DOI: 10.1016/S0065-3276(03)44019-7
|
“High resolution neutron and X-ray diffraction studies as a function of temperature and electric field of the ferroelectric phase transition of RDP”. Mattauch S, Heger G, Michel KH, Crystal research and technology 39, 1027 (2004). http://doi.org/10.1002/crat.200410289
Abstract: Neutron and high resolution X-ray diffraction investigations on perfect single crystals of RbH2PO4 (RDP), a hydrogen bonded ferroelectric of KDP type are reported. The results of crystal structure analysis from diffraction data, below and above the paraelectric – ferroelectric phase transition, support a disorder – order character Of [PO4H2](-)-groups. The tetragonal symmetry of the paraelectric phase with the double well potential of the hydrogen atoms obtained by diffraction, results simply from a time-space average of orthorhombic symmetry. According to the group – subgroup relation between the tetragonal space group 142d and the orthorhombic Fdd2 a short range order of ferroelectric clusters in the tetragonal phase is observed. With decreasing temperature the ferroelectric clusters increase and the long range interaction between their local polarisation vectors leads to the formation of lamellar ferroelectric domains with alternating polarisation directions at T-C = 147 K. From the high resolution X-ray data it is concluded that below T-C the ferroelastic strain in the (a,b)-plane leads to micro-angle grain boundaries at the domain walls. The tilt angle is enhanced by an applied electric field parallel to the ferroelectric axis. The resulting dislocations at the domain walls persist in the paraelectric phase leading to a memory effect for the arrangement of twin lamellae. With increased electric field the phase transition temperature T-C is decreased.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1
Times cited: 12
DOI: 10.1002/crat.200410289
|
“Safe use of metal-contaminated agricultural land by cultivation of energy maize (Zea mays)”. Van Slycken S, Witters N, Meers E, Peene A, Michels E, Adriaensen K, Ruttens A, Vangronsveld J, Du Laing G, Wierinck I, Van Dael M, Van Passel S, Tack FMG, Environmental Pollution 178, 375 (2013). http://doi.org/10.1016/J.ENVPOL.2013.03.032
Abstract: Production of food crops on trace element-contaminated agricultural lands in the Campine region (Belgium) can be problematic as legal threshold values for safe use of these crops can be exceeded. Conventional sanitation of vast areas is too expensive and alternatives need to be investigated. Zea mays on a trace element-contaminated soil in the region showed an average yield of 53 ± 10 Mg fresh or 20 ± 3 Mg dry biomass ha−1. Whole plant Cd concentrations complied with legal threshold values for animal feed. Moreover, threshold values for use in anaerobic digestion were met. Biogas production potential did not differ between maize grown on contaminated and non-contaminated soils. Results suggested favorable perspectives for farmers to generate non-food crops profitably, although effective soil cleaning would be very slow. This demonstrates that a valuable and sustainable alternative use can be generated for moderately contaminated soils on which conventional agriculture is impaired.
Keywords: A1 Journal article; Economics
Impact Factor: 5.099
Times cited: 30
DOI: 10.1016/J.ENVPOL.2013.03.032
|
“Electric quadrupole interactions and the γ-&alpha, phase transition in Ce: the role of conduction electrons”. Nikolaev AV, Michel KH, European physical journal : B : condensed matter and complex systems 17, 15 (2000). http://doi.org/10.1007/s100510070156
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.461
Times cited: 8
DOI: 10.1007/s100510070156
|
“Nanotube field and one-dimensional fluctuations of C60 molecules in carbon nanotubes”. Michel KH, Verberck B, Nikolaev AV, European physical journal : B : condensed matter and complex systems 48, 113 (2005). http://doi.org/10.1140/epjb/e2005-00378-9
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.461
Times cited: 25
DOI: 10.1140/epjb/e2005-00378-9
|
“Quantum charge density fluctuations and the γ-&alpha, phase transition in Ce”. Nikolaev AV, Michel KH, European physical journal : B : condensed matter and complex systems 9, 619 (1999). http://doi.org/10.1007/s100510050806
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.461
Times cited: 19
DOI: 10.1007/s100510050806
|
“Stabilisation of fcc cobalt layers by 0.4 nm thick manganese layers in Co/Mn superlattices”. Michel A, Pierron-Bohnes V, Jay JP, Panissod P, Lefebvre S, Bessière M, Fischer HE, Van Tendeloo G, European physical journal : B : condensed matter and complex systems 19, 225 (2001). http://doi.org/10.1007/s100510170331
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.461
Times cited: 8
DOI: 10.1007/s100510170331
|
“Theoretical model for the structural phase transition and the metal-insulator transition in polymerized KC60”. Verberck B, Nikolaev AV, Michel KH, Fullerenes, nanotubes, and carbon nanostructures
T2 –, 6th Biennial International Workshop on Fullerenes and Atomic Clusters, JUN 30-JUL 04, 2003, St Petersburg, RUSSIA 12, 243 (2004). http://doi.org/10.1081/FST-120027164
Abstract: The recently discovered structural phase transition in Polymerized KC60 at about 50K leads to a doubling of the unit cell volume and is accompanied by a metal-insulator transition. Here, we show that the ((a) over right arrow + (c) over right arrow, (b) over right arrow, (a) over right arrow – (c) over right arrow) superstructure results from orientational charge density waves along the polymer chains and correlated displacements of the K+ ions. The presented model can also account for the metal-insulator transition. The effect is specific for the space group Pmnn of KC60 and is absent in both Rb- and CsC60 (space group 12/m), in agreement with the present experimental knowledge of these compounds.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 1.35
DOI: 10.1081/FST-120027164
|
“Fullerene-cubane : X-ray scattering experiments and Monte Carlo simulations”. Verberck B, Heresanu V, Rouziere S, Cambedouzou J, Launois P, Kovats E, Pekker S, Vliegenthart GA, Michel KH, Gompper G, Fullerenes, nanotubes, and carbon nanostructures
T2 –, 8th Biennial International Workshop on Fullerenes and Atomic Clusters, (IWFAC 2007), JUL 02-06, 2007, St Petersburg, RUSSIA 16, 293 (2008). http://doi.org/10.1080/15363830802205830
Abstract: We report single-crystal X-ray diffuse scattering measurements on C-60.C8H8 fullerene-cubane showing that the C-60 molecules are orientationally disordered at 300 and 150K and get ordered at low temperatures. Monte Carlo simulations provide further insight in the orientational behavior of both C-60 and C8H8 molecules; low-temperature molecular orientations are predicted.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 1.35
Times cited: 6
DOI: 10.1080/15363830802205830
|
“The C60 molecules in (C60)N@SWCNT peapods: crystal field, intermolecular interactions and dynamics”. Verberck B, Michel KH, Nikolaev AV, Fullerenes, nanotubes, and carbon nanostructures 14, 171 (2006). http://doi.org/10.1080/15363830600663529
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.35
Times cited: 10
DOI: 10.1080/15363830600663529
|
“The isotope effect in hydrogen-bonded systems”. Bussmann-Holder A, Michel KH, International journal of modern physics: B: condensed matter physics, statistical physics, applied physics
T2 –, 1st International Conference on New Theories, Discoveries, and, Applications of Superconductors and Related Materials (New3SC-1), FEB 19-24, 19 12, 3406 (1998). http://doi.org/10.1142/S021797929800274X
Abstract: The giant isotope effect on the ferro- and antiferroelectric transition temperature upon deuteration of hydrogen-bonded systems is well known experimentally since various decades. Yet, theoretically only recently a microscopic understanding of this effect has been achieved which, specifically, took into account the geometry of the O ... H ... O bond. The implications of this modeling are multiple as numerous hydrogen-bonded organic systems show the same effects as ferro- and antiferroelectrics, i.e., cooperative proton tunneling at a well-defined temperature.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 0.736
DOI: 10.1142/S021797929800274X
|
“Nanotube field of C60 and C70 molecules in carbon nanotubes”. Verberck B, Michel KH, International journal of quantum chemistry 107, 2294 (2007). http://doi.org/10.1002/qua.21309
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.92
Times cited: 6
DOI: 10.1002/qua.21309
|
“Mécanismes de la non-stoechiométrie dans les nouveaux supraconducteurs à, haute Tc”. Hervieu M, Michel C, Martin C, Huvé, M, Van Tendeloo G, Maignan A, Pelloquin D, Goutenoire F, Raveau B, Journal de physique: 3: applied physics, materials science, fluids, plasma and instrumentation 4, 2057 (1994)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
|
“The ID21 X-ray and infrared microscopy beamline at the ESRF: status and recent applications to artistic materials”. Cotte M, Pouyet E, Salome M, Rivard C, De Nolf W, Castillo-Michel H, Fabris T, Monico L, Janssens K, Wang T, Sciau P, Verger L, Cormier L, Dargaud O, Brun E, Bugnazet D, Fayard B, Hesse B, del Real AEP, Veronesi G, Langlois J, Balcar N, Vandenberghe Y, Sole VA, Kieffer J, Barrett R, Cohen C, Cornu C, Baker R, Gagliardini E, Papillon E, Susini J, Journal of analytical atomic spectrometry 32, 477 (2017). http://doi.org/10.1039/C6JA00356G
Abstract: The ID21 beamline (European Synchrotron Radiation facility, France) is a multi micro-analytical platform combining X-ray and infrared micro-probes, for characterization of elements, species, molecular groups and crystalline structures in complex materials. Applications are mainly in the fields of cultural heritage, life science, environmental and earth sciences, materials sciences. Here, we first present the status of instruments: (i) the scanning micro-spectroscopy end-station, operating from 2.0 to 9.2 keV, under vacuum and offering cryo conditions, for the acquisition of 2D micro X-ray fluorescence (mu XRF) maps, single point micro X-ray Absorption Near Edge Structure (mu XANES) spectra and speciation maps with sub-micrometric resolution; (ii) the XANES full-field end-station, operating in the same vacuum and energy conditions, for the acquisition of hyper-spectral radiographs of thin concentrated samples, resulting in speciation maps with micrometric resolution and millimetric field of view; (iii) the scanning micro-X-ray diffraction (mu XRD)/mu XRF end-station, operating at 8.5 keV, in air, for the acquisition of 2D crystalline phase maps, with micrometric resolution; and (iv) the scanning infrared microscope, operating in the mid-infrared range for the acquisition of molecular maps and some structural maps with micrometric resolution. Recent hardware and software developments are presented, as well as new protocols for improved sample preparation of thin sections. Secondly, a review of recent applications for the study of cultural heritage is presented, illustrated by various examples: determination of the origin of the color in blue Chinese porcelains and in brown Sevres porcelains; detection of lead in ink on Herculaneum papyri; identification and degradation of modeling materials used by Auguste Rodin and of chrome yellow pigments used by Vincent van Gogh. Cryo capabilities are illustrated by the analysis of plants exposed to chromate solutions. These examples show the variety of materials analyzed, of questions tackled, and particularly the multiple advantages of the ID21 analytical platform for the analysis of ancient and artistic materials.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.379
Times cited: 39
DOI: 10.1039/C6JA00356G
|
“Elusive s-f intrasite interactions and double exchange in solids: ferromagnetic versus nonmagnetic ground state”. Nikolaev AV, Michel KH, Journal of experimental and theoretical physics 109, 286 (2009). http://doi.org/10.1134/S1063776109080147
Abstract: From the theory of many-electron states in atoms, we know that there exists a strong Coulomb repulsion, which results in the electronic term structure of atoms and is responsible for Hunds rules. By expanding the Coulomb on-site repulsion into a multipolar series, we derive this interaction and show that it is also present in solids as a correlation effect, which means that the interaction requires a multideterminant version of the Hartree-Fock method. Of particular interest is the case where this interaction couples states of localized ( f) and delocalized ( s) electrons. We show that the interaction is bilinear in the creation/annihilation operators for localized electrons and bilinear in the operators for conduction electrons. To study the coupling, we consider a simple model in the framework of an effective limited configuration interaction method with one localized f-electron and one itinerant s-electron per crystal site. The on-site multipole interaction between the f- and s-electrons is explicitly taken into account. It is shown that depending on the low-lying excitation spectrum imposed by the crystal electric field, the model can lead not only to ferromagnetism but also to a nonmagnetic state. The model is relevant for solids with localized and itinerant electron states.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.196
Times cited: 3
DOI: 10.1134/S1063776109080147
|