“Phase transitions in AC60 (A=Rb, Cs) fullerides”. Nikolaev AV, Prassides K, Michel KH, Recent advances in the chemistry and physics of fullerenes and related materials 5, 450 (1997)
Keywords: A3 Journal article; Condensed Matter Theory (CMT)
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“Orientational mode coupling, diffuse scattering, and the order-disorder phase transition in solid C60”. Michel KH, Copley JRD, Zeitschrift für Physik: B: condensed matter and quanta 103, 369 (1997)
Keywords: A3 Journal article; Condensed Matter Theory (CMT)
Times cited: 21
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“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)
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“Mixed layers in copper based superconducting materials”. Hervieu, Van Tendeloo G, Michel, Pelloquin, Raveau, Microscopy, microanalysis, microstructures 7, 107 (1996). http://doi.org/10.1051/mmm:1996109
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.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 2
DOI: 10.1051/mmm:1996109
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“Microscopic theory of the rhombohedral phase and transition to the monoclinic phase of solid C70”. Nikolaev AV, Michel KH, Physical review : B : condensed matter and materials physics 54, 12733 (1996). http://doi.org/10.1103/PhysRevB.54.12733
Abstract: Starting from a model of microscopic interactions between C-70 molecules, we have developed a theory which describes the orientational dynamics and its coupling to lattice displacements in the rhombohedral phase of C-70 fullerite. The Landau free energy is calculated. We obtain a first-order phase transition to a monoclinic structure with the space group P2(1)/m. The transition is driven by the condensation of orientational quadrupoles at the F point of the Brillouin zone of the rhombohedral lattice. We find no evidence that the monoclinic structure is connected with the freezing in of orientations around the fivefold molecular axis. We calculate the lattice strains that are associated with the transition to the monoclinic structure. The theory is compared with a range of experimental data on the phase transition.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.736
Times cited: 5
DOI: 10.1103/PhysRevB.54.12733
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“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)
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“Structural investigations of recently discovered high Tc superconductors”. Van Tendeloo G, Krekels T, Amelinckx S, Babu TGN, Greaves C, Hervieu M, Michel C, Raveau B, Microscopy research and technique 30, 102 (1995). http://doi.org/10.1002/jemt.1070300203
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.154
Times cited: 4
DOI: 10.1002/jemt.1070300203
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“A new cuprate with mercury bilayers : the “2222&rdquo, oxide Hg2-xMxBa2Pr2Cu2O10-\delta (M= Cu,Pr)”. Huve M, Martin C, Maignan A, Michel C, Van Tendeloo G, Hervieu M, Raveau B, Journal of solid state chemistry 114, 230 (1995). http://doi.org/10.1006/jssc.1995.1033
Abstract: A ''2222'' cuprate with mercury bilayers (Hg1.5Cu0.2Pr0.3)Ba2Pr2Cu2O10-delta, has been synthesized for the first time. It crystallizes in the P4/nmm space group with a = 3.9072(1) Angstrom and c = 17.219(1) Angstrom. The powder XRD and HREM studies of this new cuprate show that its structure consists of an intergrowth of double pyramidal (oxygen-deficient perovskite) copper layers, with double fluorite-type layers and distorted triple rock salt layers (mercury bilayers). The structure of this phase can be deduced from that of the ''2212'' mercury cuprate (Hg1.5Cu0.2Pr0.3)Ba2PrCu2O8-delta by the introduction of one additional [PrO2]infinity fluorite layer. The regular stacking of the metallic layer and the uniform cationic distribution in the mercury bilayers are remarkable features of this cuprate. The stabilization of the mercury bilayers by praseodymium and the absence of superconductivity are discussed. (C) 1995 Academic Press, Inc.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.133
Times cited: 6
DOI: 10.1006/jssc.1995.1033
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“Synthesis and characterization of mercury based “1222&rdquo, cuprates (Hg1-xMx)(Sr,Ba)2Pr2Cu2O9-\delta (M = Pr, Pb, Bi, Tl)”. Hervieu M, Van Tendeloo G, Michel C, Martin C, Maignan A, Raveau B, Journal of solid state chemistry 115, 525 (1995). http://doi.org/10.1006/jssc.1995.1169
Abstract: Five new layered cuprates, with a 1222-type structure, have been synthesized according to the formula (Hg(1-x)M(x))(Sr,Ba)(2) Pr2Cu2O9-delta with M = Pr, Pb, Pi, and Tl. They crystallize in a tetragonal cell with a approximate to a(p) and c approximate to 29.5 Angstrom; their structure consists in a triple intergrowth of oxygen-deficient perovskite, rock-salt-and fluorite-type layers. They are characterized by a mixed [Hg(1-x)M(x)O(1-delta)] layer in the rock-sail-type slice. The ED and HREM studies show that Tl, Bi, and Pb are statistically distributed in the mixed [Hg(1-x)M(x)O(1-delta)] layer, contrary to Pr which involves an ordering phenomenon along a. Different stacking defects are observed and discussed as well as the cleavage mode of the crystals. (C) 1995 Academic Press, Inc.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.133
Times cited: 5
DOI: 10.1006/jssc.1995.1169
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“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
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“Microscopic theory of orientational disorder and lattice instability in solid C70”. Callebaut AK, Michel KH, Physical review : B : condensed matter and materials physics 52, 15279 (1995). http://doi.org/10.1103/PhysRevB.52.15279
Abstract: We have developed a microscopic theory which describes the orientational dynamics of C-70 molecules and its coupling to lattice displacements in the face-centered-cubic phase of C-70 fullerite. The single-molecule orientational density distribution in the disordered phase is calculated. The ferroelastic transition to the rhombohedral phase is investigated. The discontinuity of the orientational order parameter at the phase transition is calculated. It is found that the transition leads to a stretching of the primitive unit cell along a [111] cubic direction. A softening of the elastic constant c(44) at the transition is predicted.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.736
Times cited: 20
DOI: 10.1103/PhysRevB.52.15279
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“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)
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“A mercury based cuprate with the “2212&rdquo, structure: Hg2-x(Cu,Pr)xBa2PrCu2O8-\delta”. Martin C, Hervieu M, Van Tendeloo G, Goutenoire F, Michel C, Maignan A, Raveau B, Solid state communications 93, 53 (1995)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.897
Times cited: 6
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“Copper oxycarbonates and mercury-based cuprates: promising high Tc superconductors”. Raveau B, Michel C, Hervieu M, Van Tendeloo G, Martin C, Maignan A, Journal of superconductivity 7, 9 (1994). http://doi.org/10.1007/BF00730359
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 6
DOI: 10.1007/BF00730359
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“Lead-mercury-based superconductors –, the 1212-cuprate Pb0.7Hg0.3Sr2+xCa0.7Nd0.3-xCu2O7-\delta and the new oxycarbonate Pb0.7Hg0.3Sr4Cu2CO3O7”. Martin C, Hervieu M, Huvé, M, Michel C, Maignan A, Van Tendeloo G, Raveau B, Physica: C : superconductivity 222, 19 (1994). http://doi.org/10.1016/0921-4534(94)90109-0
Abstract: A new superconducting mercury oxycarbonate, Pb0.7Hg0.3Sr4Cu2CO3O7, has been synthesized. This tetragonal phase (a = 3.824 angstrom, c= 16.468 angstrom) consists of an intergrowth of two nonsuperconducting compounds, Sr2CuO2CO3 and Pb0.7Hg0.3Sr2CuO5. It exhibits after optimization a critical temperature of 70 K, with a sharp transition and a superconducting volume fraction of 50%. Its behavior can be compared to that of thallium oxycarbonates previously isolated. This study is completed by a reinvestigation of the 1212 cuprate of the system Hg-Pb-Sr-Ca-Nd-Cu. A superconducting phase with the 1212 structure, similar to that previously obtained but with a significantly different composition, Pb0.7Hg0.3Sr2+xCa0.7Nd0.3-xCu2O7, has been obtained, with a T(c onset) of 100 K. The behavior of the latter is compared with other lead-based 1212 cuprates.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 0.942
Times cited: 49
DOI: 10.1016/0921-4534(94)90109-0
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“Copper oxycarbonates and mercury based cuprates: structural mechanisms of new superconductors”. Hervieu M, Michel C, Van Tendeloo G, Martin C, Maignan A, Raveau B, Physica: C : superconductivity 235/240, 25 (1994). http://doi.org/10.1016/0921-4534(94)91305-6
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 0.942
Times cited: 8
DOI: 10.1016/0921-4534(94)91305-6
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“Structural aspects of Bi2-xPbxSr3.5Cu2(CO3)O8-\delta for 0\leq x\leq0.75 : an electron-microscopy study”. Zhang XF, Van Tendeloo G, Amelinckx S, Pelloquin D, Michel C, Hervieu M, Raveau B, Journal of solid state chemistry 113, 327 (1994). http://doi.org/10.1006/jssc.1994.1378
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.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.133
Times cited: 8
DOI: 10.1006/jssc.1994.1378
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“Translation-rotation coupling, phase transitions and elastic phenomena in orientationally disordered crystals”. Lynden-Bell RM, Michel KH, Reviews of modern physics 66, 721 (1994). http://doi.org/10.1103/RevModPhys.66.721
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 29.604
Times cited: 128
DOI: 10.1103/RevModPhys.66.721
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“Crystal field, orientational order, and lattice contraction in solid C60”. Lamoen D, Michel KH, The journal of chemical physics 101, 1435 (1994). http://doi.org/10.1063/1.467768
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.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.952
Times cited: 39
DOI: 10.1063/1.467768
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“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
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“Lead-mercury based superconductors: the 1212 cuprate Pb0.7Hg0.3Sr2+xCa0.7Nd0.3-xCu2O7-\delta and the new oxycarbonate Pb0.7Hg0.3Sr4Cu2CO3O7”. Martin C, Hervieu M, Huvé, M, Michel C, Maignan A, Van Tendeloo G, Raveau B, Physica C-Superconductivity And Its Applications 222, 19 (1994)
Keywords: A1 Journal article; Electron Microscopy for Materials Science (EMAT);
Impact Factor: 0.942
Times cited: 49
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“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)
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“A mercury-based “1201-0201&rdquo, intergrowth HgBa2La2Cu2O8+x: a 53K superconductor”. Huvé, M, Martin C, Van Tendeloo G, Maignan A, Michel C, Hervieu M, Raveau B, Solid state communications 90, 37 (1994)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.897
Times cited: 7
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“Structural characteristics of the 40K superconductor Bi2Sr5Cu3(CO3)2O10: a HREM study”. Hervieu M, Pelloquin D, Michel C, Van Tendeloo G, Raveau B, Journal of solid state chemistry 112, 139 (1994)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.133
Times cited: 5
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“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)
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“Substitution of mercury for thallium in the 2223 cuprate: the 130K superconductor Tl1.6Hg0.4Ba2Cu3O10-x”. Goutenoire F, Maignan A, Van Tendeloo G, Martin C, Michel C, Hervieu M, Raveau B, Solid state communications 90, 47 (1994)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.897
Times cited: 16
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“Crystal field and molecular structure of solid C60”. Lamoen D, Michel KH, Zeitschrift für Physik : B : condensed matter 92, 323 (1993). http://doi.org/10.1007/BF01308749
Abstract: The crystal field in the orientationally disordered phase of C90-fullerite is derived from an intermolecular potential model, which takes into account the geometric difference between double bonds and single bonds. The molecules are modelled as rigid bodies, atoms and single bonds are treated as single interaction centers, while double bonds are described by a distribution of interaction centers along the bond. The crystal field is expanded in terms of cubic rotator functions. The calculated expansion coefficients are compared with empirical values derived from diffraction data. The angular dependence of the crystal field, resulting from an anticlockwise rotation of the molecule around the [111] axis, exhibits an absolute and a secondary minimum at angles of 98-degrees and 38-degrees respectively. The self interaction of the molecule in a deformable lattice is investigated.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Times cited: 25
DOI: 10.1007/BF01308749
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“Neutron and X-ray-scattering cross sections of orientationally disordered solid C60”. Copley JRD, Michel KH, Journal of physics : condensed matter 5, 4353 (1993). http://doi.org/10.1088/0953-8984/5/26/008
Abstract: Differential cross sections for neutron and x-ray scattering have been derived for the orientationally disordered phase of solid C60. Interaction centres are placed at nuclei and at the centres of interatomic bonds. Bragg and diffuse scattering cross sections, for single crystals and for powders, are formulated using symmetry-adapted rotator functions. Thermal averages are calculated taking account of crystal field effects. Thermally averaged orientational distribution functions have also been calculated.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.346
Times cited: 34
DOI: 10.1088/0953-8984/5/26/008
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“Microscopic theory of thermoelastic phenomena and pressure dependence in solid C60”. Lamoen D, Michel KH, Physical review : B : condensed matter and materials physics 48, 807 (1993). http://doi.org/10.1103/PhysRevB.48.807
Abstract: A microscopic theory for the coupling of molecular orientations with acoustic lattice displacements is proposed. The relevant interaction is quadratic in the orientational-order-parameter variables and linear in longitudinal strains. The coupling is evaluated for a complex molecular structure. The intermolecular potential is obtained from interaction centers placed at nuclei and at the centers of interatomic bonds. The free energy is derived and the experimental consequences of the theory are studied. The Clausius-Clapeyron equation for orientational melting is obtained. The theory explains the decrease of the lattice constant at the first-order phase transition and the increase of the transition temperature with applied pressure.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.736
Times cited: 32
DOI: 10.1103/PhysRevB.48.807
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“A new “1201&rdquo, mercury cuprate: the 27K-superconductor HG0.5Bi0.5Sr2-xLaxCuO5-\delta”. Pelloquin D, Michel C, Van Tendeloo G, Maignan A, Hervieu M, Raveau B, Physica: C : superconductivity 214, 87 (1993)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 0.942
Times cited: 62
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