scholarly journals Ab initiolattice dynamics simulations and inelastic neutron scattering spectra for studying phonons inBaFe2As2: Effect of structural phase transition, structural relaxation, and magnetic ordering

2009 ◽  
Vol 79 (6) ◽  
Author(s):  
Mohamed Zbiri ◽  
Helmut Schober ◽  
Mark R. Johnson ◽  
Stephane Rols ◽  
Ranjan Mittal ◽  
...  
Keyword(s):  
Phase Transition ◽  
Neutron Scattering ◽  
Structural Phase Transition ◽  
Structural Relaxation ◽  
Inelastic Neutron Scattering ◽  
Structural Phase ◽  
Magnetic Ordering ◽  
Inelastic Neutron ◽  
Scattering Spectra ◽  
Dynamics Simulations

Neutron-scattering studies of the phase transitions in high-pressure ices during annealing

2003 ◽  
Vol 81 (1-2) ◽  
pp. 401-407 ◽  
Author(s):  
Y. Wang ◽  
A I Kolesnikov ◽  
S L Dong ◽  
J C Li
Keyword(s):  
Phase Transition ◽  
Neutron Scattering ◽  
Inelastic Neutron Scattering ◽  
Covalent Bond ◽  
Transition Process ◽  
Inelastic Neutron ◽  
Incoherent Neutron Scattering ◽  
Phase Transition Process ◽  
Scattering Spectra ◽  
Three Body

Inelastic incoherent neutron scattering was used to study the phase transition process of high-density amorphous (HDA) ice to low-density amorphous (LDA) ice by thermal treatment. The results show that when the annealing temperature is lower than 136 K no obvious phase-transition is observed, and transformation of the HDA ice to the LDA ice occurs between 136 and 144 K. From comparison of the measured inelastic neutron-scattering spectra for HDA ice and ice Ih, it is found that the internal interactions (covalent bond O—H and three-body interaction H–O–H) are stronger in HDA ice, which correlates with the longer nearest O–O distances in HDA ice compared to ice Ih (2.80 and 2.75 Å, respectively). The report also discusses the differences in vibrational spectra of LDA ices obtained by different methods (annealing HDA ice and depositing water vapour on a cold substrate). PACS No.: 64.60-i

Neutron-Scattering Study of the Structural Phase Transition in the One-Dimensional ConductorK2Pt(CN)4Br0.3·3D2O

1974 ◽  
Vol 32 (15) ◽  
pp. 836-839 ◽  
Author(s):  
B. Renker ◽  
L. Pintschovius ◽  
W. Gläser ◽  
H. Rietschel ◽  
R. Comès ◽  
...  
Keyword(s):  
Phase Transition ◽  
Neutron Scattering ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
One Dimensional ◽  
Scattering Study ◽  
Neutron Scattering Study ◽  
The One

Infrared, Raman, and Inelastic Neutron Scattering Spectra of Dodecahedrane:  anIhMolecule inThSite Symmetry

2005 ◽  
Vol 109 (15) ◽  
pp. 3418-3424 ◽  
Author(s):  
Bruce S. Hudson ◽  
Damian G. Allis ◽  
Stewart F. Parker ◽  
Anibal J. Ramirez-Cuesta ◽  
Henryk Herman ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Scattering Spectra

Phase Transitions and Water Dynamics of [Mn(H2O)6](ClO4 )2 Studied by Differential Scanning Calorimetry and Neutron Scattering Methods

2000 ◽  
Vol 55 (9-10) ◽  
pp. 759-764 ◽  
Author(s):  
E. Mikuli ◽  
A. Migdał-Mikuli ◽  
I. Natkaniec ◽  
J. Mayer
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Neutron Scattering ◽  
Structural Phase Transition ◽  
Room Temperature ◽  
Structural Phase ◽  
Water Dynamics ◽  
Water Molecules ◽  
Temperature Phase ◽  
Solid Phases

Abstract DSC measurements performed at 95 -290 K have shown that [Mn(H 2 O) 6 ](CIO 4) 2 possesses, besides a high-temperature phase, existing above 323 K, four low-temperature solid phases. The inelastic incoherent neutron scattering (IINS) spectra and neutron powder diffraction (NPD) pat-terns registered at 20 -290 K have supported the DSC results and provided evidence that the investigated substance possesses even more than five solid phases. The IINS spectra have shown that in the room-temperature phase, water molecules perform fast stochastic reorientation at the picosecond scale. The orientational disorder characteristic for the room-temperature phase can be easily overcooled and frozen. Even by relatively slow cooling at ca. 40 K/hour a metastable, orientational (protonic) glass phase is formed below ca. 160 K. Below ca. 100 K, a structural phase transition was observed by the NPD, however the IINS spectra indicate existence of the pure ordered low-temperature phase only after annealing the sample for a few hours at 100 K. On heating, a structural phase transition takes place at ca. 120 K, and at ca. 225 K water molecules begin fast reorientation.

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