X-ray diffraction investigations of CaF2 at high pressure

1992 ◽  
Vol 25 (5) ◽  
pp. 578-581 ◽  
Author(s):  
L. Gerward ◽  
J. S. Olsen ◽  
S. Steenstrup ◽  
M. Malinowski ◽  
S. Åsbrink ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Synchrotron Radiation ◽  
High Pressures ◽  
Low Pressure ◽  
Single Crystal Sample ◽  
X Ray Diffraction ◽  
Crystal Sample ◽  
X Ray ◽  
Pressure Phase

Synchrotron-radiation X-ray diffraction studies of CaF2 at high pressures have been performed on a powder sample up to 45 GPa and on a single-crystal sample up to 9.4 GPa. The bulk modulus of the low-pressure phase was determined to be B 0 = 87 (5) GPa. A phase transition was observed at about 9.5 GPa. The transition is accompanied by a volume contraction of 11%. The high-pressure phase is orthorhombic PbCl2 type (space group Pbnm). The sample only partially reverts to the low-pressure phase upon release of pressure.

Pressure-Induced Fm-3m R-3 Phase Transition in NaSbF6

1997 ◽  
Vol 53 (1) ◽  
pp. 25-31 ◽  
Author(s):  
H. Sowa
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
High Pressure ◽  
Sphere Packing ◽  
Low Pressure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pressure Phase ◽  
Type Crystal

High-pressure X-ray diffraction measurements on NaSbF6 powder were performed up to 5.63 (7) GPa. At ∼0.1 GPa the cubic low-pressure phase with ordered ReO3-type crystal structure undergoes a phase transition into a rhombohedral LiSbF6-type modification. The high-pressure behaviour of this phase is characterized by rotations and distortions of the coordination octahedra, but it also can be described with a sphere-packing deformation. The octahedral distortions are probably caused by cation–cation repulsions.

scholarly journals Crystal and electronic structure engineering of tin monoxide by external pressure

2021 ◽  
Author(s):  
Kun Li ◽  
Junjie Wang ◽  
Vladislav A. Blatov ◽  
Yutong Gong ◽  
Naoto Umezawa ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Band Gap ◽  
High Pressures ◽  
Low Pressure ◽  
Widespread Application ◽  
Space Group ◽  
Tin Monoxide ◽  
High Possibility ◽  
Pressure Phase

AbstractAlthough tin monoxide (SnO) is an interesting compound due to its p-type conductivity, a widespread application of SnO has been limited by its narrow band gap of 0.7 eV. In this work, we theoretically investigate the structural and electronic properties of several SnO phases under high pressures through employing van der Waals (vdW) functionals. Our calculations reveal that a metastable SnO (β-SnO), which possesses space group P21/c and a wide band gap of 1.9 eV, is more stable than α-SnO at pressures higher than 80 GPa. Moreover, a stable (space group P2/c) and a metastable (space group Pnma) phases of SnO appear at pressures higher than 120 GPa. Energy and topological analyses show that P2/c-SnO has a high possibility to directly transform to β-SnO at around 120 GPa. Our work also reveals that β-SnO is a necessary intermediate state between high-pressure phase Pnma-SnO and low-pressure phase α-SnO for the phase transition path Pnma-SnO →β-SnO → α-SnO. Two phase transition analyses indicate that there is a high possibility to synthesize β-SnO under high-pressure conditions and have it remain stable under normal pressure. Finally, our study reveals that the conductive property of β-SnO can be engineered in a low-pressure range (0–9 GPa) through a semiconductor-to-metal transition, while maintaining transparency in the visible light range.

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

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

scholarly journals Study on the High-Pressure Behavior of Goethite up to 32 GPa Using X-Ray Diffraction, Raman, and Electrical Impedance Spectroscopy

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 99 ◽  
Author(s):  
Ruilian Tang ◽  
Jiuhua Chen ◽  
Qiaoshi Zeng ◽  
Yan Li ◽  
Xue Liang ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Impedance Spectroscopy ◽  
Electrical Impedance ◽  
High Pressures ◽  
Structural Phase ◽  
Second Order ◽  
Electrical Impedance Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray

Goethite is a major iron-bearing sedimentary mineral on Earth. In this study, we conducted in situ high-pressure x-ray diffraction, Raman, and electrical impedance spectroscopy measurements of goethite using a diamond anvil cell (DAC) at room temperature and high pressures up to 32 GPa. We observed feature changes in both the Raman spectra and electrical resistance at about 5 and 11 GPa. However, the x-ray diffraction patterns show no structural phase transition in the entire pressure range of the study. The derived pressure-volume (P-V) data show a smooth compression curve with no clear evidence of any second-order phase transition. Fitting the volumetric data to the second-order Birch–Murnaghan equation of state yields V0 = 138.9 ± 0.5 Å3 and K0 = 126 ± 5 GPa.

Crystal structure and the equation of state of thorium monophosphide for pressures up to 50 GPa

1989 ◽  
Vol 22 (1) ◽  
pp. 61-63 ◽  
Author(s):  
J. S. Olsen ◽  
L. Gerward ◽  
U. Benedict ◽  
H. Luo ◽  
O. Vogt
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
High Pressure ◽  
Synchrotron Radiation ◽  
Diamond Anvil Cell ◽  
X Ray Diffraction ◽  
Pressure Derivative ◽  
X Ray ◽  
Cscl Structure ◽  
Diamond Anvil

High-pressure X-ray diffraction studies have been performed on ThP using synchrotron radiation and a diamond-anvil cell. The bulk modulus B 0 and its pressure derivative B′0 have been determined (B 0 = 137 GPa; B′0 = 5.1). A phase transition from the NaCl structure to the CsCl structure was observed at about 30 GPa.

scholarly journals The solvothermal synthesis of γ-AlOOH nanoflakes and their compression behaviors under high pressures

RSC Advances ◽  
2017 ◽  
Vol 7 (9) ◽  
pp. 4904-4911 ◽  
Author(s):  
Xudong Zhou ◽  
Jian Zhang ◽  
Yanmei Ma ◽  
Hui Tian ◽  
Yue Wang ◽  
...  
Keyword(s):  
High Pressure ◽  
Synchrotron Radiation ◽  
Solvothermal Synthesis ◽  
High Pressures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Radiation Angle

The compression behaviors of γ-AlOOH nanoflakes were investigated via in situ high pressure synchrotron radiation angle dispersive X-ray diffraction techniques.

High pressure phase transition in metallic LaB6: Raman and X-ray diffraction studies

2004 ◽  
Vol 129 (12) ◽  
pp. 791-796 ◽  
Author(s):  
Pallavi Teredesai ◽  
D.V.S. Muthu ◽  
N. Chandrabhas ◽  
S. Meenakshi ◽  
V. Vijayakumar ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
High Pressure Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Pressure Phase Transition ◽  
Pressure Phase

Local and long-range order in ferroelastic lead phosphate at high pressure

2004 ◽  
Vol 60 (1) ◽  
pp. 1-9 ◽  
Author(s):  
R. J. Angel ◽  
U. Bismayer ◽  
W. G. Marshall
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Single Crystal ◽  
Local Structure ◽  
High Pressures ◽  
X Ray Diffraction ◽  
Lead Phosphate ◽  
Pure Lead ◽  
Trigonal Symmetry ◽  
X Ray

Pure lead phosphate, Pb3(PO4)2, undergoes a phase transition from C2/c to R\bar 3m symmetry at a pressure of approximately 1.8 GPa and room temperature. Single-crystal X-ray diffraction measurements of the unit-cell parameters of a sample doped with 1.6% Ba2+ for the Pb2+ indicates that the doping reduces the transition pressure by approximately 0.1 GPa. The structural evolution of both samples through the phase transition has been determined by Rietveld refinement of neutron powder diffraction data collected to pressures of 6.3 and 3.3 GPa, respectively. There is no evidence for any significant change in the local structure at the phase transition at high pressures; the structure of the R\bar 3m phase at pressures just above the phase transition includes disordered positions for several atoms. The observation of diffuse scattering from the R\bar 3m phase at high pressure by single-crystal X-ray diffraction suggests that the disorder is static and arises from the presence of several orientations of the ordered microdomains of the monoclinic local structure. The macroscopic transition from monoclinic to trigonal symmetry therefore appears to correspond to the pressure at which the coherency strains between the locally monoclinic microdomains are sufficient to create a dimensionally trigonal lattice within which local displacements of atoms are still significant. A further pressure increase then decreases the magnitude of these displacements until at 3.5 GPa or higher they are not detectable by our current experimental probes, and the structure appears to have true local and global trigonal symmetry.

High pressure phase transitions in organic solids II: X-ray diffraction study ofp-dichlorobenzene at high pressures

Pramana ◽  
1986 ◽  
Vol 27 (6) ◽  
pp. 835-839 ◽  
Author(s):  
Hema Sankaran ◽  
Surinder M Sharma ◽  
S K Sikka ◽  
R Chidambaram
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Diffraction Study ◽  
High Pressures ◽  
High Pressure Phase ◽  
X Ray Diffraction ◽  
Organic Solids ◽  
X Ray ◽  
Pressure Phase
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