scholarly journals High-pressure structural investigation of several zircon-type orthovanadates

2009 ◽  
Vol 79 (18) ◽  
Author(s):  
D. Errandonea ◽  
R. Lacomba-Perales ◽  
J. Ruiz-Fuertes ◽  
A. Segura ◽  
S. N. Achary ◽  
...  
Keyword(s):  
High Pressure ◽  
Structural Investigation ◽  
Zircon Type

Structural investigation of high-tc superconductors under high pressure

1990 ◽  
Vol 4 (1-6) ◽  
pp. 423-425 ◽  
Author(s):  
W. H. Fietz ◽  
C. A. Wassilew ◽  
H. A. Ludwig ◽  
B. Obst ◽  
C. Politis ◽  
...  
Keyword(s):  
High Pressure ◽  
Structural Investigation ◽  
High Tc Superconductors ◽  
High Tc

Structural investigation of ribonuclease A conformational preferences using high pressure protein crystallography

2016 ◽  
Vol 468 ◽  
pp. 53-62 ◽  
Author(s):  
Katarzyna Kurpiewska ◽  
Kamil Dziubek ◽  
Andrzej Katrusiak ◽  
Josep Font ◽  
Marc Ribò ◽  
...  
Keyword(s):  
High Pressure ◽  
Structural Investigation ◽  
Protein Crystallography ◽  
Ribonuclease A ◽  
Conformational Preferences

On the role of U/ThO8 polyhedral distortions in controlling the high-pressure zircon→reidite type transition in UxTh1-xO4

2020 ◽  
Author(s):  
Sudip Kumar Mondal
Keyword(s):  
Phase Transition ◽  
Solid Solution ◽  
High Pressure ◽  
Structural Phase ◽  
Angular Distortion ◽  
Research Centre ◽  
Transition Pressure ◽  
Type Transition ◽  
Zircon Type

<p><strong>On the role of U/ThO<sub>8 </sub>polyhedral distortions in controlling the high-pressure zircon→reidite type transition in U<sub>x</sub>Th<sub>1-x</sub>O<sub>4</sub></strong></p><p> </p><p>Sudip Kumar Mondal<sup>1<strong>,</strong>2</sup>, Pratik Kr Das<sup>2<strong>,</strong>3</sup>, Nibir Mandal<sup>2</sup> and Ashok Arya<sup>4</sup><br>1 Department of Physics, Jadavpur University, Kolkata 700032, India<br>2 Faculty of Science, High Pressure and Temperature Laboratory, Jadavpur University, Kolkata 700032, India<br>3 The Centre for Earth Evolution and Dynamics, University of Oslo, Oslo, N-0315, Norway<br>4 Material Science Division, Bhabha Atomic Research Centre, Mumbai 400085, India</p><p> </p><p>Coffinite (USiO<sub>4</sub>) and thorite (ThSiO<sub>4</sub>) are conspicuous radiogenic silicates in the geonomy. They form U<sub>1</sub><sub>-</sub><sub>x</sub>Th<sub>x</sub>SiO<sub>4</sub> (uranothorite) solid solutions in zircon-type phase. Investigating the phase-evolution of these minerals is of utmost significance in realizing their applicability in the front-as well as at the back-end of nuclear industries and also from geological perspective, such as geochronology. We carried out a systematic study of zircon- to reidite-type (tetragonal I41/amd to I41/a) structural transitions of U<sub>1</sub><sub>-</sub><sub>x</sub>Th<sub>x</sub>SiO<sub>4 </sub>solid solution, and investigated their mechanical behaviour. Our ab-initio calculations revealed a unique interconnection of phase transition pressure (p<sub>t</sub>) with the change in U-Th concentration in the solid solution. The transition pressure is found to be minimum (6.82 GPa) for x = 0.5 whereas for the endmembers coffinite and thorite p<sub>t</sub>’s are 8.52 and 8.68 GPa, respectively. We developed a novel method to estimate the longitudinal and angular distortions of the highly irregular U/ThO<sub>8</sub>-triangular dodecahedra (snub-disphenoids). We have parameterized two new factors: δ (longitudinal distortions) and σ<sup>2</sup> (angular distortions) to quantify the polyhedral distortions. A detailed analysis of the snub-disphenoidal distortions demonstrates that the difference in angular distortion of UO<sub>8</sub> and ThO<sub>8</sub> polyhedra (i.e. σ<sub>U</sub><sup>2 </sup>and σ<sub>Th</sub><sup>2</sup>) between zircon- and  reidite-type phases becomes minimum when U and Th percentage are equal, leading to the structural phase transition at the minimum hydrostatic pressure for the unique chemical composition: U<sub>0.5</sub>Th<sub>0.5</sub>SiO<sub>4</sub>. Our result is also substantiated by the minimum compressibility observed for the zircon-type U<sub>0.5</sub>Th<sub>0.5</sub>SiO<sub>4</sub>. It is worthwhile to note that the distortions parameters, δ and σ<sup>2</sup> are defined without any attribute to external parameters. They are also independent to the elements occupying the polyhedra. Thus, we propose that these parameters: δ and σ<sup>2</sup> can also be used to calculate the distortions of similar AB<sub>8</sub>-type snub-disphenoids observed in zircon-, reidite-, fergusonite- and wolframite-type mineral phases.</p>

Hochdruckumwandlungen von Cer(III)Orthovanadat(V), CeVO4 / High-Pressure Transformations of Cerium(III) Orthovanadate(V), CeVO4

1990 ◽  
Vol 45 (5) ◽  
pp. 598-602 ◽  
Author(s):  
Klaus-Jürgen Range ◽  
Helmut Meister ◽  
Ulrich Klement
Keyword(s):  
High Pressure ◽  
Triple Point ◽  
High Pressures ◽  
Its Region ◽  
Normal Pressure ◽  
Crystal Data ◽  
High Pressures And Temperatures ◽  
Zircon Type ◽  
High Pressure Apparatus

The polymorphism of CeVO4 was investigated at high pressures and temperatures in a Belttype high-pressure apparatus. In addition to the normal-pressure modification CeVO4— I with zircon-type structure two high-pressure modifications have been found, viz. monazite-type CeVO4—II and scheelite-type CeVO4—III. CeVO4—II is stable between 1 bar and 30 kbar at 1300 °C. Its region of existence decreases rapidly at lower temperatures. From the observed p,T-relations for the I-II and I-III transformations a triple point CeVO4—I,II,III at about 27 kbar, 500 °C can be estimated. For kinetic reasons, however, the experimental determination of phase relations becomes difficult at temperatures below 600 °C.The crystal structures of CeVO4— I and —II have been refined from single-crystal data. Crystallographic data for the three modifications are given and discussed (CeVO4—I: I 41/amd, a = 7.383(1)Å, c = 6.485(1)Å, Z = 4; CeVO4—II: P21/n, a = 7.003(1)Å, b = 7.227(1)Å, c = 6.685(1)Å, β = 105.13(1)°, Z = 4; CeVO4—III: I 41/α, a = 5.1645(2)Å, c = 11.8482(7)Å, Z = 4).

scholarly journals The electronic structure of zircon-type orthovanadates: Effects of high-pressure and cation substitution

2011 ◽  
Vol 110 (4) ◽  
pp. 043723 ◽  
Author(s):  
V. Panchal ◽  
D. Errandonea ◽  
A. Segura ◽  
P. Rodríguez-Hernandez ◽  
A. Muñoz ◽  
...  
Keyword(s):  
High Pressure ◽  
Electronic Structure ◽  
Cation Substitution ◽  
Zircon Type

Lattice dynamics of zircon-type NdVO4 and scheelite-type PrVO4 under high-pressure

2021 ◽  
Author(s):  
Tomás Marqueño ◽  
Julio Pellicer-Porres ◽  
Daniel Errandonea ◽  
David Santamaria-Perez ◽  
Domingo Martinez-Garcia ◽  
...  
Keyword(s):  
High Pressure ◽  
Lattice Dynamics ◽  
Zircon Type

High-pressure structural investigation of ferromagneticNd2Mo2O7

2004 ◽  
Vol 70 (10) ◽  
Author(s):  
H. Ishikawa ◽  
Sh. Xu ◽  
Y. Moritomo ◽  
A. Nakamura ◽  
Y. Ohishi ◽  
...  
Keyword(s):  
High Pressure ◽  
Structural Investigation
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