Evidence from x-ray diffraction of orientational ordering in phase III of solid hydrogen at pressures up to 183 GPa

2010 ◽  
Vol 82 (6) ◽  
Author(s):  
Yuichi Akahama ◽  
Manabu Nishimura ◽  
Haruki Kawamura ◽  
Naohisa Hirao ◽  
Yasuo Ohishi ◽  
...  
Keyword(s):  
Solid Hydrogen ◽  
Phase Iii ◽  
X Ray Diffraction ◽  
X Ray ◽  
Orientational Ordering

scholarly journals Raman scattering and x-ray diffraction experiments for phase III of solid hydrogen

2010 ◽  
Vol 215 ◽  
pp. 012056 ◽  
Author(s):  
Y Akahama ◽  
H Kawamura ◽  
N Hirao ◽  
Y Ohishi ◽  
K Takemura
Keyword(s):  
Raman Scattering ◽  
Solid Hydrogen ◽  
Phase Iii ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Raman scattering and X-ray diffraction studies on phase III of solid hydrogen

2017 ◽  
Vol 950 ◽  
pp. 042060 ◽  
Author(s):  
Y Akahama ◽  
Y Mizuki ◽  
S Nakano ◽  
N Hirao ◽  
Y Ohishi
Keyword(s):  
Raman Scattering ◽  
Solid Hydrogen ◽  
Phase Iii ◽  
X Ray Diffraction ◽  
X Ray

Structures and phase transitions in a new ferroelectric – pyridinium chlorochromate – studied by X-ray diffraction, DSC and dielectric methods

2012 ◽  
Vol 68 (2) ◽  
pp. 128-136 ◽  
Author(s):  
Hanna Małuszyńska ◽  
Piotr Czarnecki ◽  
Anna Czarnecka ◽  
Zdzisław Pająk
Keyword(s):  
Phase Transitions ◽  
Pyridinium Salt ◽  
Diffraction Method ◽  
Phase Iii ◽  
Pyridinium Chlorochromate ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Intermediate Phases ◽  
Ferroelectric Hysteresis

Pyridinium chlorochromate, [C5H5NH]+[ClCrO3]− (hereafter referred to as PyClCrO3), was studied by X-ray diffraction, differential scanning calorimetry (DSC) and dielectric methods. Studies reveal three reversible phase transitions at 346, 316 and 170 K with the following phase sequence: R\bar 3m (I) → R3m (II) → Cm (III) → Cc (IV), c′ = 2c. PyClCrO3 is the first pyridinium salt in which all four phases have been successfully characterized by a single-crystal X-ray diffraction method. Structural results together with dielectric and calorimetric studies allow the classification of the two intermediate phases (II) and (III) as ferroelectric with the Curie point at 346 K, and the lowest phase (IV) as most probably ferroelectric. The ferroelectric hysteresis loop was observed only in phase (III). The high ionic conductivity hindered its observation in phase (II).

Crystal Structure of Trimethylammonium Perchlorate in Three Solid Phases Including the Ionic Plastic Phase Obtainable above 480 K

1994 ◽  
Vol 49 (6) ◽  
pp. 723-726 ◽  
Author(s):  
Hiroyuki Ishida ◽  
Yoshihiro Kubozono ◽  
Setsuo Kashino ◽  
Ryuichi Ikeda
Keyword(s):  
Phase Iii ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Cscl Type ◽  
Thermal Measurements ◽  
Plastic Phase ◽  
Solid Phases ◽  
Phase Phase

Abstract The crystal structures of (CH3)3NHClO4 in three solid phases were studied by X-ray diffraction techniques. X-ray powder patterns taken at ca. 500 and 445 K revealed that the plastic phase (Phase I) attainable above 480 K crystallizes in a CsCl-type cubic structure with a = 5.845 (1) Å, Z = 1, V = 199.7 (2) Å3, and Dx = 1.327 g cm -3, while Phase II, stable between 480 and 396 K, forms a tetragonal structure with a = 9.912 (4), c = 7.01 (2) Å, Z = 4, V = 689 (3) Å3, and Dx = 1.54 gem -3. The room temperature phase (Phase III) was studied by single crystal X-ray diffraction and found to form a monoclinic lattice with space group P21 , a = 5.749(1), b = 8.670(1), c = 7.5585 (9) Å, ß = 102.66 (1)°, Z = 2, V = 367.6 (2) Å3 , and Dx= 1.441 g cm -3. Thermal measurements, differential thermal analysis and differential scanning calorimetry, were carried out on these solid phases, and the obtained results were compared with those observed for (CH3)3NHBF4.

scholarly journals Orientational disorder and phase transitions in crystals of (NH4)2NbOF5

2008 ◽  
Vol 64 (5) ◽  
pp. 527-533 ◽  
Author(s):  
Anatoly A. Udovenko ◽  
Natalia M. Laptash
Keyword(s):  
Phase Transitions ◽  
Phase Ii ◽  
Central Atom ◽  
Crystal Form ◽  
Partial Ordering ◽  
Phase Iii ◽  
X Ray Diffraction ◽  
Dynamic Nature ◽  
Two Phase ◽  
X Ray

Ammonium oxopentafluoroniobate, (NH4)2NbOF5, was synthesized in a single-crystal form and the structures of its different phases were determined by X-ray diffraction at three temperatures: phase (I) at 297 K, phase (II) at 233 K and phase (III) at 198 K. The distorted [NbOF5]2− octahedra are of similar geometry in all three structures, with the central atom shifted towards the O atom. The structure of (I) is disordered, with three spatial orientations of the [NbOF5]2− octahedron related by a jump rotation around the pseudo-threefold local axis such that the disorder observed is of a dynamic nature. As the temperature decreases, the compound undergoes two phase transitions. The first is accompanied by full anionic ordering and partial ordering of the ammonium groups (phase II). The structure of (III) is completely ordered. The F and O atoms in the structures investigated were identified via the Nb—X (X = O and F) distances. The crystals of all three phases are twinned.

scholarly journals High-Pressure Behaviors of Ag2S Nanosheets: An in Situ High-Pressure X-Ray Diffraction Research

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1640
Author(s):  
Ran Liu ◽  
Bo Liu ◽  
Quan-Jun Li ◽  
Bing-Bing Liu
Keyword(s):  
High Pressure ◽  
Phase I ◽  
Phase Ii ◽  
Structural Phase ◽  
Phase Iii ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Phase ◽  
Ag2s Nanoparticles

An in situ high-pressure X-ray diffraction study was performed on Ag2S nanosheets, with an average lateral size of 29 nm and a relatively thin thickness. Based on the experimental data, we demonstrated that under high pressure, the samples experienced two different high-pressure structural phase transitions up to 29.4 GPa: from monoclinic P21/n structure (phase I, α-Ag2S) to orthorhombic P212121 structure (phase II) at 8.9 GPa and then to monoclinic P21/n structure (phase III) at 12.4 GPa. The critical phase transition pressures for phase II and phase III are approximately 2–3 GPa higher than that of 30 nm Ag2S nanoparticles and bulk materials. Additionally, phase III was stable up to the highest pressure of 29.4 GPa. Bulk moduli of Ag2S nanosheets were obtained as 73(6) GPa for phase I and 141(4) GPa for phase III, which indicate that the samples are more difficult to compress than their bulk counterparts and some other reported Ag2S nanoparticles. Further analysis suggested that the nanosize effect arising from the smaller thickness of Ag2S nanosheets restricts the relative position slip of the interlayer atoms during the compression, which leads to the enhancing of phase stabilities and the elevating of bulk moduli.

X-ray studies of the phase transitions of bis(guanidinium)zirconium bis(nitrilotriacetate) hydrate, (C(NH2)3)2Zr(N(CH2COO)3)2 · H2O

1999 ◽  
Vol 214 (3) ◽  
Author(s):  
J. Schreuer ◽  
E. Haussühl
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Phase I ◽  
Phase Iii ◽  
Group Symmetry ◽  
Translational Symmetry ◽  
X Ray Diffraction ◽  
Space Group Symmetry ◽  
X Ray ◽  
Structural Differences

AbstractThe structural differences of phase I (at 193 K) and phase III (293 K) of bis(guanidinium)zirconium bis(nitrilotriacetate) hydrate were investigated by means of X-ray diffraction. The phase transition III → I is characterised by a loss of translational symmetry as it is indicated by the change of space group symmetry from

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