scholarly journals Compressibility of synthetic Mg-Al tourmalines to 60 GPa

2019 ◽  
Vol 104 (7) ◽  
pp. 1005-1015 ◽  
Author(s):  
Eleanor J. Berryman ◽  
Dongzhou Zhang ◽  
Bernd Wunder ◽  
Thomas S. Duffy
Keyword(s):  
High Pressure ◽  
Ring Structure ◽  
Primary Control ◽  
Ambient Conditions ◽  
Cell Parameters ◽  
Al Content ◽  
Tour Maline ◽  
Diamond Anvil ◽  
Diffraction Patterns ◽  
Volume Equation

Abstract High-pressure single-crystal X-ray diffraction patterns on five synthetic Mg-Al tourmalines with near end-member compositions [dravite NaMg3Al6Si6O18(BO3)3(OH)3OH, K-dravite KMg3Al6Si6O18(BO3)3(OH)3OH, magnesio-foitite □(Mg2Al)Al6Si6O18(BO3)3(OH)3OH, oxy-uvite CaMg3Al6Si6O18(BO3)3(OH)3O, and olenite NaAl3Al6Si6O18(BO3)3O3OH, where □ represents an X-site vacancy] were collected to 60 GPa at 300 K using a diamond-anvil cell and synchrotron radiation. No phase transitions were observed for any of the investigated compositions. The refined unit-cell parameters were used to constrain third-order Birch-Murnaghan pressure-volume equation of states with the following isothermal bulk moduli (K0 in GPa) and corresponding pressure derivatives (K0′ = ∂K0/∂P)T: dravite K0 = 97(6), K0′ = 5.0(5); K-dravite K0 = 109(4), K0′ = 4.3(2); oxy-uvite K0 = 110(2), K0′ = 4.1(1); magnesio-foitite K0 = 116(2), K0′ = 3.5(1); olenite K0 = 116(6), K0′ = 4.7(4). Each tour-maline exhibits highly anisotropic behavior under compression, with the c axis 2.8–3.6 times more compressible than the a axis at ambient conditions. This anisotropy decreases strongly with increasing pressure and the c axis is onlŷ14% more compressible than the a axis near 60 GPa. The octahedral Y- and Z-sites' composition exerts a primary control on tourmaline's compressibility, whereby Al content is correlated with a decrease in the c-axis compressibility and a corresponding increase in K0 and K0′. Contrary to expectations, the identity of the X-site-occupying ion (Na, K, or Ca) does not have a demonstrable effect on tourmaline's compression curve. The presence of a fully vacant X site in magnesio-foitite results in a decrease of K0′ relative to the alkali and Ca tourmalines. The decrease in K0′ for magnesio-foitite is accounted for by an increase in compressibility along the a axis at high pressure, reflecting increased compression of tourmaline's ring structure in the presence of a vacant X site. This study highlights the utility of synthetic crystals in untangling the effect of composition on tourmaline's compression behavior.

Microporous crystal structure of labuntsovite-Fe and high-pressure behavior up to 23 GPa

2018 ◽  
Vol 74 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Sergey M. Aksenov ◽  
Elena A. Bykova ◽  
Ramiza K. Rastsvetaeva ◽  
Nikita V. Chukanov ◽  
Irina P. Makarova ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Single Crystal ◽  
Cross Section ◽  
Structure Refinement ◽  
Alkaline Complex ◽  
X Ray ◽  
Cell Parameters ◽  
Diamond Anvil ◽  
The Stability

Labuntsovite-Fe, an Fe-dominant member of the labuntsovite subgroup, was first discovered in the Khibiny alkaline massif on Mt Kukisvumchorr [Khomyakov et al. (2001). Zap. Vseross. Mineral. Oba, 130, 36–45]. However, no data are published about the crystal structure of this mineral. Labuntsovite-Fe from a peralkaline pegmatite located on Mt Nyorkpakhk, in the Khibiny alkaline complex, Kola Peninsula, Russia, has been investigated by means of electron microprobe analyses, single-crystal X-ray structure refinement, and IR and Raman spectroscopies. Monoclinic unit-cell parameters of labuntsovite-Fe are: a = 14.2584 (4), b = 13.7541 (6), c = 7.7770 (2) Å, β = 116.893 (3)°; V = 1360.22 (9) Å3; space group C2/m. The structure was refined to final R 1 = 0.0467, wR 2 = 0.0715 for 3202 reflections [I > 3σ(I)]. The refined crystal chemical formula is (Z = 2): Na2K2Ba0.7[(Fe0.5Ti0.1Mg0.05)(H2O)1.3]{[Ti2(Ti1.9Nb0.1)(O,OH)4][Si4O12]2}·4H2O. The high-pressure in situ single-crystal X-ray diffraction study of the labuntsovite-Fe has been carried out in a diamond anvil cell. The labuntsovite-type structure is stable up to 23 GPa and phase transitions are not observed. Calculations using the BM3 equation of state resulted in the bulk modulus K = 72 (2) GPa, K′0 = 3.7 (2) and V 0 = 1363 (2) Å3. Compressing of the heteropolyhedral zeolite-like framework leads to the deformation of main structural units. Octahedral rods show the gradual increase of distortion and the wave-like character of rods becomes more distinct. Rod deformations result in the distortion of the silicon–oxygen ring which is not equal in different directions. Structural channels are characterized by a different ellipticity–pressure relationship: the cross-section of the largest channel I and channel II demonstrates the stability of the geometrical characteristics which practically do not depend on pressure: ∊channel I ≃ 0.85 (4) (cross-section is rather regular) and ∊channel II ≃ 0.52 (2) within the whole pressure range. However, channel III is characterized by the increasing of ellipticity with pressure (∊ = 0.40 → 0.10).

The Use of Quartz as an Internal Pressure Standard in High-Pressure Crystallography

1997 ◽  
Vol 30 (4) ◽  
pp. 461-466 ◽  
Author(s):  
R. J. Angel ◽  
D. R. Allan ◽  
R. Miletich ◽  
L. W. Finger
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Order Equation ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Third Order ◽  
Single Crystal Diffraction ◽  
Cell Parameters ◽  
Diamond Anvil ◽  
Pressure Standard

The unit-cell parameters of quartz, SiO2, have been determined by single-crystal diffraction at 22 pressures to a maximum pressure of 8.9 GPa (at room temperature) with an average precision of 1 part in 9000. Pressure was determined by the measurement of the unit-cell volume of CaF2 fluorite included in the diamond-anvil pressure cell. The variation of quartz unit-cell parameters with pressure is described by: a −4.91300 (11) = −0.0468 (2) P + 0.00256 (7) P 2 − 0.000094 (6) P 3, c − 5.40482 (17) = − 0.03851 (2) P + 0.00305 (7) P 2 − 0.000121 (6) P 3, where P is in GPa and the cell parameters are in ångstroms. The volume–pressure data of quartz are described by a Birch–Murnaghan third-order equation of state with parameters V 0 = 112.981 (2) å3, K T0 = 37.12 (9) GPa and K′ = 5.99 (4). Refinement of K′′ in a fourth-order equation of state yielded a value not significantly different from the value implied by the third-order equation. The use of oriented quartz single crystals is proposed as an improved internal pressure standard for high-pressure single-crystal diffraction experiments in diamond-anvil cells. A measurement precision of 1 part in 10 000 in the volume of quartz leads to a precision in pressure measurement of 0.009 GPa at 9 GPa.

The crystal structure of wolframite type tungstates at high pressure

1993 ◽  
Vol 207 (2) ◽  
Author(s):  
J. Macavei ◽  
H. Schulz
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Standard Deviation ◽  
Diamond Anvil Cell ◽  
Scheelite Structure ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Heavy Atoms ◽  
Structure Determinations ◽  
Diamond Anvil

AbstractSingle-crystal structure determinations of wolframite-type structures were performed using a diamond anvil cell with beryllium gaskets. Unit cell parameters of MgWOAll investigated compounds compress anisotropically with theIn all compounds, the WOWith increasing pressure the oxygen atomic positions remain constant within one standard deviation, while the heavy atoms positions show a different pressure dependence: a shift ofWith increasing pressure the A and W cations approach each other, indicating a tendency of a transition from the wolframite structure to the scheelite structure, where the A and W cations lie in the same plane.

C60 Transformations at High Pressures

1992 ◽  
Vol 270 ◽  
Author(s):  
C. S. Yoo ◽  
W. J. Nellis ◽  
M. L. Sattler ◽  
R. G. Musket ◽  
N. Hinsey ◽  
...  
Keyword(s):  
Thin Films ◽  
High Pressure ◽  
Pressure Range ◽  
High Pressures ◽  
Amorphous State ◽  
Ambient Conditions ◽  
Carbon Phase ◽  
Large Pressure ◽  
Diffraction Patterns ◽  
Intermolecular Distances

ABSTRACTC60 molecules have been studied at both shock and static high pressures. Under shock compressions C60 fullerenes are stable into the 13-17 GPa pressure range. The onset of a fast (∼0.5 μs) reconstructive transformation to graphite occurs near 17 GPa. The graphite recovered from 27 GPa and about 900 K is relatively well ordered with La = 100 Å. Above 50 GPa a continuous transformationto an amorphous state is observed in recovered specimens. A transparent, metastable carbon phase was recovered from thin films of C60, shocked to 69 GPa and 2200 K and then rapidly quenched to 1000 K. The selected area diffraction patterns indicate thatthe metastable carbon contains an amorphous diamond and n-diamond. Under hydrostatic compressions C60 molecules transform reversibly to a semi-transparent phase in the pressure range of 15-25 GPa with a large pressure hysteresis. The high pressure phaseconsists of interconnected strongly interacting C60 agglomerates, or networksof fullerenes, whose stability continuously increases with increase of pressure. Above 27 GPa the transition becomes irreversible, and the material recovered from high pressureis metastable and diamond-like at ambient conditions. These pressure-induced transitions are explained in terms of nr-electron rehybridization between C60 molecules, which occurs at substantially decreased intermolecular distances.

High-quality structures at high pressure? Insights from inclusions in diamonds

2016 ◽  
Vol 231 (8) ◽  
Author(s):  
Ross J. Angel ◽  
Sula Milani ◽  
Matteo Alvaro ◽  
Fabrizio Nestola
Keyword(s):  
High Pressure ◽  
Single Crystal ◽  
High Pressures ◽  
Dominant Factor ◽  
Good Precision ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Experimental Protocols ◽  
Diamond Anvil

AbstractWe describe the experimental protocols necessary to measure the crystal structures of minerals trapped within diamonds by single-crystal X-ray diffraction to the same quality as obtained from minerals studied at ambient conditions. The results show that corrections for X-ray absorption in complex cases can be made with good precision. Comparison of the refined structure of a single-crystal olivine inclusion inside a diamond with the structure of a similar olivine held in a high-pressure diamond-anvil cell shows that data resolution, not the correction for absorption effects, is the dominant factor in influencing the quality of structures determined at high pressures by single-crystal X-ray diffraction.

scholarly journals High-Pressure Raman Spectroscopy and X-ray Diffraction Study on Scottyite, BaCu2Si2O7

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 608
Author(s):  
Pei-Lun Lee ◽  
Eugene Huang ◽  
Jennifer Kung
Keyword(s):  
High Pressure ◽  
Vibration Modes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Raman Spectroscopic ◽  
Diamond Anvil ◽  
Compression Data ◽  
Diffraction Patterns ◽  
Murnaghan Equation

In situ high-pressure synchrotron X-ray diffraction and Raman spectroscopic experiments of scottyite, BaCu2Si2O7, were carried out in a diamond anvil cell up to 21 GPa at room temperature. X-ray diffraction patterns reveal four new peaks near 3.5, 3.1, 2.6 and 2.2 Å above 8 GPa, while some peaks of the original phase disappear above 10 GPa. In the Raman experiment, we observed two discontinuities in dν/dP, the slopes of Raman wavenumber (ν) of some vibration modes versus pressure (P), at approximately 8 and 12 GPa, indicating that the Si-O symmetrical and asymmetrical vibration modes change with pressure. Fitting the compression data to Birch–Murnaghan equation yields a bulk modulus of 102 ± 5 GPa for scottyite, assuming Ko′ is four. Scottyite shows anisotropic compressibility along three crystallographic axes, among which c-axis was the most compressible axis, b-axis was the last and a-axis was similar to the c-axis on the compression. Both X-ray and Raman spectroscopic data provide evidences that scottyite undergoes a reversible phase transformation at 8 GPa.

Optimizing high-pressure pair distribution function measurements in diamond anvil cells

2010 ◽  
Vol 43 (2) ◽  
pp. 297-307 ◽  
Author(s):  
Karena W. Chapman ◽  
Peter J. Chupas ◽  
Gregory J. Halder ◽  
Joseph A. Hriljac ◽  
Charles Kurtz ◽  
...  
Keyword(s):  
High Pressure ◽  
Distribution Function ◽  
Pair Distribution Function ◽  
Scattering Data ◽  
High Quality ◽  
Cell Parameters ◽  
Diamond Anvil ◽  
Target Pressure ◽  
High Pressure Phenomena ◽  
Detector Type

Pair distribution function (PDF) methods have great potential for the study of diverse high-pressure phenomena. However, the measurement of high-quality, high-resolution X-ray PDF data (toQmax > 20 Å−1) remains a technical challenge. An optimized approach to measuring high-pressure total scattering data for samples contained within a diamond anvil cell (DAC) is presented here. This method takes into account the coupled influences of instrument parameters (photon energy, detector type and positioning, beam size/shape, focusing), pressure-cell parameters (target pressure range, DAC type, diamonds, pressure-transmitting media, backing plates, pressure calibration) and data reduction on the resulting PDF. The efficacy of our approach is demonstrated by the high-quality, high-pressure PDFs obtained for representative materials spanning strongly and weakly scattering systems, and crystalline and amorphous samples. These are the highest-resolution high-pressure PDFs reported to date and include those for α-alumina (toQmax  =  20 Å−1), BaTiO3(toQmax= 30 Å−1) and pressure-amorphized zeolite (toQmax  =  20 Å−1).

In situ Raman spectroscopic studies of FeS2 pyrite up to 675 K and 2100 MPa using a hydrothermal diamond anvil cell

2015 ◽  
Vol 79 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Xueyin Yuan ◽  
Haifei Zheng
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Diamond Anvil Cell ◽  
High Pressures ◽  
Quadratic Functions ◽  
Positive Pressure ◽  
Ambient Conditions ◽  
Temperature Conditions ◽  
Diamond Anvil ◽  
Fes2 Pyrite

AbstractRaman scattering experiments of natural FeS2 pyrite were performed at simultaneous high-pressure and high-temperature conditions up to 675 K and 2100 MPa using a hydrothermal diamond anvil cell combined with micro-Raman spectroscopy. Four out of five Raman active modes [Eg, Ag, Tg(1) and Tg(3)] were resolved at ambient conditions, the remaining Tg(2) [∼377 cm–1] mode was weak and unresolved occurring ∼2 cm–1 from the intense Ag [379 cm–1] mode. The frequency shifts of the Eg [343 cm–1] and Ag [379 cm–1] modes were determined to be quadratic functions of pressure and temperature: ν343 = 343.35 – 0.0178 × ΔT – 8.4E – 6 × (ΔT)2 + 0.00367 × Δp 3.7E–7 × (Δp)2 + 1.0E–6 × ΔT × Δp and ν379 = 379.35 – 0.0295 × ΔT – 9.0E–6 × (ΔT)2 + 0.00460 × Δp – 5.3E–7 × (Δp)2 + 7.0E–7 × ΔT × Δp. The positive pressure dependence of both modes indicates stress-induced contraction of S–S and Fe–S bonds, whereas the negative temperature dependence shows temperature-induced expansion of them. The Raman spectra of pyrite were used to derive its bulk modulus at high temperatures, thermal expansion coefficient at high pressures and anharmonic parameters at high-pressure and high-temperature conditions.

First high-pressure XAFS results at the bending-magnet-based energy-dispersive XAFS beamline BL-8 at the Indus-2 synchrotron facility

2020 ◽  
Vol 27 (4) ◽  
pp. 988-998
Author(s):  
Debdutta Lahiri ◽  
Ashutosh Dwivedi ◽  
R. Vasanthi ◽  
S. N. Jha ◽  
Nandini Garg
Keyword(s):  
High Pressure ◽  
Spot Size ◽  
Energy Dispersive ◽  
Photon Statistics ◽  
Ambient Conditions ◽  
Slit Position ◽  
Synchrotron Facility ◽  
Sample Position ◽  
Diamond Anvil ◽  
Selection Of

The static focusing optics of the existing energy-dispersive XAFS beamline BL-8 have been advantageously exploited to initiate diamond anvil cell based high-pressure XANES experiments at the Indus-2 synchrotron facility, India. In the framework of the limited photon statistics with the 2.5 GeV bending-magnet source, limited focusing optics and 4 mm-thick diamond windows of the sample cell, a (non-trivial) beamline alignment method for maximizing photon statistics at the sample position has been designed. Key strategies include the selection of a high X-ray energy edge, the truncation of the smallest achievable focal spot size to target size with a slit and optimization of the horizontal slit position for transmission of the desired energy band. A motor-scanning program for precise sample centering has been developed. These details are presented with rationalization for every step. With these strategies, Nb K-edge XANES spectra for Nb2O5 under high pressure (0–16.9 GPa) have been generated, reproducing the reported spectra for Nb2O5 under ambient conditions and high pressure. These first HPXANES results are reported in this paper. The scope of extending good data quality to the EXAFS range in the future is addressed. This work should inspire and guide future high-pressure XAFS experiments with comparable infrastructure.

scholarly journals High-pressure crystal chemistry of coesite-I and its transition to coesite-II

2014 ◽  
Vol 229 (11) ◽  
Author(s):  
Ana Černok ◽  
Elena Bykova ◽  
Tiziana Boffa Ballaran ◽  
Hanns-Peter Liermann ◽  
Michael Hanfland ◽  
...  
Keyword(s):  
High Pressure ◽  
Synchrotron Radiation ◽  
Crystal Chemistry ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Diamond Anvil ◽  
Pressure Interval

AbstractThe high-pressure crystal chemistry of coesite was studied by means of single crystal X-ray diffraction in the pressure interval ∼2–34 GPa and at ambient temperature. We compressed the samples using diamond-anvil cells loaded with neon as pressure-transmitting medium and collected X-ray diffraction data using synchrotron radiation. The thermodynamically stable coesite – coesite-I – was observed up to ∼20 GPa, with the following unit-cell parameters:

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