Home << 1 2 3 4 >>
List View
 | 
Citations
 | 
Details
   web
Records
Author Zhang, X.F.; Van Tendeloo, G.; Amelinckx, S.; Pelloquin, D.; Michel, C.; Hervieu, M.; Raveau, B.
Title Structural aspects of Bi2-xPbxSr3.5Cu2(CO3)O8-\delta for 0\leq x\leq0.75 : an electron-microscopy study Type A1 Journal article
Year 1994 Publication Journal of solid state chemistry Abbreviated Journal J Solid State Chem
Volume 113 Issue 2 Pages 327-344
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The structure and defect structure of Bi2-xPbxSr3.5Cu2 (CO3)O8-delta compounds with 0 less-than-or-equal-to x less-than-or-equal-to 0.75 are carefully investigated by electron diffraction and high-resolution electron microscopy. All compounds have an orthorhombic structure with a almost-equal-to b almost-equal-to 5.4 angstrom and c almost-equal-to 39.5 angstrom. The length of the b-axis decreases monotonically with increasing x. The space group for the basic structure is Abm2. The structure can be considered as an intergrowth of Bi2Sr2CuO6 lamellae with Sr2CuO2 (CO3) lamellae along the c-axis. CO3 groups behave as bridges connecting the CuO6 octahedra. In the x = 0 compound the carbon atoms are shifted away from their symmetry positions; the orientational ordering of the CO3 groups (or the carbon shift) in successive CO planes alternates along +b and -b. Typical Bi-type and Pb-type modulations are found along the b-axis up to a Pb content x = 0.5. Electron beam irradiation destroys the ordering of the CO3 groups and alters the modulated structure. (C) 1994 Academic press, inc.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos A1994PX18600016 Publication Date 2002-10-07
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4596; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.133 Times cited 8 Open Access
Notes Approved
Call Number (down) UA @ lucian @ c:irua:99810 Serial 3210
Permanent link to this record
 
 
Author Michel, K.H.; Verberck, B.
Title Theory of rigid-plane phonon modes in layered crystals Type A1 Journal article
Year 2012 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 85 Issue 9 Pages 094303-094303,11
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The lattice dynamics of low-frequency rigid-plane modes in metallic (graphene multilayers, GML) and in insulating (hexagonal boron-nitride multilayers, BNML) layered crystals is investigated. The frequencies of shearing and compression (stretching) modes depend on the layer number N and are presented in the form of fan diagrams. The results for GML and BNML are very similar. In both cases, only the interactions (van der Waals and Coulomb) between nearest-neighbor planes are effective, while the interactions between more distant planes are screened. A comparison with recent Raman scattering results on low-frequency shear modes in GML [Tan et al., Nat. Mater., in press, doi: 10.1038/nmat3245, (2012)] is made. Relations with the low-lying rigid-plane phonon dispersions in the bulk materials are established. Master curves, which connect the fan diagram frequencies for any given N, are derived. Static and dynamic thermal correlation functions for rigid-layer shear and compression modes are calculated. The results might be of use for the interpretation of friction force experiments on multilayer crystals.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000301646000006 Publication Date 2012-03-19
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 38 Open Access
Notes ; The authors are indebted to J. Maultzsch for bringing Ref. 20 to their attention. They thank D. Lamoen, F.M. Peeters, B. Trauzettel, and C. Van Haesendonck for useful discussions. This work has been financially supported by the Research Foundation Flanders (FWO). ; Approved Most recent IF: 3.836; 2012 IF: 3.767
Call Number (down) UA @ lucian @ c:irua:97787 Serial 3619
Permanent link to this record
 
 
Author Michel, K.H.; Copley, J.R.D.; Neumann, D.A.
Title Microscopic theory of orientational disorder and the orientational phase transition in solid C60 Type A1 Journal article
Year 1992 Publication Physical review letters Abbreviated Journal Phys Rev Lett
Volume 68 Issue 19 Pages 2929-2932
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We have developed a microscopic theory which describes the orientational dynamics of C60 molecules in the face-centered-cubic phase of C60 fullerite. The molecular interaction potential and the crystal-field potential are formulated in terms of symmetry-adapted rotator functions. The phase transition to the Pa3BAR structure is driven by an active multipolar mode of T2g symmetry belonging to the l = 10 manifold. The Birman criterion is satisfied. The transition is found to be of first order.
Address
Corporate Author Thesis
Publisher Place of Publication New York, N.Y. Editor
Language Wos A1992HT64800019 Publication Date 2002-07-27
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0031-9007; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 7.512 Times cited 94 Open Access
Notes Approved
Call Number (down) UA @ lucian @ c:irua:95492 Serial 2032
Permanent link to this record
 
 
Author Hervieu; Van Tendeloo, G.; Michel; Pelloquin; Raveau
Title Mixed layers in copper based superconducting materials Type A1 Journal article
Year 1996 Publication Microscopy, microanalysis, microstructures Abbreviated Journal
Volume 7 Issue 2 Pages 107-141
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Recently discovered series of high Tc superconductors, characterized by the existence of two types of cations within the same layer, are presented. The first family concerns the mercury based cuprates, Hg(1-x)M(x)A(2)Ca(m-1)Cu(m)O(2m+2+delta), with A = Ba and/or Sr, which exhibit structures closely related to that of the thallium cuprates TlBa2Cam-1CumO2m+3. They differ from the thallium cuprates by a high oxygen deficiency at the level of the mercury layer. It is shown that cations such as M = Cu, Pb, Tl, Bi, Ce, Pr, Cr, V, Mo, W, Ti, Sr, Ca,... can partially substitute for mercury ions, stabilizing the structures. The cationic composition of the layer depends indeed on the nature of the M cation but also on that of the alkaline earth A. For given A and M cations, the a: value remains unchanged even when the number of copper layers varies. M and Hg cations are either statistically distributed over the same site or ordered. Different types of ordering have been detected. Another way of generating mixed layers is to shear periodically the structure, leading to the formation of the so called ''collapsed phase''. In the collapsed bismuth cuprates, bismuth and copper segments, a few octahedra long, alternate in strongly waving layers. In the collapsed oxycarbonates, carbonate groups and M cations are ordered within the intermediate layer so that they can be simply described from a partial and ordered substitution of carbon for Hg,TI, Bi and other M cations building the intermediate layer. The oxycarbonitrates (Y1-xCax)(n)Ba2nCu3n-1(C,N)O3O7n-3 can also be described as an ordered substitution of carbon for copper in the 123 matrix. The different families of superconducting materials which are generated by such mechanisms are described as well as the way the different species are distributed within the mixed layers. Their influence on the physical properties are discussed.
Address
Corporate Author Thesis
Publisher Place of Publication Ivry Editor
Language Wos A1996VA22000004 Publication Date 2003-08-13
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1154-2799; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor Times cited 2 Open Access
Notes Approved no
Call Number (down) UA @ lucian @ c:irua:95287 Serial 2088
Permanent link to this record
 
 
Author Verberck, B.; Nikolaev, A.V.; Michel, K.H.
Title Theoretical model for the structural phase transition at the metal-insulator transition in polymerized KC60 Type A1 Journal article
Year 2002 Publication Physical Review B Abbreviated Journal Phys Rev B
Volume 66 Issue 16 Pages 165425-165425,14
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The recently discovered structural transition in polymerized KC60 at about 50 K results in a doubling of the unit cell volume and accompanies the 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 small orientational charge density waves along the polymer chains and concomitant displacements of the surrounding K+ ions. The effect is specific for the space group Pmnn of KC60 and is absent in RbC60 and CsC60 (space group I2/m). The mechanism is relevant for the metal-insulator transition.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000179286400135 Publication Date 2002-10-30
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829;1095-3795; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 10 Open Access
Notes Approved Most recent IF: 3.836; 2002 IF: NA
Call Number (down) UA @ lucian @ c:irua:94907 Serial 3608
Permanent link to this record
 
 
Author Nikolaev, A.V.; Michel, K.H.
Title Symmetry lowering at the structural phase transitions in NpO2 and UO2 Type A1 Journal article
Year 2003 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 68 Issue 5 Pages 054112-054112,7
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The structural phase transitions with electric-quadrupole long-range order in NpO2 (Fm (3) over barm-->Pn (3) over barm) and UO2 (Fm (3) over barm-->Pa (3) over bar) are analyzed from a group theoretical point of view. In both cases, the symmetry lowering involves three quadrupolar components belonging to the irreducible representation T-2g (Gamma(5)) of O-h and condensing in a triple-q structure at the X point of the Brillouin zone. The Pa (3) over bar structure is close to Pn (3) over barm, but allows for oxygen displacements. The Pa (3) over bar ordering leads to an effective electrostatic attraction between electronic quadrupoles while the Pn (3) over barm ordering results in a repulsion between them. It is concluded that the Pn (3) over barm structure can be stabilized only through some additional process such as strengthening of the chemical bonding between Np and O. We also derive the relevant structure-factor amplitudes for Pn (3) over barm and Pa (3) over bar, and the effect of domains on resonant x-ray scattering experiments.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000185240100038 Publication Date 2003-08-29
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829;1095-3795; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 15 Open Access
Notes Approved Most recent IF: 3.836; 2003 IF: NA
Call Number (down) UA @ lucian @ c:irua:94847 Serial 3405
Permanent link to this record
 
 
Author Verberck, B.; Nikolaev, A.V.; Michel, K.H.
Title Orientational charge density waves and the metal-insulator transition in polymerized KC60 Type A1 Journal article
Year 2004 Publication AIP conference proceedings Abbreviated Journal
Volume 723 Issue Pages 339-342
Keywords A1 Journal article; Condensed Matter Theory (CMT)
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.
Address
Corporate Author Thesis
Publisher Place of Publication New York Editor
Language Wos Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0094-243x ISBN Additional Links UA library record; WoS full record;
Impact Factor Times cited Open Access
Notes Approved Most recent IF: NA
Call Number (down) UA @ lucian @ c:irua:94831 Serial 2513
Permanent link to this record
 
 
Author Mattauch, S.; Heger, G.; Michel, K.H.
Title High resolution neutron and X-ray diffraction studies as a function of temperature and electric field of the ferroelectric phase transition of RDP Type A1 Journal article
Year 2004 Publication Crystal research and technology Abbreviated Journal Cryst Res Technol
Volume 39 Issue 12 Pages 1027-1054
Keywords A1 Journal article; Condensed Matter Theory (CMT)
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.
Address
Corporate Author Thesis
Publisher Place of Publication Berlin Editor
Language Wos 000225681100001 Publication Date 2004-11-12
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0232-1300;1521-4079; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1 Times cited 12 Open Access
Notes Approved Most recent IF: 1; 2004 IF: 0.770
Call Number (down) UA @ lucian @ c:irua:94785 Serial 1459
Permanent link to this record
 
 
Author Michel, K.H.; Verberck, B.; Nikolaev, A.
Title Mercator maps of orientations of a C60 molecule in single-walled nanotubes with distinct radii Type A1 Journal article
Year 2005 Publication AIP conference proceedings Abbreviated Journal
Volume 786 Issue Pages 69-72
Keywords A1 Journal article; Condensed Matter Theory (CMT)
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.
Address
Corporate Author Thesis
Publisher Amer inst physics Place of Publication Melville Editor
Language Wos Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0094-243x ISBN Additional Links UA library record; WoS full record;
Impact Factor Times cited Open Access
Notes Approved Most recent IF: NA
Call Number (down) UA @ lucian @ c:irua:94738 Serial 1993
Permanent link to this record
 
 
Author Michel, K.H.; Verberck, B.; Nikolaev, A.V.
Title Anisotropic packing and one-dimensional fluctuations of C60 molecules in carbon nanotubes Type A1 Journal article
Year 2005 Publication Physical review letters Abbreviated Journal Phys Rev Lett
Volume 95 Issue 18 Pages 185506-185506,4
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The confinement of a C-60 molecule encapsulated in a cylindrical nanotube depends on the tube radius. In small tubes with radius R-T less than or similar to 7 A, a fivefold axis of the molecule coincides with the tube axis. The interaction between C-60 molecules in the nanotube is then described by a O-2-rotor model on a 1D liquid chain with coupling between orientational and displacive correlations. This coupling leads to chain contraction. The structure factor of the 1D liquid is derived. In tubes with a larger radius the molecular centers of mass are displaced off the tube axis. The distinction of two groups of peapods with on- and off-axis molecules suggests an explanation of the apparent splitting of A(g) modes of C-60 in nanotubes measured by resonant Raman scattering.
Address
Corporate Author Thesis
Publisher Place of Publication New York, N.Y. Editor
Language Wos 000232887400041 Publication Date 2005-10-28
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0031-9007;1079-7114; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 8.462 Times cited 40 Open Access
Notes Approved Most recent IF: 8.462; 2005 IF: 7.489
Call Number (down) UA @ lucian @ c:irua:94717 Serial 127
Permanent link to this record
 
 
Author Michel, K.H.; Verberck, B.
Title Theory of phonon dispersions and piezoelectricity in multilayers of hexagonal boron-nitride Type A1 Journal article
Year 2011 Publication Physica status solidi: B: basic research Abbreviated Journal Phys Status Solidi B
Volume 248 Issue 11 Pages 2720-2723
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Taking into account covalent, Coulomb and van der Waals interactions, we construct the dynamical matrix and calculate the phonon dispersion relations for multilayer crystals of hexagonal boron-nitride. Coulomb interactions account for a strong overbending of optical phonons. Applying and extending Born's long-wave theory to the case of multilayer crystals, we calculate the piezoelectric stress constant equation image as a function of the number of layers equation image. In agreement with group theory, we find that equation image for equation image even; for an uneven number equation image of layers we obtain equation image, i.e. the piezoelectric constant decreases as equation image.
Address
Corporate Author Thesis
Publisher Place of Publication Berlin Editor
Language Wos 000297517100069 Publication Date 2011-10-18
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0370-1972; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.674 Times cited 13 Open Access
Notes ; Discussions with G. Heger, B. Partoens and F. M. Peeters are gratefully acknowledged. This work has been supported by the Flemish Science Foundation (FWO-Vl) and the Bijzonder Onderzoeksfonds, Universiteit Antwerpen (BOF-UA). ; Approved Most recent IF: 1.674; 2011 IF: 1.316
Call Number (down) UA @ lucian @ c:irua:94034 Serial 3618
Permanent link to this record
 
 
Author Bostoen, C.; Michel, K.H.
Title Dynamics of a quadrupolar glass Type A1 Journal article
Year 1991 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 43 Issue Pages 4415-4422
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos A1991EX92100073 Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121; 0163-1829 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.736 Times cited 33 Open Access
Notes Approved no
Call Number (down) UA @ lucian @ c:irua:939 Serial 773
Permanent link to this record
 
 
Author Lamoen, D.; Michel, K.H.
Title Crystal field, orientational order, and lattice contraction in solid C60 Type A1 Journal article
Year 1994 Publication The journal of chemical physics Abbreviated Journal J Chem Phys
Volume 101 Issue Pages 1435-1443
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract A model of the intermolecular potential in solid C-60, which is based on Born-Mayer repulsions, van der Waals attractions, and electrostatic multipoles, is presented. The potential is expanded in terms of multipolar rotator functions. The orientation-orientation interaction and the crystal field are calculated. The orientational phase transition to the Pa3 phase is studied with the methods of statistical mechanics. The discontinuity of the order parameter at the transition and the temperature evolution of the order parameter are calculated. The lattice contraction at the phase transition is evaluated. The influence of the lattice contraction on the crystal field and on the orientational order is studied.
Address
Corporate Author Thesis
Publisher Place of Publication New York, N.Y. Editor
Language Wos A1994NW97900058 Publication Date 2002-07-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-9606; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.952 Times cited 39 Open Access
Notes Approved CHEMISTRY, PHYSICAL 54/144 Q2 # PHYSICS, ATOMIC, MOLECULAR & CHEMICAL 9/35 Q2 #
Call Number (down) UA @ lucian @ c:irua:9361 Serial 554
Permanent link to this record
 
 
Author Lynden-Bell, R.M.; Michel, K.H.
Title Translation-rotation coupling, phase transitions and elastic phenomena in orientationally disordered crystals Type A1 Journal article
Year 1994 Publication Reviews of modern physics Abbreviated Journal Rev Mod Phys
Volume 66 Issue Pages 721-762
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication New York Editor
Language Wos A1994PG73600003 Publication Date 2002-09-05
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0034-6861;1539-0756; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 29.604 Times cited 128 Open Access
Notes Approved no
Call Number (down) UA @ lucian @ c:irua:9359 Serial 3702
Permanent link to this record
 
 
Author Lamoen, D.; Michel, K.H.
Title Molecular structure, crystal field and orientational order in solid C60 Type H1 Book chapter
Year 1994 Publication Abbreviated Journal
Volume Issue Pages 183-202
Keywords H1 Book chapter; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication s.l. Editor
Language Wos A1994BE86T00011 Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN 0-7923-3109-5 Additional Links UA library record; WoS full record;
Impact Factor Times cited Open Access
Notes Approved
Call Number (down) UA @ lucian @ c:irua:9355 Serial 2186
Permanent link to this record
 
 
Author Michel, K.H.; Verberck, B.
Title Phonon dispersions and piezoelectricity in bulk and multilayers of hexagonal boron nitride Type A1 Journal article
Year 2011 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 83 Issue 11 Pages 115328-115328,14
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract A unified theory of phonon dispersions and piezoelectricity in bulk and multilayers of hexagonal boron nitride (h-BN) is derived. The dynamical matrix is calculated on the basis of an empirical force constant model of intralayer valence and interlayer van der Waals interactions. Coulomb interactions are calculated by Ewalds method, adapted for the three-dimensional (3D) and the multilayer case. The deformation of the ionic charge distribution with long-wave lattice displacements is taken into account. Special attention is devoted to the nonanalytic long-range Coulomb contribution to the dynamical matrix which is different for the 3D crystal and the multilayer case. Consequently there is a splitting of the transverse optical (TO) and longitudinal optical (LO) phonon branches of E1u symmetry and a discontinuity of the A2u branch at the Γ point in 3D h-BN. No such splitting and discontinuity at Γ are present in multilayer crystals with a finite number N of layers. There a diverging bundle of N overbending optical phonon branches emerges from Γ. Borns long-wave theory is applied and extended for the study of piezoelectricity in layered crystals. While 3D h-BN and h-BN multilayers with an even number of layers (symmetry D6h) are not piezoelectric, multilayers with an uneven number of Nu layers (symmetry D3h) are piezoelectric; the piezoelectric coefficient e1,11 is inversely proportional to Nu.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000288783700005 Publication Date 2011-03-24
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 82 Open Access
Notes ; Discussions with G. Heger, B. Partoens, and F. M. Peeters are gratefully acknowledged. This work has been supported by the Flemish Science Foundation (FWO-V1) and the Bijzonder Onderzoeksfonds, Universiteit Antwerpen (BOF-UA). ; Approved Most recent IF: 3.836; 2011 IF: 3.691
Call Number (down) UA @ lucian @ c:irua:89602 Serial 2603
Permanent link to this record
 
 
Author Tsvyashchenko, A.V.; Nikolaev, A.V.; Velichkov, A.I.; Salamatin, A.V.; Fomicheva, L.N.; Ryasny, G.K.; Sorokin, A.A.; Kochetov, O.I.; Budzynski, M.; Michel, K.H.
Title Lowering of the spatial symmetry at the gamma ->alpha phase transition in cerium Type A1 Journal article
Year 2010 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 82 Issue 9 Pages 1-4
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Using time-differential perturbed angular correlation spectroscopy we have measured the electric field gradient (EFG) at 111Cd probe nuclei in solid Ce in a pressure range up to 8 GPa. Covering various allotropic phases of Ce, we find that the value of the EFG in the cubic α phase is almost four times larger than in the cubic γ phase and close to values in the noncubic phases α′ and α″. These results together with the differences in time modulation of the spectra are interpreted as evidence for quadrupolar electronic charge-density ordering and symmetry lowering at the γ→α transition while the lattice remains face-centered cubic
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000282004400001 Publication Date 2010-09-16
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 11 Open Access
Notes ; This work is supported by the Program of the Presidium of the Russian Academy of Sciences “Physics of Strongly Compressed Matter.” We are grateful to S. M. Stishov, B. Verberck, A. N. Grum-Grzhimailo, V. B. Brudanin and G. Heger for support of this work and discussion of the results. ; Approved Most recent IF: 3.836; 2010 IF: 3.774
Call Number (down) UA @ lucian @ c:irua:85464 Serial 1854
Permanent link to this record
 
 
Author Michel, K.H.; Verberck, B.
Title Theoretical phonon dispersions in monolayers and multilayers of hexagonal boron-nitride Type A1 Journal article
Year 2009 Publication Physica status solidi: B: basic research Abbreviated Journal Phys Status Solidi B
Volume 246 Issue 11/12 Pages 2802-2805
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Starting from an empirical force constant model of valence interactions and calculating by Ewald's method the electrostatic force constants, we derive the dynamical matrix for a monolayer and for multilayer systems of hexagonal boron nitride (h-BN). Solution of the secular problem leads to the corresponding phonon dispersion relations. The interplay between valence forces and Coulomb forces is discussed. A comparison with previous results on graphene and graphene multilayers is made. Our spectra on the h-BN monolayer are rather similar to previous ab initio theory results. Comparison is also made with Raman and infrared experimental results.
Address
Corporate Author Thesis
Publisher Place of Publication Berlin Editor
Language Wos 000272904100091 Publication Date 2009-11-12
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0370-1972; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.674 Times cited 10 Open Access
Notes Approved Most recent IF: 1.674; 2009 IF: 1.150
Call Number (down) UA @ lucian @ c:irua:80673 Serial 3609
Permanent link to this record
 
 
Author Michel, K.H.; Verberck, B.
Title Theory of elastic and piezoelectric effects in two-dimensional hexagonal boron nitride Type A1 Journal article
Year 2009 Publication Physical review : B : solid state Abbreviated Journal Phys Rev B
Volume 80 Issue 22 Pages 224301,1-224301,10
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Starting from an empirical force constant model of valence interactions and calculating by Ewalds method the ion-ion force constants, we derive the dynamical matrix for a monolayer crystal of hexagonal boron nitride (h-BN). The phonon dispersion relations are calculated. The interplay between valence and Coulomb forces is discussed. It is shown by analytical methods that the longitudinal and the transverse optical (LO and TO) phonon branches for in-plane motion are degenerate at the Γ point of the Brillouin zone. Away from Γ, the LO branch exhibits pronounced overbending. It is found that the nonanalytic Coulomb contribution to the dynamical matrix causes a linear increase of the LO branch with increasing wave vector starting at Γ. This effect is general for two-dimensional (2D) ionic crystals. Performing a long-wavelength expansion of the dynamical matrix, we use Borns perturbation method to calculate the elastic constants (tension coefficients). Since the crystal is noncentrosymmetric, internal displacements due to relative shifts between the two sublattices (B and N) contribute to the elastic constants. These internal displacements are responsible for piezoelectric and dielectric phenomena. The piezoelectric stress constant and the dielectric susceptibility of 2D h-BN are calculated.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000273228500045 Publication Date 2009-12-21
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 96 Open Access
Notes Approved Most recent IF: 3.836; 2009 IF: 3.475
Call Number (down) UA @ lucian @ c:irua:80576 Serial 3616
Permanent link to this record
 
 
Author Nikolaev, A.V.; Michel, K.H.
Title Elusive s-f intrasite interactions and double exchange in solids: ferromagnetic versus nonmagnetic ground state Type A1 Journal article
Year 2009 Publication Journal of experimental and theoretical physics Abbreviated Journal J Exp Theor Phys+
Volume 109 Issue 2 Pages 286-292
Keywords A1 Journal article; Condensed Matter Theory (CMT)
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.
Address
Corporate Author Thesis
Publisher Place of Publication Woodbury, N.Y. Editor
Language Wos 000270506500014 Publication Date 2009-09-18
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1063-7761;1090-6509; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.196 Times cited 3 Open Access
Notes Approved Most recent IF: 1.196; 2009 IF: 0.871
Call Number (down) UA @ lucian @ c:irua:79163 Serial 1027
Permanent link to this record
 
 
Author Michel, K.H.; Verberck, B.
Title Theory of the evolution of phonon spectra and elastic constants from graphene to graphite Type A1 Journal article
Year 2008 Publication Physical review : B : solid state Abbreviated Journal Phys Rev B
Volume 78 Issue 8 Pages 085424,1-085424,17
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We present a unified theory of the phonon dispersions and elastic properties of graphene, graphite, and graphene multilayer systems. Starting from a fifth-nearest-neighbor force-constant model derived from full in-plane phonon dispersions of graphite [Mohr et al., Phys. Rev. B 76, 035439 (2007)], we use Born's long-wave method to calculate the tension and bending coefficients of graphene. Extending the model by interplanar interactions, we study the phonon dispersions and the elastic constants of graphite, and the phonon spectra of graphene multilayers. We find that the inner displacement terms due to sublattice shifts between inequivalent C atoms are quantitatively important in determining the elastomechanical properties of graphene and of graphite. The overall agreement between theory and experiment is very satisfactory. We investigate the evolution from graphene to graphite by studying the increase in the rigid plane optical mode as a function of the number of layers N. At N=10 the graphite value B2g1127 cm−1 is attained within a few percent.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000259406900106 Publication Date 2008-08-21
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1098-0121;1550-235X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 72 Open Access
Notes Approved Most recent IF: 3.836; 2008 IF: 3.322
Call Number (down) UA @ lucian @ c:irua:76527 Serial 3622
Permanent link to this record
 
 
Author Michel, K.H.; Verberck, B.
Title Theory of the elastic constants of graphite and graphene Type A1 Journal article
Year 2008 Publication Physica status solidi: B: basic research Abbreviated Journal Phys Status Solidi B
Volume 245 Issue 10 Pages 2177-2180
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Born's long wave method is used to study the elastic properties of graphite and graphene. Starting from an empirical force constant model derived from full inplane phonon dispersions of graphite [Mohr et al., Phys. Rev. B 76, 035439 (2007)] we calculate the tension coefficients of graphene. Extending the model by interplanar interactions, we calculate the elastic constants of graphite. The agreement of our theoretical values with inelastic x-ray scattering results on elastic constants of graphite [Bosak et al., Phys. Rev. B 75, 153408 (2007)] is very satisfactory.
Address
Corporate Author Thesis
Publisher Place of Publication Berlin Editor
Language Wos 000260581800066 Publication Date 2008-08-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0370-1972; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.674 Times cited 47 Open Access
Notes Approved Most recent IF: 1.674; 2008 IF: 1.166
Call Number (down) UA @ lucian @ c:irua:75660 Serial 3621
Permanent link to this record
 
 
Author Martin, C.; Huvé, M.; Van Tendeloo, G.; Maignan, A.; Michel, C.; Hervieu, M.; Raveau, B.
Title A mercury based superconducting cuprate, intergrowth of the 2201 and 1201 structures Tl2HgBa4Cu2O10+y Type A1 Journal article
Year 1993 Publication Physica: C : superconductivity Abbreviated Journal Physica C
Volume 212 Issue Pages 274-278
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos A1993LN08500004 Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4534 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 0.942 Times cited 21 Open Access
Notes Approved no
Call Number (down) UA @ lucian @ c:irua:7500 Serial 1996
Permanent link to this record
 
 
Author Pelloquin, D.; Michel, C.; Van Tendeloo, G.; Maignan, A.; Hervieu, M.; Raveau, B.
Title A new “1201” mercury cuprate: the 27K-superconductor HG0.5Bi0.5Sr2-xLaxCuO5-\delta Type A1 Journal article
Year 1993 Publication Physica: C : superconductivity Abbreviated Journal Physica C
Volume 214 Issue Pages 87-92
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos A1993LW02700011 Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4534 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 0.942 Times cited 62 Open Access
Notes Approved CHEMISTRY, PHYSICAL 77/144 Q3 # MATHEMATICS, INTERDISCIPLINARY 19/101 Q1 # PHYSICS, ATOMIC, MOLECULAR & CHEMICAL 17/35 Q2 #
Call Number (down) UA @ lucian @ c:irua:6849 Serial 2301
Permanent link to this record
 
 
Author Maignan, A.; Michel, C.; Van Tendeloo, G.; Hervieu, M.; Raveau, B.
Title Superconductivity up to 110K in the 1212-Hg based cuprate Nd1-xCaxBa2Hg1-xCu2+xO6+y Type A1 Journal article
Year 1993 Publication Physica: C : superconductivity Abbreviated Journal Physica C
Volume 216 Issue Pages 1-5
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos A1993MD16100001 Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4534 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 0.942 Times cited 32 Open Access
Notes Approved PHYSICS, APPLIED 28/145 Q1 #
Call Number (down) UA @ lucian @ c:irua:6848 Serial 3375
Permanent link to this record
 
 
Author Maignan, A.; Van Tendeloo, G.; Hervieu, M.; Michel, C.; Raveau, B.
Title A new “1212” mercury-based 90K superconductor: (Hg1-xMx)O6+y Type A1 Journal article
Year 1993 Publication Physica: C : superconductivity Abbreviated Journal Physica C
Volume 212 Issue Pages 239-244
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos A1993LL33900033 Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4534 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 0.942 Times cited 36 Open Access
Notes Approved CHEMISTRY, PHYSICAL 77/144 Q3 # MATHEMATICS, INTERDISCIPLINARY 19/101 Q1 # PHYSICS, ATOMIC, MOLECULAR & CHEMICAL 17/35 Q2 #
Call Number (down) UA @ lucian @ c:irua:6846 Serial 2302
Permanent link to this record
 
 
Author Hervieu, M.; Van Tendeloo, G.; Maignan, A.; Michel, C.; Goutenoire, F.; Raveau, B.
Title New 1212-type superconductors with a Tc up to 85K in the system Hg-Pr-Sr-Ca-Cu-O Type A1 Journal article
Year 1993 Publication Physica: C : superconductivity Abbreviated Journal Physica C
Volume 216 Issue Pages 264-272
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos A1993ME74800005 Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4534 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 0.942 Times cited 66 Open Access
Notes Approved CHEMISTRY, PHYSICAL 77/144 Q3 # MATHEMATICS, INTERDISCIPLINARY 19/101 Q1 # PHYSICS, ATOMIC, MOLECULAR & CHEMICAL 17/35 Q2 #
Call Number (down) UA @ lucian @ c:irua:6845 Serial 2303
Permanent link to this record
 
 
Author Pelloquin, D.; Hervieu, M.; Michel, C.; Van Tendeloo, G.; Maignan, A.; Raveau, B.
Title A 94K Hg-based superconductor with a “1212” structure HG0.5Bi0.5Sr2Ca1-xRxCu2O6+\delta (R=ND,Y,Pr) Type A1 Journal article
Year 1993 Publication Physica: C : superconductivity Abbreviated Journal Physica C
Volume 216 Issue Pages 257-263
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos A1993ME74800004 Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4534 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 0.942 Times cited 62 Open Access
Notes Approved no
Call Number (down) UA @ lucian @ c:irua:6844 Serial 21
Permanent link to this record
 
 
Author Goutenoire, F.; Daniel, P.; Hervieu, M.; Van Tendeloo, G.; Michel, C.; Maignan, A.; Raveau, B.
Title New mercury-based superconductors with the “1201” structure Hg0.4Pr0.6Sr2-xPrxCuO4+\delta and Hg0.3Pb0.7Sr2-xLaxCuO4+\delta Type A1 Journal article
Year 1993 Publication Physica: C : superconductivity Abbreviated Journal Physica C
Volume 216 Issue Pages 243-249
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos A1993ME74800002 Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0921-4534 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 0.942 Times cited 50 Open Access
Notes Approved
Call Number (down) UA @ lucian @ c:irua:6843 Serial 2322
Permanent link to this record
 
 
Author Verberck, B.; Michel, K.H.
Title Anisotropic packing of C-70 molecules in carbon nanotubes Type A1 Journal article
Year 2007 Publication Physica status solidi B-basic solid state physics Abbreviated Journal Phys Status Solidi B
Volume 244 Issue 11 Pages 4279-4282
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000251355800092 Publication Date 2007-10-19
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0370-1972;1521-3951; ISBN Additional Links UA library record; WoS full record
Impact Factor 1.674 Times cited Open Access
Notes Approved Most recent IF: 1.674; 2007 IF: 1.071
Call Number (down) UA @ lucian @ c:irua:67350 Serial 128
Permanent link to this record