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Neutron Scattering Experiments (neutron + scattering_experiment)

Distribution by Scientific Domains
Polymers and Materials Science42%
Chemistry42%

Selected Abstracts

Metallic Glasses: Nanoscale Solute Partitioning in Bulk Metallic Glasses (Adv. Mater.

ADVANCED MATERIALS, Issue 3 2009
3/2009)
Devitrification of bulk metallic glass leads to novel microstructures with high-density nanoscale crystalline precipitates evenly distributed in a glassy matrix. Xun-Li Wang and co-workers report on p. 305 that significant chemical segregation is revealed in unprecedented detail by atom-probe tomography. This level of detail is crucial for understanding the interference peaks observed in small-angle X-ray and neutron scattering experiments. [source]

Nanoscale Solute Partitioning in Bulk Metallic Glasses,

ADVANCED MATERIALS, Issue 3 2009
Ling Yang
Devitrification of bulk metallic glass leads to a novel microstructure, with high-density nanoscale crystalline precipitates evenly distributed in a glassy matrix. Significant chemical segregation is revealed at unprecedented detail by atom-probe tomography. This level of detail is crucial for understanding the interference peaks observed in small-angle X-ray and neutron scattering experiments, an unsolved mistery for over a decade. [source]

Cold neutron beam focusing by a superconducting sextupole magnet

JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2003
Jun-ichi Suzuki
We have developed a superconducting sextupole magnet with about 50 mm in bore diameter to focus cold neutron beams with large cross-section and have investigated its focusing and polarizing effect. Large gain in neutron intensity and high neutron polarization have been obtained by numerical simulation for highly collimated neutron beams. We discuss applications of this magnet for small-angle neutron scattering experiments. [source]

Temperature and pressure effects on structural formations in a ternary microemulsion

JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2000
M. Nagao
Small angle neutron scattering experiments were conducted on a temperature-induced phase transition in a ternary microemulsion composed of AOT (dioctyl sulfosuccinate sodium salt), D2 O and n -decane and the results were compared with those of pressure-induced one. Although the static features of both the temperature- and the pressure-induced phase behaviour were similar, a temperature dependence of its characteristic repeat distance at high temperature was quite different from a pressure dependence of that at high pressure. Neutron spin echo experiments were also performed on both the phase transitions. The dynamics of the high temperature phase was different from that of the high pressure phase. These results indicated that the effect of pressure on the structural formation was different from that of temperature. [source]

Synthesis and properties of crosslinked polyvinylformamide and polyvinylamine hydrogels in conjunction with silica particles

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 18 2002
Torsten Meyer
Abstract Polyvinylamine hydrogels with silica particles encapsulated (PVAm/silica) were produced by a two-step synthesis. In the first step, polyvinylformamide/silica (PVFA/silica) hybrids were synthesized from vinylformamide (VFA) and 1,3-divinylimidazolidin-2-one (1,3-bisvinylethyleneurea, BVU), as the crosslinker, by radical copolymerization in silica/water suspensions using different compositions of VFA/BVU. The target product PVAm/silica was obtained by acidic hydrolysis of the PVFA/silica hydrogels in a second step. The chemical structures of both hydrogels, PVFA/silica and PVAm/silica, respectively, were revealed by solid-state 13C(1H) cross-polarity/magic-angle spinning NMR spectroscopy. Both hydrogels swelled significantly in water. The swelling capacity of the two systems was characterized by the correlation length , (or hydrodynamic blob size) of the network meshes with small-angle neutron scattering experiments. , is significantly larger for PVAm/silica than for PVFA/silica, which corresponds to the observed higher swelling capacity of this polyelectrolyte material. Furthermore, the swelling behavior of the hybrid hydrogels was quantitatively described in terms of free swell capacity, centrifuge-retention capacity, adsorption against pressure, and free swell rate as compared with values of the corresponding copolymer hydrogels. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3144,3152, 2002 [source]

Quantum criticality of Ce1,xLaxRu2Si2: The magnetically ordered phase

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 3 2010
Stéphane Raymond
Abstract We report specific heat and neutron scattering experiments performed on the system Ce1,xLaxRu2Si2 on the magnetic side of its quantum critical phase diagram. The Kondo temperature does not vanish at the quantum phase transition and elastic scattering indicates a gradual localization of the magnetism when x increases in the ordered phase. [source]

A Family of Ferro- and Antiferromagnetically Coupled Decametallic Chromium(III) Wheels

CHEMISTRY - A EUROPEAN JOURNAL, Issue 5 2006
David M. Low Dr.
Abstract The synthesis and crystal structures of a family of decametallic CrIII "molecular wheels" are reported, namely [Cr10(OR)20(O2CR,)10] [R,=Me, R=Me (1), Et (2); R,=Et, R=Me (3), Et (4); R,=CMe3, R=Me (5), Et (6)]. Magnetic studies on 1,6 reveal a remarkable dependence of the magnetic behaviour on the nature of R. In each pair of complexes with a common carboxylate (R,) the nearest neighbour Cr,,,Cr magnetic exchange coupling is more antiferromagnetic for the ethoxide-bridged (R=Et) cluster than for the methoxide analogue. In complexes 2, 4 and 6 the overall coupling is weakly antiferromagnetic resulting in diamagnetic (S=0) ground states for the cluster, whilst in 1 and 5 it is weakly ferromagnetic thus resulting in very high-spin ground states. This ground state has been probed directly in the perdeuterated version of 1 ([D]1) by inelastic neutron scattering experiments, and these support the S=15 ground state expected for ferromagnetic coupling of ten CrIII ions, and they also indicate that a single J -value model is inadequate. The ground state of 5 is large but not well defined. The trends in J on changing R are further supported by density functional calculations on 1,6, which are in excellent agreement with experiment. The very large changes in the nature of the ground state between 1 and 2, and 5 and 6 are the result of relatively small changes in J that happen to cross J=0, hence changing the sign of J. [source]