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 In situ Raman spectroscopy of cubic boron nitride to 90 GPa and 800 K

2014 ◽  
Vol 70 (a1) ◽  
pp. C760-C760
Author(s):  
Shigeaki Ono
Keyword(s):  
Raman Spectroscopy ◽  
High Pressure ◽  
Raman Spectrum ◽  
Boron Nitride ◽  
Raman Line ◽  
Pressure Dependence ◽  
Diamond Anvil Cell ◽  
Cubic Boron Nitride ◽  
In Situ Raman Spectroscopy ◽  
Diamond Anvil

Cubic boron nitride (c-BN) has some outstanding properties, such as hardness, chemical inertness, high temperature stability, and high thermal conductivity. The Raman spectrum of c-BN exhibits two intense lines at 1054 and 1305 cm-1 under ambient conditions, corresponding to the Brillouin zone center transverse optical (TO) and longitudinal optical (LO) modes, respectively. Previous studies have reported the pressure and temperature dependences of the frequency shift of the modes up to 40 GPa and 2300 K. The Raman line of the LO mode overlaps an intense Raman line of diamond at pressures higher than 3 GPa. Therefore, it is difficult to observe the LO line in high-pressure experiments using the diamond anvil cell. In contrast, previous studies proposed that the TO mode could be used as the pressure calibrant in diamond anvil cells under high pressure and temperature conditions. In this study, we used a diamond anvil cell high-pressure apparatus [1] combined with a Raman spectrometer system to investigate changes in the Raman line of c-BN. The use of a synchrotron radiation source made it possible to determine the precise pressure in the sample chamber. In this study, the temperature and pressure dependences of the Raman spectrum of the TO mode of cubic boron nitride were calibrated for applications to a Raman spectroscopy pressure sensor in optical cells to about 800 K and 90 GPa. A significant deviation from linearity of the pressure dependence is confirmed at pressures above 20 GPa. At ambient temperature, dv/dP slopes are 3.41 and 2.04 cm-1/GPa at 0 and 90 GPa, respectively. The pressure dependence does not significantly change with temperature, as determined from experiments conducted up to 800 K. At pressures above 90 GPa, the Raman spectrum of the TO mode cannot be observed because of an overlap of the signals of cubic boron nitride and diamond used as the anvils in the high-pressure cell.

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.

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.

The Fluorescence of Diamond and Raman Spectroscopy at High Pressures Using a New Design of Diamond Anvil Cell

1973 ◽  
Vol 27 (5) ◽  
pp. 377-381 ◽  
Author(s):  
D. M. Adams ◽  
S. J. Payne ◽  
K. Martin
Keyword(s):  
Raman Spectroscopy ◽  
Diamond Anvil Cell ◽  
High Pressures ◽  
Fluorescence Emission ◽  
Type I ◽  
High Pressure Cell ◽  
Scattering Geometry ◽  
Infrared And Raman Spectroscopy ◽  
Bond Stretching ◽  
Diamond Anvil

A new design of diamond anvil high pressure cell suitable for use in infrared and Raman spectroscopy is described. Its performance is demonstrated with particular reference to the pressure dependence of the infrared spectrum of K2PtCl6 and the Raman spectrum of W(CO)6. In contrast to earlier reports, in which forward scattering geometry was used, this design of cell is shown to be very suitable for Raman use in the 180° excitation mode. However, severe limitations are imposed by the fluorescence emission of diamond and of sapphire. Conditions under which the cell can be used for Raman work are summarized. New fluorescence and Raman features are reported for diamond. In particular, a band at 1730 cm−1 is characteristic of type I stones and may be due to C to N bond stretching at defect centers.

In situ Raman spectroscopic technique for high-pressure studies of mineral and fluid inclusions formation 

2021 ◽  
Author(s):  
Nadezda Chertkova ◽  
Anna Spivak ◽  
Egor Zakharchenko ◽  
Yuriy Litvin ◽  
Oleg Safonov ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Diamond Anvil Cell ◽  
High Pressures ◽  
Rapid Development ◽  
Spectroscopic Technique ◽  
Diamond Growth ◽  
Russian Science ◽  
Geological Processes ◽  
Diamond Anvil

<p>Rapid development of <em>in situ</em> experimental techniques provides researchers with new opportunities to model geological processes, which take place deep in the Earth’s interior. Raman spectroscopy is considered a powerful analytical tool for investigation of the samples subjected to high pressures in a diamond anvil cell, since in such experiments phase assemblages can be determined in real time using measured Raman spectra.</p><p>In this study, we describe experimental methods for <em>in situ</em> observation and spectroscopic analysis of fluids and minerals, which constitute environment for diamond growth, at the upper mantle pressure conditions. Experiments were conducted in the externally heated, “piston-cylinder” type diamond anvil cell at pressures exceeding 6 GPa and temperatures up to 600 degree C. Phase relationships and fluid speciation were monitored during experiments to reconstruct the environment and mechanism of inclusions formation. Compared to other analytical tools, commonly used in combination with diamond anvil cell apparatus, Raman spectroscopy offers several advantages, such as short sample preparation time, non-destructive characterization of the phases observed in the sample chamber and relatively short measurement time.</p><p>This work was supported by grant No. 20-77-00079 from the Russian Science Foundation.</p>

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.

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.

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