Analysis of Infrared Spectra of Fluid Films in Simulated EHD Contacts

1975 ◽  
Vol 97 (2) ◽  
pp. 145-150 ◽  
Author(s):  
J. L. Lauer ◽  
M. E. Peterkin
Keyword(s):  
Liquid Glass ◽  
Diamond Anvil Cell ◽  
Structural Changes ◽  
Spectroscopic Method ◽  
Emission Spectra ◽  
Phase Changes ◽  
Fluid Films ◽  
Diamond Anvil ◽  
Transition Points ◽  
Infrared Methods

Interferometry has provided the sensitivity needed for the gathering, through suitable windows, of infrared absorption and emission spectra of excellent resolution (<1 cm−1) from sample volumes even as small as EHD contact regions. Thus the power of molecular vibrational spectroscopy can be used to determine phase changes and structural changes in fluids subjected to conditions prevailing in EHD contacts. In this paper, some of the infrared methods are illustrated by the description of preliminary work in which the cavity of a high-pressure diamond anvil cell was used for contact simulation. Reference is made to a fluorescence-spectroscopic method of pressure determination in the diamond cell, which is also helpful in locating liquid/glass transition points.

scholarly journals The Structure of Ferroselite, FeSe2, at Pressures up to 46 GPa and Temperatures down to 50 K: A Single-Crystal Micro-Diffraction Analysis

Crystals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 289 ◽  
Author(s):  
Barbara Lavina ◽  
Robert Downs ◽  
Stanislav Sinogeikin
Keyword(s):  
Single Crystal ◽  
Low Temperatures ◽  
Diamond Anvil Cell ◽  
Structural Changes ◽  
High Pressures ◽  
Structural Instability ◽  
Crystal Structure Analysis ◽  
Ambient Conditions ◽  
Diamond Anvil

We conducted an in situ crystal structure analysis of ferroselite at non-ambient conditions. The aim is to provide a solid ground to further the understanding of the properties of this material in a broad range of conditions. Ferroselite, marcasite-type FeSe2, was studied under high pressures up to 46 GPa and low temperatures, down to 50 K using single-crystal microdiffraction techniques. High pressures and low temperatures were generated using a diamond anvil cell and a cryostat respectively. We found no evidences of structural instability in the explored P-T space. The deformation of the orthorhombic lattice is slightly anisotropic. As expected, the compressibility of the Se-Se dumbbell, the longer bond in the structure, is larger than that of the Fe-Se bonds. There are two octahedral Fe-Se bonds, the short bond, with multiplicity two, is slightly more compressible than the long bond, with multiplicity four; as a consequence the octahedral tetragonal compression slightly increases under pressure. We also achieved a robust structural analysis of ferroselite at low temperature in the diamond anvil cell. Structural changes upon temperature decrease are small but qualitatively similar to those produced by pressure.

scholarly journals The Structure of Ferroselite, FeSe2, at Pressures Upto 46 GPa and Temperatures Down to 50 K: ASingle-Crystal Micro-Diffraction Analysis

2018 ◽  
Author(s):  
Barbara Lavina ◽  
Robert T Downs ◽  
Stanislav Sinogeikin
Keyword(s):  
Low Temperatures ◽  
Diamond Anvil Cell ◽  
Structural Changes ◽  
High Pressures ◽  
Structural Instability ◽  
Crystal Structure Analysis ◽  
Temperature Decrease ◽  
Ambient Conditions ◽  
Diamond Anvil

We conducted an in-situ crystal structure analysis of ferroselite at non-ambient conditions. The aim is to provide a solid ground to further the understanding of the properties of this material in a broad range of conditions. Ferroselite, marcasite-type FeSe2, was studied under high pressures up to 46 GPa and low temperatures, down to 50 K using single-crystal microdiffraction techniques. High pressure and low temperatures were generated using a diamond anvil cell and a cryostat. We found no evidences of structural instability in the explored P-T space. The deformation of the orthorhombic lattice is slightly anisotropic. As expected, the compressibility of the Se-Se dumbbell, the longer bond in the structure, is larger than that of the Fe-Se bonds. Less obvious is the behavior of the octahedral bonds, the shorter bond is the most compressible determining a small increase in the octahedron distortion with pressure. We also achieved a robust structural analysis of ferroselite at low temperature in the diamond anvil cell. Structural changes upon temperature decrease are small but qualitatively similar to those produced by pressure.

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.

Mechanochemical induced structural changes in sucrose using the rotational diamond anvil cell

2018 ◽  
Vol 123 (8) ◽  
pp. 085901 ◽  
Author(s):  
Jennifer A. Ciezak-Jenkins ◽  
Timothy A. Jenkins
Keyword(s):  
Diamond Anvil Cell ◽  
Structural Changes ◽  
Diamond Anvil

scholarly journals Bulk modulus of H2O across the ice VII–ice X transition measured by time-resolved x-ray diffraction in dynamic diamond anvil cell experiments

2021 ◽  
Vol 103 (6) ◽  
Author(s):  
A. S. J. Méndez ◽  
F. Trybel ◽  
R. J. Husband ◽  
G. Steinle-Neumann ◽  
H.-P. Liermann ◽  
...  
Keyword(s):  
Bulk Modulus ◽  
Diamond Anvil Cell ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Diamond Anvil

High temperature diamond anvil cell with the laser heating

1989 ◽  
Vol 1 (5-6) ◽  
pp. 337-340 ◽  
Author(s):  
M. I. Eremets ◽  
V. V. Struzhkin ◽  
I. A. Trojan
Keyword(s):  
High Temperature ◽  
Laser Heating ◽  
Diamond Anvil Cell ◽  
Diamond Anvil

scholarly journals Phase transitions beyond post-perovskite in NaMgF3 to 160 GPa

2019 ◽  
Vol 116 (39) ◽  
pp. 19324-19329 ◽  
Author(s):  
Rajkrishna Dutta ◽  
Eran Greenberg ◽  
Vitali B. Prakapenka ◽  
Thomas S. Duffy
Keyword(s):  
Phase Transitions ◽  
Diamond Anvil Cell ◽  
Extrasolar Planets ◽  
High Pressures ◽  
Model System ◽  
Similar Sequence ◽  
Deep Interior ◽  
Diamond Anvil ◽  
Binary Compounds ◽  
Pressure Phase

Neighborite, NaMgF3, is used as a model system for understanding phase transitions in ABX3 systems (e.g., MgSiO3) at high pressures. Here we report diamond anvil cell experiments that identify the following phases in NaMgF3 with compression to 162 GPa: NaMgF3 (perovskite) → NaMgF3 (post-perovskite) → NaMgF3 (Sb2S3-type) → NaF (B2-type) + NaMg2F5 (P21/c) → NaF (B2) + MgF2 (cotunnite-type). Our results demonstrate the existence of an Sb2S3-type post-post-perovskite ABX3 phase. We also experimentally demonstrate the formation of the P21/c AB2X5 phase which has been proposed theoretically to be a common high-pressure phase in ABX3 systems. Our study provides an experimental observation of the full sequence of phase transitions from perovskite to post-perovskite to post-post-perovskite followed by 2-stage breakdown to binary compounds. Notably, a similar sequence of transitions is predicted to occur in MgSiO3 at ultrahigh pressures, where it has implications for the mineralogy and dynamics in the deep interior of large, rocky extrasolar planets.

scholarly journals The thermal conductivity of the Earth's core and implications for its thermal and compositional evolution

2020 ◽  
Author(s):  
Kenji Ohta ◽  
Kei Hirose
Keyword(s):  
Thermal Conductivity ◽  
High Pressure ◽  
Thermal History ◽  
Diamond Anvil Cell ◽  
High Pressures ◽  
Iron Alloys ◽  
Compositional Evolution ◽  
The Earth ◽  
Diamond Anvil ◽  
High Pressures And Temperatures

Abstract Precise determinations of the thermal conductivity of iron alloys at high pressures and temperatures are essential for understanding the thermal history and dynamics of the metallic cores of the Earth. We review relevant high-pressure experiments using a diamond-anvil cell and discuss implications of high core conductivity for its thermal and compositional evolution.

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