Search

Your search keyword '"Gout, Delphine"' showing total 110 results
Start Over Author "Gout, Delphine"
110 results on '"Gout, Delphine"'

2. Anharmonic Phonons and Magnons in BiFeO3

Author

Delaire, Olivier, Stone, Matthew B., Ma, Jie, Huq, Ashfia, Gout, Delphine, Brown, Craig, Wang, Kefeng, and Ren, Zhifeng

Subjects
Condensed Matter - Materials Science, Condensed Matter - Other Condensed Matter, Condensed Matter - Strongly Correlated Electrons
Abstract

The phonon density of states (DOS) and magnetic excitation spectrum of polycrystalline BiFeO$_3$ were measured for temperatures $200 \leq T \leq 750\,$K, using inelastic neutron scattering (INS). Our results indicate that the magnetic spectrum of BiFeO$_3$ closely resembles that of similar Fe perovskites, such as LaFeO$_3$, despite the cycloid modulation in BiFeO$_3$. We do not find any evidence for a spin gap. A strong $T$-dependence of the phonon DOS was found, with a marked broadening of the whole spectrum, providing evidence of strong anharmonicity. This anharmonicity is corroborated by large-amplitude motions of Bi and O ions observed with neutron diffraction. These results highlight the importance of spin-phonon coupling in this material.

Published
2011
Full Text
View/download PDF

3. Magnetic Phase Transitions in NdCoAsO

Author

McGuire, Michael A., Gout, Delphine J., Garlea, V. Ovidiu, Sefat, Athena S., Sales, Brian C., and Mandrus, David

Subjects
Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons
Abstract

Magnetization measurements reveal that NdCoAsO undergoes three magnetic phase transitions below room temperature. The crystal and magnetic structures of NdCoAsO have been determined by powder neutron diffraction, and the effects of the phase transitions on physical properties are reported. Near 69 K a ferromagnetic state emerges with a small saturation moment of about 0.2 Bohr magnetons, likely on Co atoms. At 14 K the material enters an antiferromagnetic state with propagation vector (0 0 1/2) and small ordered moments (~0.4 Bohr magnetons) on Co and Nd. Near 3.5 K a third transition is observed, and corresponds to the antiferromagnetic ordering, with the same propagation vector, of larger moments on Nd reaching 1.30(2) Bohr magnetons at 1.4 K. In addition, transport properties and heat capacity results are presented, and show anomalies at all three phase transitions., Comment: Some minor changes made, and lower temperature neutron diffraction results are included. Accepted for publication in Physical Review B

Published
2009
Full Text
View/download PDF

12. Atomic distributions in the [gamma]-Brass structure of the Cu-Zn system: A structural and theoretical study

Author

Gourdon, Olivier, Gout, Delphine, Williams, Darrick J., Proffen, Thomas, Hobbs, Sara, and Miller, Gordon J.

Subjects
Copper compounds -- Atomic properties, Zinc compounds -- Atomic properties, Brass -- Atomic properties, Brass -- Structure, Electron configuration -- Analysis, Chemistry
Abstract

The crystal structures, atomic distributions, and theoretical electronic structures of a series of [Cu.sub.5-x][Zn.sub.8+x] compounds (x = -0.59, -0.31, 0.00, 0.44, and 0.79) with the [gamma]-brass structure are reported with the goal of identifying chemical influences on the observed phase width. In all cases, the 26-atom cluster building up the [gamma]-brass structure shows a constant inner [[Cu.sub.4][Zn.sub.4]] tetrahedral star with compositional variation occurring at the outer octahedron and cuboctahedron.

Published
2007

23. Rhombohedrally distorted [gamma]-brasses [Cr.sub.1-x][Fe.sub.x]Ga

Author

Hyunjin Ko, Gourdon, Olivier, Gout, Delphine, Eun-Deok Mun, Thimmaiah, Srinivasa, and Miller, Gordon J.

Subjects
Binding energy -- Analysis, Chromium alloys -- Chemical properties, Chromium alloys -- Structure, Chromium alloys -- Magnetic properties, Crystallography -- Usage, Gallium compounds -- Structure, Gallium compounds -- Chemical properties, Gallium compounds -- Magnetic properties, Neutrons -- Diffraction, Neutrons -- Usage, Chemistry
Published
2010

25. Composition-Structure relationships in Polar intermetallics: experimental and theoretical studies of LaNi(sub 1+x)Al(sub 6-x) (x=0.44)

Author

Gout, Delphine, Benbow, Evan, Miller, Gordon J., and Gourdon, Olivier

Subjects
Aluminum compounds -- Structure, Aluminum compounds -- Chemical properties, Nickel compounds -- Structure, Nickel compounds -- Chemical properties, Lanthanum -- Structure, Lanthanum -- Chemical properties, X-rays -- Diffraction, X-rays -- Research, Chemistry
Abstract

The discovery of a new compound in the lanthanum-nickel-aluminum system, LaNi(sub 1+x)Al(sub 6-x) (x=0.44) and determination of its structure by single-crystal X-ray diffraction is reported. The compound exhibits a large open cavity in the center of the unit cell, which could be filled by a guest atom such as hydrogen or small alkali metals like lithium.

Published
2004

32. Magnetic phase transitions in NdCoAsO

Author

McGuire, Michael A., primary, Gout, Delphine J., additional, Garlea, V. Ovidiu, additional, Sefat, Athena S., additional, Sales, Brian C., additional, and Mandrus, David, additional

Published
2010
Full Text
View/download PDF

47. Atomic Distributions in the γ-Brass Structure of the Cu-Zn System: A Structural and Theoretical Study.

Author

Gourdon, Olivier, Gout, Delphine, Wiiiiams, Darrick J., Proffen, Thomas, Hobbs, Sara, and Miller, Gordon J.

Subjects
*ATOMIC structure, *BRASS, *COPPER, *ZINC, *ATOMS, *ELECTRONIC structure
Abstract

The crystal structures, atomic distributions, and theoretical electronic structures of five different Cu5-xZn8+x γ-brass compounds (x = -0.59(3), -0.31(3), 0.00(3), 0.44(3), and 0.79(3)) are reported with the goal of identifying chemical influences on the observed phase width. These structures have been refined by both neutron and X-ray powder diffraction to obtain accurate crystal chemical parameters. All compounds crystallize in the space group I43m (No. 217) (Z= 4), and the unit cell parameters are a = 8.8565(4), 8.8612(5), 8.8664(3) , 8.8745(4), and 8.8829(7) Å, respectively, for Cu5.59Zn7.41, Cu5.31Zn7.69, Cu5.00Zn8.00, Cu4.56Zn8.44, and Cu4.21Zn8.79. The results indicate specific site substitutions on both sides of the ideal composition "Cu5Zn8". In all cases, the 26-atom cluster building up the γ-brass structure shows a constant inner [Cu4Zn4] tetrahedral star with compositional variation occurring at the outer octahedron and cuboctahedron. First principles and semiempirical electronic structure calculations using both a COHP and Mulliken population analysis were performed to understand the observed compositional range and to address the "coloring problem" for the site preferences of Cu and Zn atoms for this series of compounds. [ABSTRACT FROM AUTHOR]

Published
2007
Full Text
View/download PDF

48. Composition—Structure Relationships in Polar Intermetallics: Experimental and Theoretical Studies of LaNi1+xAl6-x (x = 0.44).

Author

Gout, Delphine, Benbow, Evan, Gourdon, Olivier, and Miller, Gordon J.

Subjects
*INTERMETALLIC compounds, *LANTHANUM compounds, *INORGANIC synthesis, *X-ray diffraction, *GALLIUM compounds, *MOLECULAR structure
Abstract

A new ternary aluminide, LaNi1+xAl6-x (x = 0.44), has been synthesized from La, Ni, and Al in sealed silica tubes. Its structure, determined by single-crystal X-ray diffraction, is tetragonal P4/mmm (No. 123) with Z = 1 and has the lattice parameters a = 4.200(8) and c = 8.080(8) Å. Refinement based on Fo² yielded R1 = 0.0197 and wR2 = 0.020 [/> 2σ(/)]. The compound adopts a structure type previously observed in SrAu2Ga5 and EuAu2Ga5. The atomic arrangement is closely related to the one in BaAl4 as well as in other rare-earth gallide compounds such as LaNi0.6Ga6, HoCoGa5, Ce4Ni2Ga20, Ce4Ni2Ga17, Ce4NiGa18, and Ce3Ni2Ga15.. This structure exhibits a large open cavity which may be filled by a guest atom. Band structure calculations using density functional theory have been carried out to understand the stability of this new compound. [ABSTRACT FROM AUTHOR]

Published
2004
Full Text
View/download PDF

49. Crystallographic, electronic and magnetic studies of Ce4Ni6Al23: a new ternary intermetallic compound in the cerium–nickel–aluminum phase diagram

Author

Gout, Delphine, Benbow, Evan, Gourdon, Olivier, and Miller, Gordon J.

Subjects
*ALUMINUM, *ELECTRONIC structure, *PHASE transitions
Abstract

The Al-rich portion of the ternary Ce–Ni–Al has been investigated and a new ternary phase of composition Ce4Ni6Al23 has been found. This compound crystallizes in the monoclinic space group C2/m with the cell parameters a=16.042(8), b=4.140(4), c=18.380(8) A˚ and β=113.24(5)°. The structure has been determined by single crystal X-ray diffraction. The local environment of Ni and Ce is close to what is observed in the CeNi2Al5 and CeNiAl4 structures. Band structure calculations, using the tight-binding–linear muffin-tin orbital–atomic-spheres approximation (TB-LMTO-ASA) method, have been performed to understand the electronic structure of Ce4Ni6Al23 and the results are discussed in connection with those two other Ce–Ni–Al intermetallic compounds, which possess heavy-fermion behavior. Magnetic and heat capacity measurements have also been measured to analyze the low-temperature magnetic behavior of this new compound. [Copyright &y& Elsevier]

Published
2003
Full Text
View/download PDF

50. Structural Investigation and Luminescence Properties of the Ce3(SiS4)2X(X=Cl, Br, I) Family and the La3−xCex(SiS4)2I (0≤x≤1) Solid Solution

Author

Riccardi, Regis, Gout, Delphine, Gauthier, Gilles, Guillen, François, Jobic, Stéphane, Garcia, Alain, Huguenin, Denis, Macaudière, Pierre, Fouassier, Claude, and Brec, Raymond

Abstract

Recently prepared Ce3(SiS4)2I exhibits a strong room temperature luminescence in the blue region of the visible spectrum associated to a CeIII-5d1→CeIII-4f1electronic transition. In order to approach the emission mechanisms, the La3−xCex(SiS4)2I family has been investigated by optical techniques at 6 and 300 K. At low temperature luminescence of the two crystallographically distinct cerium cations was evidenced along with an intrinsic luminescence of the lanthanum matrix. The influence of the halogenide on the optical properties has been studied through the substitution of iodine by chlorine and bromine which permits us to follow the increase in energy of the 4f–5dgap in the Cl

Published
1999
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results