scholarly journals Study on the High-Pressure Behavior of Goethite up to 32 GPa Using X-Ray Diffraction, Raman, and Electrical Impedance Spectroscopy

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 99 ◽  
Author(s):  
Ruilian Tang ◽  
Jiuhua Chen ◽  
Qiaoshi Zeng ◽  
Yan Li ◽  
Xue Liang ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Impedance Spectroscopy ◽  
Electrical Impedance ◽  
High Pressures ◽  
Structural Phase ◽  
Second Order ◽  
Electrical Impedance Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray

Goethite is a major iron-bearing sedimentary mineral on Earth. In this study, we conducted in situ high-pressure x-ray diffraction, Raman, and electrical impedance spectroscopy measurements of goethite using a diamond anvil cell (DAC) at room temperature and high pressures up to 32 GPa. We observed feature changes in both the Raman spectra and electrical resistance at about 5 and 11 GPa. However, the x-ray diffraction patterns show no structural phase transition in the entire pressure range of the study. The derived pressure-volume (P-V) data show a smooth compression curve with no clear evidence of any second-order phase transition. Fitting the volumetric data to the second-order Birch–Murnaghan equation of state yields V0 = 138.9 ± 0.5 Å3 and K0 = 126 ± 5 GPa.

scholarly journals High-pressure X-ray diffraction and vibrational spectroscopy of polyethylene: Evidence for a structural phase transition

2020 ◽  
Vol 111 ◽  
pp. 103173
Author(s):  
D.M. Dattelbaum ◽  
E.D. Emmons ◽  
A.M. Covington ◽  
L.L. Stevens ◽  
N. Velisavljevic ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Vibrational Spectroscopy ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
X Ray

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.

X-ray diffraction investigations of CaF2 at high pressure

1992 ◽  
Vol 25 (5) ◽  
pp. 578-581 ◽  
Author(s):  
L. Gerward ◽  
J. S. Olsen ◽  
S. Steenstrup ◽  
M. Malinowski ◽  
S. Åsbrink ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Synchrotron Radiation ◽  
High Pressures ◽  
Low Pressure ◽  
Single Crystal Sample ◽  
X Ray Diffraction ◽  
Crystal Sample ◽  
X Ray ◽  
Pressure Phase

Synchrotron-radiation X-ray diffraction studies of CaF2 at high pressures have been performed on a powder sample up to 45 GPa and on a single-crystal sample up to 9.4 GPa. The bulk modulus of the low-pressure phase was determined to be B 0 = 87 (5) GPa. A phase transition was observed at about 9.5 GPa. The transition is accompanied by a volume contraction of 11%. The high-pressure phase is orthorhombic PbCl2 type (space group Pbnm). The sample only partially reverts to the low-pressure phase upon release of pressure.

scholarly journals High-pressure reversibility in a plastically flexible coordination polymer crystal

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiaojiao Liu ◽  
Adam A. L. Michalchuk ◽  
Biswajit Bhattacharya ◽  
Nobuhiro Yasuda ◽  
Franziska Emmerling ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Coordination Polymer ◽  
Structural Phase ◽  
Low Frequency ◽  
Hydrostatic Compression ◽  
X Ray Diffraction ◽  
X Ray ◽  
Three Point Bending ◽  
Mechanical Responses

AbstractSingle crystals which exhibit mechanical flexibility are promising materials for advanced technological applications. Before such materials can be used, a detailed understanding of the mechanisms of bending is needed. Using single crystal X-ray diffraction and microfocus Raman spectroscopy, we study in atomic detail the high-pressure response of the plastically flexible coordination polymer [Zn(μ-Cl)2(3,5-dichloropyridine)2]n (1). Contradictory to three-point bending, quasi-hydrostatic compression of (1) is completely reversible, even following compression to over 9 GPa. A structural phase transition is observed at ca. 5 GPa. DFT calculations show this transition to result from the pressure-induced softening of low-frequency vibrations. This phase transition is not observed during three-point-bending. Microfocus synchrotron X-ray diffraction revealed that bending yields significant mosaicity, as opposed to compression. Hence, our studies indicate of overall disparate mechanical responses of bulk flexibility and quasi-hydrostatic compression within the same crystal lattice. We suspect this to be a general feature of plastically bendable materials.

Magnetic Collapse and Insulator-Metal Transitions in Some 3D Metal Oxides Under High Pressures

2006 ◽  
Vol 987 ◽  
Author(s):  
Igor S. Lyubutin ◽  
Alexander G. Gavriliuk ◽  
Viktor Struzhkin
Keyword(s):  
High Pressure ◽  
Metal Oxides ◽  
High Pressures ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
Strong Electron ◽  
X Ray ◽  
Strong Electron Correlations ◽  
Synchrotron Radiation Techniques ◽  
Localized Magnetic Moment

AbstractIn the systems with strong electron correlations, many theories predict the high-pressure-induced dielectric-metal transition, which is followed by collapse of localized magnetic moment and structural phase transition. In this report, summary results of many last experiments on the influence of high pressure on the magnetic and crystal structure as well on the electronic and transport properties of 3d metal oxides is presented. Along with X-ray diffraction, optical absorption, Raman scattering and electroresistivity measurements, several synchrotron radiation techniques have also been applied to perform the high-pressure experiments with compound iron oxides having different crystal structures.

Local and long-range order in ferroelastic lead phosphate at high pressure

2004 ◽  
Vol 60 (1) ◽  
pp. 1-9 ◽  
Author(s):  
R. J. Angel ◽  
U. Bismayer ◽  
W. G. Marshall
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Single Crystal ◽  
Local Structure ◽  
High Pressures ◽  
X Ray Diffraction ◽  
Lead Phosphate ◽  
Pure Lead ◽  
Trigonal Symmetry ◽  
X Ray

Pure lead phosphate, Pb3(PO4)2, undergoes a phase transition from C2/c to R\bar 3m symmetry at a pressure of approximately 1.8 GPa and room temperature. Single-crystal X-ray diffraction measurements of the unit-cell parameters of a sample doped with 1.6% Ba2+ for the Pb2+ indicates that the doping reduces the transition pressure by approximately 0.1 GPa. The structural evolution of both samples through the phase transition has been determined by Rietveld refinement of neutron powder diffraction data collected to pressures of 6.3 and 3.3 GPa, respectively. There is no evidence for any significant change in the local structure at the phase transition at high pressures; the structure of the R\bar 3m phase at pressures just above the phase transition includes disordered positions for several atoms. The observation of diffuse scattering from the R\bar 3m phase at high pressure by single-crystal X-ray diffraction suggests that the disorder is static and arises from the presence of several orientations of the ordered microdomains of the monoclinic local structure. The macroscopic transition from monoclinic to trigonal symmetry therefore appears to correspond to the pressure at which the coherency strains between the locally monoclinic microdomains are sufficient to create a dimensionally trigonal lattice within which local displacements of atoms are still significant. A further pressure increase then decreases the magnitude of these displacements until at 3.5 GPa or higher they are not detectable by our current experimental probes, and the structure appears to have true local and global trigonal symmetry.

High pressure X-ray diffraction study on the structural phase transition in MnS2

Physica B+C ◽  
1986 ◽  
Vol 139-140 ◽  
pp. 305-307 ◽  
Author(s):  
T. Chattopadhyay ◽  
H.G. von Schnering ◽  
W.A. Grosshans
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Diffraction Study ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
X Ray

Phase Transition Study of CaB6 under High Pressure

2013 ◽  
Vol 705 ◽  
pp. 97-100
Author(s):  
Jia Wang ◽  
Gang Peng ◽  
Bao Jia Wu
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Conductivity Change ◽  
Electronic Phase ◽  
Transition Study ◽  
Abnormal Conductivity

Phase transition of CaB6 sample under high pressure was studied by in situ electrical conductivity measurements and synchrotron X-ray diffraction up to 26GPa. Three anomalies in conductivity change were found respectively at 3.7, 12.4 and 21.9GPa. X-ray diffraction reveals that CaB6 transforms from Pm3m to orthogonal structure at 12.32GPa and hence the abnormal conductivity change at 12.4GPa can be attributed to the structural phase transition. The other two anomalies were considered as pressure-induced electronic phase transition in the pressure range of our measurements.

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