Structure of a high-pressure phase of vanadium pentoxide, β-V2O5

2004 ◽  
Vol 60 (4) ◽  
pp. 375-381 ◽  
Author(s):  
V. P. Filonenko ◽  
M. Sundberg ◽  
P.-E. Werner ◽  
I. P. Zibrov
Keyword(s):  
High Pressure ◽  
Vanadium Pentoxide ◽  
Layer Structure ◽  
Ambient Pressure ◽  
High Pressure Phase ◽  
X Ray ◽  
Transmission Electron ◽  
Structural Relationships ◽  
Oxide Bronzes ◽  
Pressure Phase

A high-pressure phase of vanadium pentoxide, denoted β-V2O5, has been prepared at P = 6.0 GPa and T = 1073 K. The crystal structure of β-V2O5 has been studied by X-ray and neutron powder diffraction, and high-resolution transmission electron microscopy. The V atoms are six-coordinated within distorted VO6 octahedra. The structure is built up of quadruple units of edge-sharing VO6 octahedra linked by sharing edges along [010] and mutually connected by sharing corners along [001]. This arrangement forms layers of V4O10 composition in planes parallel to (100). The layers are mutually held together by weak forces. β-V2O5 is metastable and transforms to α-V2O5 at 643–653 K under ambient pressure. Structural relationships between β- and α-V2O5, and between β-V2O5 and B-Ta2O5-type structures are discussed. The high-pressure β-V2O5 layer structure can be considered as the parent of a new series of vanadium oxide bronzes with cations intercalated between the layers.

High-pressure synthesis and crystal structure of the strontium tungstate Sr3W2O9

2018 ◽  
Vol 74 (2) ◽  
pp. 120-124 ◽  
Author(s):  
Daisuke Urushihara ◽  
Toru Asaka ◽  
Koichiro Fukuda ◽  
Hiroya Sakurai
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
High Pressure Phase ◽  
X Ray Diffraction ◽  
Rotation Symmetry ◽  
Synthesis And Crystal Structure ◽  
High Pressure Synthesis ◽  
Transmission Electron ◽  
Pressure Synthesis ◽  
Pressure Phase

The strontium tungstate compound Sr3W2O9 was prepared by a high-pressure synthesis technique. The crystal structure was determined by single-crystal X-ray diffraction and transmission electron microscopy. The structure was found to be a hettotype structure of the high-pressure phase of Ba3W2O9, which has corner-sharing octahedra with a trigonal symmetry. Sr3W2O9 has a monoclinic unit cell of C2/c symmetry. One characteristic of the structure is the breaking of the threefold rotation symmetry existing in the high-pressure phase of Ba3W2O9. The substitution of Sr at the Ba site results in a significant shortening of the interlayer distances of the [AO3] layers (A = Ba, Sr) and causes a distortion in the crystal structure. In Sr3W2O9, there is an off-centre displacement of W6+ ions in the WO6 octahedra. Such a displacement is also observed in the high-pressure phase of Ba3W2O9.

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 Synthesis and Crystal Structure of the New Orthorhombic Polymorph β-HgB4O7

2005 ◽  
Vol 60 (8) ◽  
pp. 815-820 ◽  
Author(s):  
Holger Emme ◽  
Matthias Weil ◽  
Hubert Huppertz
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Ambient Pressure ◽  
Normal Pressure ◽  
High Pressure Phase ◽  
Synthesis And Crystal Structure ◽  
Space Group ◽  
High Pressure Synthesis ◽  
Pressure Synthesis ◽  
Pressure Phase

The new orthorhombic polymorph β-HgB4O7 has been synthesized under high-pressure and hightemperature conditions in a Walker-type multianvil apparatus at 7.5 GPa and 600 °C. β-HgB4O7 is isotypic to the known ambient pressure phases MB4O7 (M = Sr, Pb, Eu) and the high-pressure phase β-CaB4O7 crystallizing with two formula units in the space group Pmn21 with lattice parameters a = 1065.6(2), b = 438.10(9), and c = 418.72(8) pm. The relation of the crystal structure of the high-pressure phase β-HgB4O7 to the normal pressure phase α-HgB4O7 as well as the relation to the isotypic phases MB4O7 (M = Sr, Pb, Eu) and β-CaB4O7 are discussed.

High-pressure phase transition in Al(OH)3: Raman and X-ray observations

1996 ◽  
Vol 23 (22) ◽  
pp. 3083-3086 ◽  
Author(s):  
Eugene Huang ◽  
Alice Li ◽  
Ji-an Xu ◽  
Rong-Jer Chen ◽  
Takamitsu Yamanaka
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
High Pressure Phase ◽  
X Ray ◽  
High Pressure Phase Transition ◽  
Pressure Phase

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
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