Elasticity and high-pressure structure of arsenoflorencite-(La): insights into the high-pressure behaviour of the alunite supergroup

2012 ◽  
Vol 76 (4) ◽  
pp. 975-985 ◽  
Author(s):  
S. J. Mills ◽  
F. Nestola
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Phase Transformation ◽  
Volume Data ◽  
Third Order ◽  
X Ray ◽  
Compression Mechanism ◽  
Internal Angle ◽  
Murnaghan Equation ◽  
First Time

AbstractArsenoflorencite-(La), ideally LaAl3(AsO4)2(OH)6, was studied at high pressure by single-crystal X-ray diffractometry. The unit cell was determined at nine pressures up to 7.471(8) GPa; no evidence of a phase transformation was found in this range. The pressure volume data (refined simultaneously) were fitted to a third-order Birch Murnaghan equation of state which gave V0 = 710.71(8) Å3, KT0 = 106(2) GPa and K' = 9.2(9). These values were confirmed independently from an FE–fE plot. The crystal structure was refined at 1.596, 3.622, 5.749 and 7.471 GPa, the first time this has been done for a member the alunite supergroup. The compressibility of arsenoflorencite-(La) is strongly anisotropic, with βc > βa. The main compression mechanism was found to be governed by the internal angle O3 La O2 of the La polyhedron, where the O2 and O3 atoms move toward the c axis during compression.

Crystal structure, compressibility and possible phase transitions in \boldvarepsilon-FeSi studied by first-principles pseudopotential calculations

1999 ◽  
Vol 55 (4) ◽  
pp. 484-493 ◽  
Author(s):  
Lidunka Vočadlo ◽  
Geoffrey D. Price ◽  
I. G. Wood
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Phase Transitions ◽  
First Principles ◽  
Stable Phase ◽  
Third Order ◽  
First Derivative ◽  
Pseudopotential Calculations ◽  
Cscl Type ◽  
Murnaghan Equation

An investigation of the relative stability of the FeSi structure and of some hypothetical polymorphs of FeSi has been made by first-principles pseudopotential calculations. It has been shown that the observed distortion from ideal sevenfold coordination is essential in stabilizing the FeSi structure relative to one of the CsCl type. Application of high pressure to FeSi is predicted to produce a structure having nearly perfect sevenfold coordination. However, it appears that FeSi having a CsCl-type structure will be the thermodynamically most stable phase for pressures greater than 13 GPa. Fitting of the calculated internal energy vs volume for the FeSi structure to a third-order Birch–Murnaghan equation of state led to values, at T = 0 K, for the bulk modulus, K 0, and for its first derivative with respect to pressure, K 0′, of 227 GPa and 3.9, respectively.

scholarly journals The High Pressure Behavior of Galenobismutite, PbBi2S4: A Synchrotron Single Crystal X-ray Diffraction Study

Crystals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 210 ◽  
Author(s):  
Paola Comodi ◽  
Azzurra Zucchini ◽  
Tonci Balić-Žunić ◽  
Michael Hanfland ◽  
Ines Collings
Keyword(s):  
High Pressure ◽  
Single Crystal ◽  
Structural Changes ◽  
Calcium Ferrite ◽  
X Ray Diffraction ◽  
Third Order ◽  
Electron Pairs ◽  
X Ray ◽  
Cation Sites ◽  
Murnaghan Equation

High-pressure single-crystal synchrotron X-ray diffraction data for galenobismutite, PbBi2S4 collected up to 20.9 GPa, were fitted by a third-order Birch-Murnaghan equation of state, as suggested by a FE-fE plot, yielding V0 = 697.4(8) Å3, K0 = 51(1) GPa and K’ = 5.0(2). The axial moduli were M0a = 115(7) GPa and Ma’ = 28(2) for the a axis, M0b = 162(3) GPa and Mb’ = 8(3) for the b axis, M0c = 142(8) GPa and Mc’ = 26(2) for the c axis, with refined values of a0, b0, c0 equal to 11.791(7) Å, 14.540(6) Å 4.076(3) Å, respectively, and a ratio equal to M0a:M0b:M0c = 1.55:1:1.79. The main structural changes on compression were the M2 and M3 (occupied by Bi, Pb) movements toward the centers of their respective trigonal prism bodies and M3 changes towards CN8. The M1 site, occupied solely by Bi, regularizes the octahedral form with CN6. The eccentricities of all cation sites decreased with compression testifying for a decrease in stereochemical expression of lone electron pairs. Galenobismutite is isostructural with calcium ferrite CaFe2O4, the suggested high pressure structure can host Na and Al in the lower mantle. The study indicates that pressure enables the incorporation of other elements in this structure, increasing its potential significance for mantle mineralogy.

Equation of state of hercynite, FeAl2O4, and high-pressure systematics of Mg-Fe-Cr-Al spinels

2015 ◽  
Vol 79 (2) ◽  
pp. 285-294 ◽  
Author(s):  
F. Nestola ◽  
B. Periotto ◽  
C. Anzolini ◽  
G. B. Andreozzi ◽  
A. B. Woodland ◽  
...  
Keyword(s):  
Equation Of State ◽  
Experimental Approach ◽  
Volume Data ◽  
X Ray Diffraction ◽  
Third Order ◽  
X Ray ◽  
Volume Equation ◽  
Overlap Method ◽  
Pulse Echo ◽  
Murnaghan Equation

AbstractIn this work a single crystal of synthetic hercynite, FeAl2O4, was investigated by X-ray diffraction up to 7.5 GPa and at room temperature, in order to determine its pressure–volume equation of state. The unit-cell volume decreases non-linearly with a reduction of 3.4% (i.e. 18.43 Å3). The pressure–volume data were fitted to a third-order Birch-Murnaghan equation of state providing the following coefficients: V0 = 542.58(3)Å3, KT0 = 193.9(1.7) GPa, K' = 6.0(5). These results are consistent with previous investigations of Cr and Al spinels measured with the same experimental approach but the KT0 differs significantly from the experimental determination carried out more than 40 years ago by Wang and Simmons (1972) by the pulse echo overlap method. Our new results were used to redetermine the FeAl2O4(hercynite) = FeO(wüstite) + Al2O3(corundum) equilibrium in P–T space and obtain geobarometric information for Cr-Al spinels found as inclusions in diamond.

HIGH-PRESSURE STRUCTURE STUDY OF CuBa2Ca3Cu4O10 + δ SUPERCONDUCTOR

2005 ◽  
Vol 19 (06) ◽  
pp. 313-316
Author(s):  
X. M. QIN ◽  
Y. YU ◽  
G. M. ZHANG ◽  
F. Y. LI ◽  
J. LIU ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Room Temperature ◽  
Diamond Anvil Cell ◽  
Structure Study ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diamond Anvil ◽  
Murnaghan Equation

In-situ high-pressure energy dispersive X-ray diffraction measurements on CuBa 2- Ca 3 Cu 4 O 10 + δ (Cu-1234) have been performed by using diamond anvil cell (DAC) device with synchrotron radiation. The results suggest that the crystal structure of Cu-1234 superconductor is stable under pressures up to 34 GPa at room temperature. According to the Birch–Murnaghan equation of state, the bulk modulus is obtained to be ~ 150 GPa.

scholarly journals High Pressure Behavior of Mascagnite from Single Crystal Synchrotron X-ray Diffraction Data

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 976
Author(s):  
Paola Comodi ◽  
Maximiliano Fastelli ◽  
Giacomo Criniti ◽  
Konstantin Glazyrin ◽  
Azzurra Zucchini
Keyword(s):  
High Pressure ◽  
Single Crystal ◽  
Room Temperature ◽  
Diamond Anvil Cell ◽  
Geometrical Parameters ◽  
X Ray Diffraction ◽  
Third Order ◽  
X Ray ◽  
Diamond Anvil ◽  
Murnaghan Equation

High-pressure synchrotron X-ray diffraction was carried out on a single crystal of mascagnite, compressed in a diamond anvil cell. The sample maintained its crystal structure up to ~18 GPa. The volume–pressure data were fitted by a third-order Birch–Murnaghan equation of state (BM3-EOS) yielding K0 = 20.4(7) GPa, K’0 = 6.1(2), and V0 = 499(1) Å3, as suggested by the F-f plot. The axial compressibilities, calculated with BM3-EOS, were K0a = 35(3), K’0a = 7.7(7), K0b = 10(3), K’0b = 7(1), K0c = 25(1), and K’0c = 4.3(2) The axial moduli measured using a BM2-EOS and fixing K’0 equal to 4, were K0a = 52(2), K0b = 20 (1), and K0c = 29.6(4) GPa, and the anisotropic ratio of K0a:K0b:K0c = 1:0.4:0.5. The evolution of crystal lattice and geometrical parameters indicated no phase transition until 17.6 GPa. Sulphate polyhedra were incompressible and the density increase of 30% compared to investigated pressure should be attributed to the reduction of weaker hydrogen bonds. In contrast, some of them, directed along [100], were very short at room temperature, below 2 Å, and showed a very low compressibility. This configuration explains the anisotropic compressional behavior and the lowest compressibility of the a axis.

The alunite supergroup under high pressure: the case of natrojarosite, NaFe3(SO4)2(OH)6

2013 ◽  
Vol 77 (7) ◽  
pp. 3007-3017 ◽  
Author(s):  
F. Nestola ◽  
S. J. Mills ◽  
B. Periotto ◽  
L. Scandolo
Keyword(s):  
High Pressure ◽  
Single Crystal ◽  
Maximum Pressure ◽  
X Ray Diffraction ◽  
Third Order ◽  
X Ray ◽  
Cell Parameters ◽  
Diamond Anvil ◽  
Murnaghan Equation ◽  
Volume Decrease

AbstractA single crystal of natrojarosite, NaFe3(SO4)2(OH)6, was investigated by single-crystal X-ray diffraction at high-pressure conditions (up to 8.8 GPa) using a diamond-anvil cell. The unit-cell parameters were determined at 11 different pressures and no indications of a phase transition were found up to the maximum pressure reached. The volume and axial moduli were fitted to a third-order Birch–Murnaghan equation-of-state which gave the following values: V0 = 769.6(2) Å3, KT0 = 50.6(9) GPa, K' = 9.9(4); a = 7.3172(6) Å, KT0 = 104(2), K' = 7.6(9); c = 16.5965(20) Å, KT0 = 24.6(4) and K' = 7.1(2). The crystal structure of natrojarosite was refined at seven different pressures up to 8.779(11) GPa [a = 7.3170(4), c = 16.5955(5) Å and V = 769.46(9) Å3 in Rm at 0.00010(1) GPa and a = 7.1594(8), c = 15.6003(17) Å and V = 692.49(8) Å3 at 8.779(11) GPa]. The structural analysis shows that the 12-fold Na polyhedron accommodates most of the deformation by a large volume decrease (14%) and strong polyhedral distortion (63%). Our results indicate that natrojarosite has the most compressible structure of the supergroup studied so far, and has a very strong axial anisotropy.

Single Crystal Growth of High-Pressure Phases of Ice and Salt Hydrate Far Below the Original Melting Point by Mixing Alcohol: Crystal Structure Determination of Magnesium Chloride Heptahydrate

2020 ◽  
Author(s):  
Keishiro Yamashita ◽  
Kazuki Komatsu ◽  
Hiroyuki Kagi
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Crystal Growth ◽  
Single Crystal ◽  
Room Temperature ◽  
Growth Technique ◽  
Salt Hydrate ◽  
X Ray

An crystal-growth technique for single crystal x-ray structure analysis of high-pressure forms of hydrogen-bonded crystals is proposed. We used alcohol mixture (methanol: ethanol = 4:1 in volumetric ratio), which is a widely used pressure transmitting medium, inhibiting the nucleation and growth of unwanted crystals. In this paper, two kinds of single crystals which have not been obtained using a conventional experimental technique were obtained using this technique: ice VI at 1.99 GPa and MgCl<sub>2</sub>·7H<sub>2</sub>O at 2.50 GPa at room temperature. Here we first report the crystal structure of MgCl2·7H2O. This technique simultaneously meets the requirement of hydrostaticity for high-pressure experiments and has feasibility for further in-situ measurements.

scholarly journals High-pressure synthesis and crystal structure of the mixed-cation borate Ga4In4B15O33(OH)3

2019 ◽  
Vol 74 (4) ◽  
pp. 357-363
Author(s):  
Daniela Vitzthum ◽  
Hubert Huppertz
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
High Temperature ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Mixed Cation ◽  
High Pressure High Temperature ◽  
Pressure Synthesis

AbstractThe mixed cation triel borate Ga4In4B15O33(OH)3 was synthesized in a Walker-type multianvil apparatus at high-pressure/high-temperature conditions of 12.5 GPa and 1300°C. Although the product could not be reproduced in further experiments, its crystal structure could be reliably determined via single-crystal X-ray diffraction data. Ga4In4B15O33(OH)3 crystallizes in the tetragonal space group I41/a (origin choice 2) with the lattice parameters a = 11.382(2), c = 15.244(2) Å, and V = 1974.9(4) Å3. The structure of the quaternary triel borate consists of a complex network of BO4 tetrahedra, edge-sharing InO6 octahedra in dinuclear units, and very dense edge-sharing GaO6 octahedra in tetranuclear units.

PHASE TRANSITION IN LAYERED PEROVSKITE LIKE MANGANATE Ca3Mn2O7 UNDER HIGH PRESSURE

2001 ◽  
Vol 15 (18) ◽  
pp. 2491-2497 ◽  
Author(s):  
J. L. ZHU ◽  
L. C. CHEN ◽  
R. C. YU ◽  
F. Y. LI ◽  
J. LIU ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Diamond Anvil Cell ◽  
The Other ◽  
Layered Perovskite ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Diamond Anvil

In situ high pressure energy dispersive X-ray diffraction measurements on layered perovskite-like manganate Ca 3 Mn 2 O 7 under pressures up to 35 GPa have been performed by using diamond anvil cell with synchrotron radiation. The results show that the structure of layered perovskite-like manganate Ca 3 Mn 2 O 7 is unstable under pressure due to the easy compression of NaCl-type blocks. The structure of Ca 3 Mn 2 O 7 underwent two phase transitions under pressures in the range of 0~35 GPa. One was at about 1.3 GPa with the crystal structure changing from tetragonal to orthorhombic. The other was at about 9.5 GPa with the crystal structure changing from orthorhombic back to another tetragonal.

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