scholarly journals Neutron and high-pressure X-ray diffraction study of hydrogen-bonded ferroelectric rubidium hydrogen sulfate

2016 ◽  
Vol 72 (6) ◽  
pp. 855-863 ◽  
Author(s):  
Jack Binns ◽  
Garry J McIntyre ◽  
Simon Parsons
Keyword(s):  
High Pressure ◽  
Applied Pressure ◽  
Ferroelectric Material ◽  
Ferroelectric Materials ◽  
Hydrogen Sulfate ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Pressure Phase ◽  
Hydrogen Bonded

The pressure- and temperature-dependent phase transitions in the ferroelectric material rubidium hydrogen sulfate (RbHSO4) are investigated by a combination of neutron Laue diffraction and high-pressure X-ray diffraction. The observation of disordered O-atom positions in the hydrogen sulfate anions is in agreement with previous spectroscopic measurements in the literature. Contrary to the mechanism observed in other hydrogen-bonded ferroelectric materials, H-atom positions are well defined and ordered in the paraelectric phase. Under applied pressure RbHSO4undergoes a ferroelectric transition before transforming to a third, high-pressure phase. The symmetry of this phase is revised to the centrosymmetric space groupP21/c, resulting in the suppression of ferroelectricity at high pressure.

Phase transitions in ReO3studied by high-pressure X-ray diffraction

2000 ◽  
Vol 33 (2) ◽  
pp. 279-284 ◽  
Author(s):  
J.-E. Jørgensen ◽  
J. Staun Olsen ◽  
L. Gerward
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Powder Diffraction ◽  
Ambient Pressure ◽  
Rhombohedral Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxygen Ions ◽  
Pressure Phase ◽  
Related Phase

ReO3has been studied at pressures up to 52 GPa by X-ray powder diffraction. The previously observed cubicIm3¯ high-pressure phase was shown to transform to a monoclinic MnF3-related phase at about 3 GPa. All patterns recorded above 12 GPa could be indexed on rhombohedral cells. The compressibility was observed to decrease abruptly at 38 GPa. It is therefore proposed that the oxygen ions are hexagonally close packed above this pressure, giving rise to two rhombohedral phases labelled I and II. The zero-pressure bulk moduliBoof the observed phases were determined and the rhombohedral phase II was found to have an extremely large value of 617 (10) GPa. It was found that ReO3transforms back to thePm3¯mphase found at ambient pressure.

High-Pressure Phase Transitions of Cubic Y 2 O 3 under High Pressures by In-situ Synchrotron X-Ray Diffraction

2019 ◽  
Vol 36 (4) ◽  
pp. 046103 ◽  
Author(s):  
Sheng Jiang ◽  
Jing Liu ◽  
Xiao-Dong Li ◽  
Yan-Chun Li ◽  
Shang-Ming He ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
High Pressures ◽  
High Pressure Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pressure Phase

High-pressure and high-temperature sintering of nanostructured bulk NiAl materials

2009 ◽  
Vol 24 (6) ◽  
pp. 2089-2096 ◽  
Author(s):  
Shanmin Wang ◽  
Duanwei He ◽  
Yongtao Zou ◽  
Jianjun Wei ◽  
Li Lei ◽  
...  
Keyword(s):  
High Pressure ◽  
Indentation Hardness ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
High Pressure And Temperature ◽  
X Ray ◽  
High Pressure Sintering ◽  
Tentative Interpretation ◽  
Surface Shell ◽  
First Time

Nanostructured bulk NiAl materials were prepared at high pressure and temperature (0–5.0 GPa and 600–1500 °C, respectively). The sintered samples were characterized by x-ray diffraction, scanning electron microscope, density, and indentation hardness measurements. The results show that NiAl nanoparticles may have a compressed surface shell, which may be the reason why NiAl nanomaterials were difficult to densify sintering using conventional methods and why high-pressure sintering was an effective approach. We also observed that B2-structured NiAl could undergo a temperature-dependent phase transition and could be transformed into Al0.9Ni4.22 below 1000 °C for the first time. It is interesting to note that Vickers hardness decreased as grain size decreased below ∼30 nm, indicating that the inverse Hall-Petch effect may be observed in nano-polycrystalline NiAl (n-NiAl) samples. Moreover, a tentative interpretation was developed for high-pressure nanosintering, based on the shell-core model of nanoparticles.

X-ray diffraction measurements of Mo melting to 119 GPa and the high pressure phase diagram

2009 ◽  
Vol 130 (12) ◽  
pp. 124509 ◽  
Author(s):  
D. Santamaría-Pérez ◽  
M. Ross ◽  
D. Errandonea ◽  
G. D. Mukherjee ◽  
M. Mezouar ◽  
...  
Keyword(s):  
Phase Diagram ◽  
High Pressure ◽  
High Pressure Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pressure Phase

A new high-pressure phase transition in clinoferrosilite: In situ single-crystal X-ray diffraction study

2017 ◽  
Vol 102 (3) ◽  
pp. 666-673 ◽  
Author(s):  
Anna Pakhomova ◽  
Leyla Ismailova ◽  
Elena Bykova ◽  
Maxim Bykov ◽  
Tiziana Boffa Ballaran ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Single Crystal ◽  
Diffraction Study ◽  
High Pressure Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Pressure Phase Transition ◽  
Pressure Phase

Crystalline structure of the TiO2 II high-pressure phase at 293, 223, and 133 K according to single-crystal x-ray diffraction data

2007 ◽  
Vol 52 (4) ◽  
pp. 195-199 ◽  
Author(s):  
S. K. Filatov ◽  
N. A. Bendeliani ◽  
B. Albert ◽  
J. Kopf ◽  
T. I. Dyuzheva ◽  
...  
Keyword(s):  
High Pressure ◽  
Single Crystal ◽  
Crystalline Structure ◽  
Diffraction Data ◽  
High Pressure Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pressure Phase

X-Ray Analysis of High Pressure Torsion Induced Nanostructures in Ti and Ni

2006 ◽  
Vol 114 ◽  
pp. 329-336 ◽  
Author(s):  
A.R. Kilmametov ◽  
Ruslan Valiev ◽  
Igor V. Alexandrov
Keyword(s):  
High Pressure ◽  
High Pressure Torsion ◽  
Applied Pressure ◽  
Orientation Distribution ◽  
Nanocrystalline State ◽  
Cubic Symmetry ◽  
X Ray ◽  
Ω Phase ◽  
Commercially Pure ◽  
Pressure Phase

X-ray investigations revealed that the increase in the applied pressure during high pressure torsion (HPT) of commercially pure Ti leads not only to substructure refinement with an increase of the dislocation density and microstrain level but also to an α→ ω phase transition at room temperature. The coexistence of both α and ω phases, the latter known as a high pressure phase, in the ratio approximately of 1:3 has been obtained after removal of thehigh pressure. Texture analysis of electodeposited Ni after HPT discovered a new form of crystallite orientation distribution in the nanocrystalline state. A nearly random orientation crystallite distribution has been observed unlike the “traditional” case of a shear texture forming in cubic symmetry metals. The crystallographic texture data obtained were considered as experimental evidence of the changed plastic deformation mechanisms in nanocrystalline Ni produced by HPT.

Sign in / Sign up

Export Citation Format

Share Document