scholarly journals Phase Transitions in Natural Vanadinite at High Pressures

Minerals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1217
Author(s):  
Yingxin Liu ◽  
Liyun Dai ◽  
Xiaojing Lai ◽  
Feng Zhu ◽  
Dongzhou Zhang ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
High Pressure ◽  
Structural Changes ◽  
High Pressures ◽  
Color Change ◽  
X Ray Diffraction ◽  
Grüneisen Parameters ◽  
Reversible Phase Transition ◽  
Diamond Anvil ◽  
Gruneisen Parameters

The structural stability of vanadinite, Pb5[VO4]3Cl, is reported by high-pressure experiments using synchrotron radiation X-ray diffraction (XRD) and Raman spectroscopy. XRD experiments were performed up to 44.6 GPa and 700 K using an externally-heated diamond anvil cell (EHDAC), and Raman spectroscopy measurements were performed up to 26.8 GPa at room temperature. XRD experiments revealed a reversible phase transition of vanadinite at 23 GPa and 600 K, which is accompanied by a discontinuous volume reduction and color change of the mineral from transparent to reddish during compression. The high-pressure Raman spectra of vanadinite show apparent changes between 18.0 and 22.8 GPa and finally become amorphous at 26.8 GPa, suggesting structural transitions of this mineral upon compression. The structural changes can be distinguished by the emergence of a new vibrational mode that can be attributed to the distortion of [VO4] and the larger distortion of the V–O bonds, respectively. The [VO4] internal modes in vanadinite give isothermal mode Grüneisen parameters varying from 0.149 to 0.286, yielding an average VO4 internal mode Grüneisen parameters of 0.202.

Structural stability of WS2 under high pressure

2014 ◽  
Vol 28 (25) ◽  
pp. 1450168 ◽  
Author(s):  
Nirup Bandaru ◽  
Ravhi S. Kumar ◽  
Jason Baker ◽  
Oliver Tschauner ◽  
Thomas Hartmann ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
High Temperature ◽  
Structural Changes ◽  
High Pressures ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diamond Anvil ◽  
Heating Up

Structural behavior of bulk WS 2 under high pressure was investigated using synchrotron X-ray diffraction and diamond anvil cell up to 52 GPa along with high temperature X-ray diffraction and high pressure Raman spectroscopy analysis. The high pressure results obtained from X-ray diffraction and Raman analysis did not show any pressure induced structural phase transformations up to 52 GPa. The high temperature results show that the WS 2 crystal structure is stable upon heating up to 600°C. Furthermore, the powder X-ray diffraction obtained on shock subjected WS 2 to high pressures up to 10 GPa also did not reveal any structural changes. Our results suggest that even though WS 2 is less compressible than the isostructural MoS 2, its crystal structure is stable under static and dynamic compressions up to the experimental limit.

Examining the structural changes in Fe2(CO)9 under high external pressures by Raman spectroscopy

2007 ◽  
Vol 85 (10) ◽  
pp. 866-872 ◽  
Author(s):  
Muhieddine Safa ◽  
Zhaohui Dong ◽  
Yang Song ◽  
Yining Huang
Keyword(s):  
Raman Spectroscopy ◽  
High Pressure ◽  
Diamond Anvil Cell ◽  
Structural Changes ◽  
High Pressures ◽  
Metal Carbonyl ◽  
In Situ Raman Spectroscopy ◽  
Metal Metal ◽  
Diamond Anvil ◽  
Pressure Phase

Pressure-induced structural changes in di-iron nonacarbonyl [Fe2(CO)9] were examined by in situ Raman spectroscopy with the aid of a diamond anvil cell. Our results indicate that Fe2(CO)9 undergoes a pressure-induced phase transformation at about 0.9 GPa. Upon further compression, another structural transformation is identified at 7 GPa. In the low-pressure phase below 0.9 GPa, the π back-bonding between metal and carbonyl increases with increasing pressure. In the high-pressure phase above 7 GPa, the combination of high-pressure and laser irradiation induces a change in structure from Fe2(CO)9 to Fe2(CO)8. Fe2(CO)8 appears to adopt a structure with C2v rather than D3d or D2h symmetry. The metal–metal bond is gradually weakened under high pressures, and Fe2(CO)8 eventually decomposes by breaking the Fe–Fe bond when compressed up to 17.7 GPa.Key words: metal carbonyl, Raman spectroscopy, high pressure, diamond anvil cell.

p-Aminobenzoic acid polymorphs under high pressures

RSC Advances ◽  
2014 ◽  
Vol 4 (30) ◽  
pp. 15534-15541 ◽  
Author(s):  
Tingting Yan ◽  
Kai Wang ◽  
Defang Duan ◽  
Xiao Tan ◽  
Bingbing Liu ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
High Pressure ◽  
Diamond Anvil Cell ◽  
High Pressures ◽  
Aminobenzoic Acid ◽  
Aminobenzoic Acids ◽  
Diamond Anvil

The effect of high pressure on two forms (α, β) of p-aminobenzoic acids (PABA) is studied in a diamond anvil cell using in situ Raman spectroscopy.

scholarly journals High Pressure Diffraction for the Geosciences at the Advanced Light Source

2014 ◽  
Vol 70 (a1) ◽  
pp. C1097-C1097
Author(s):  
Christine Beavers ◽  
Jason Knight ◽  
Bora Kalkan ◽  
Jinyuan Yan ◽  
Alastair MacDowell ◽  
...  
Keyword(s):  
High Pressure ◽  
Light Source ◽  
High Pressures ◽  
X Rays ◽  
X Ray Diffraction ◽  
User Friendliness ◽  
X Ray ◽  
Advanced Light Source ◽  
Diamond Anvil ◽  
Multiple Detectors

The Advanced Light Source, in concert with COMPRES, supports a superconducting bending magnet beamline devoted to extreme conditions diffraction. This facility, beamline 12.2.2, is aimed at the geoscience community, but is available to any who desire high pressures, high temperatures and hard X-rays. The latest development has been integrating single crystal x-ray diffraction for diamond anvil cells into the existing suite of high pressure powder diffraction and amorphous scattering techniques. Multiple heating techniques are available to the user, as well as multiple detectors, which can be chosen to best suit the sample. The current staff are dedicated to improving the user friendliness of the beamline; a difficult experiment need not to be further complicated by a difficult beamline. Beamline infrastructure, including recent advances and improvements, will be discussed.

scholarly journals High-pressure Seebeck coefficients and thermoelectric behaviors of Bi and PbTe measured using a Paris-Edinburgh cell

2016 ◽  
Vol 23 (6) ◽  
pp. 1368-1378 ◽  
Author(s):  
Jason Baker ◽  
Ravhi Kumar ◽  
Changyong Park ◽  
Curtis Kenney-Benson ◽  
Andrew Cornelius ◽  
...  
Keyword(s):  
High Pressure ◽  
Seebeck Coefficient ◽  
Structural Changes ◽  
High Pressures ◽  
Solid Phase ◽  
Thermal Conductance ◽  
X Ray Diffraction ◽  
Seebeck Coefficients ◽  
Assembly Design ◽  
Relative Change

A new sample cell assembly design for the Paris-Edinburgh type large-volume press for simultaneous measurements of X-ray diffraction, electrical resistance, Seebeck coefficient and relative changes in the thermal conductance at high pressures has been developed. The feasibility of performingin situmeasurements of the Seebeck coefficient and thermal measurements is demonstrated by observing well known solid–solid phase transitions of bismuth (Bi) up to 3 GPa and 450 K. A reversible polarity flip has been observed in the Seebeck coefficient across the Bi-I to Bi-II phase boundary. Also, successful Seebeck coefficient measurements have been performed for the classical high-temperature thermoelectric material PbTe under high pressure and temperature conditions. In addition, the relative change in the thermal conductivity was measured and a relative change in ZT, the dimensionless figure of merit, is described. This new capability enables pressure-induced structural changes to be directly correlated to electrical and thermal properties.

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 Low Temperature Studies on 1-2-2 Iron-based Superconductors Using Designer Diamond Cells

2013 ◽  
Vol 1582 ◽  
Author(s):  
Walter O. Uhoya ◽  
Georgiy M. Tsoi ◽  
Yogesh K. Vohra ◽  
Jonathan, E. Mitchell ◽  
Athena Safa-Sefat ◽  
...  
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
High Pressures ◽  
Density Wave ◽  
Spin Density Wave ◽  
Superconducting Transition ◽  
X Ray Diffraction ◽  
Iron Based Superconductors ◽  
Diamond Anvil ◽  
Iron Based

ABSTRACTHigh pressure low temperature electrical resistance measurements were carried out on a series of 122 iron-based superconductors using a designer diamond anvil cell. These studies were complemented by image plate x-ray diffraction measurements under high pressures and low temperatures at beamline 16-BM-D, HPCAT, Advanced Photon Source. A common feature of the 1-2-2 iron-based materials is the observation of anomalous compressibility effects under pressure and a Tetragonal (T) to Collapsed Tetragonal (CT) phase transition under high pressures. Specific studies on antiferromagnetic spin-density-wave Ba0.5Sr0.5Fe2As2 and Ba(Fe0.9Ru0.1)2As2 samples are presented to 10 K and 41 GPa. The collapsed tetragonal phase was observed at a pressure of 14 GPa in Ba0.5Sr0.5Fe2As2 at ambient temperature. The highest superconducting transition temperature in Ba0.5Sr0.5Fe2As2 was observed to be at 32 K at a pressure of 4.7 GPa. The superconductivity was observed to be suppressed on transformation to the CT phase in 122 materials.

scholarly journals Pressure-induced phase transition of La2Zr2O7 and La0.5Gd1.5Zr2O7 pyrochlore

RSC Advances ◽  
2019 ◽  
Vol 9 (33) ◽  
pp. 18954-18962 ◽  
Author(s):  
Jingjing Niu ◽  
Xiang Wu ◽  
Haibin Zhang ◽  
Shan Qin
Keyword(s):  
Phase Transition ◽  
Raman Spectroscopy ◽  
High Pressure ◽  
Diamond Anvil Cell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diamond Anvil

In situ high-pressure experiments on La2Zr2O7 and La0.5Gd1.5Zr2O7 have been carried out at up to approximately 40 GPa using synchrotron X-ray diffraction and Raman spectroscopy combined with a diamond anvil cell technique.

scholarly journals The novel high-pressure/high-temperature compound Co12P7 determined from synchrotron data

2020 ◽  
Vol 76 (10) ◽  
pp. 1665-1668
Author(s):  
Claire Zurkowski ◽  
Barbara Lavina ◽  
Stella Chariton ◽  
Sergey Tkachev ◽  
Vitali Prakapenka ◽  
...  
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
The Novel ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Group Type ◽  
Peak Broadening ◽  
High Pressure High Temperature ◽  
Diamond Anvil ◽  
Laser Heated

The structural properties of cobalt phosphides were investigated at high pressures and temperatures to better understand the behavior of metal-rich phosphides in Earth and planetary interiors. Using single-crystal X-ray diffraction synchrotron data and a laser-heated diamond anvil cell, we discovered a new high pressure–temperature (HP–HT) cobalt phosphide, Co12P7, dodecacobalt heptaphosphide, synthesized at 27 GPa and 1740 K, and at 48 GPa and 1790 K. Co12P7 adopts a structure initially proposed for Cr12P7 (space-group type P\overline{6}, Z =1), consisting of chains of edge-sharing CoP5 square pyramids and chains of corner-sharing CoP4 tetrahedra. This arrangement leaves space for trigonal–prismatic channels running parallel to the c axis. Coupled disordering of metal and phosphorus atoms has been observed in this structure for related M 12P7 (M = Cr, V) compounds, but all Co and P sites are ordered in Co12P7. All atomic sites in this crystal structure are situated on special positions. Upon decompression to ambient conditions, peak broadening and loss of reflections at high angles was observed, suggesting phase instability.

Sign in / Sign up

Export Citation Format

Share Document