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.

Laser-heating diamond anvil cell studies of simple molecular systems at high pressures and temperatures

2008 ◽  
Vol 69 (9) ◽  
pp. 2217-2222 ◽  
Author(s):  
Alexander F. Goncharov ◽  
Pierre Beck ◽  
Viktor V. Struzhkin ◽  
Russell J. Hemley ◽  
Jonathan C. Crowhurst
Keyword(s):  
Laser Heating ◽  
Diamond Anvil Cell ◽  
High Pressures ◽  
Molecular Systems ◽  
Diamond Anvil ◽  
High Pressures And Temperatures

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.

Decomposition of W(CO)6at high pressures and temperatures

2011 ◽  
Vol 44 (4) ◽  
pp. 820-830 ◽  
Author(s):  
Nadine Rademacher ◽  
Lkhamsuren Bayarjargal ◽  
Alexandra Friedrich ◽  
Wolfgang Morgenroth ◽  
Miguel Avalos-Borja ◽  
...  
Keyword(s):  
Particle Size ◽  
High Pressure ◽  
Tungsten Oxide ◽  
Diamond Anvil Cell ◽  
High Pressures ◽  
Function Analysis ◽  
Average Particle Size ◽  
Average Particle ◽  
Nanocrystalline Graphite ◽  
Diamond Anvil

The decomposition of hexacarbonyltungsten, W(CO)6, has been studied. The decomposition was induced by heating W(CO)6in an autoclave at 523 K and pressures up to 1.8 MPa, and by laser heating in a diamond anvil cell at pressures between 5 and 18 GPa. The products have been characterized using synchrotron X-ray diffraction, pair distribution function analysis, Raman spectroscopy and scanning electron microscopy. Decomposition in the autoclave at the lower pressures resulted in the formation of a metastable tungsten carbide, W2C, with an average particle size of 1–2 nm, and an unidentified nanocrystalline tungsten oxide and nanocrystalline graphite with average particle sizes of 1–2 and 11 nm, respectively. The existence of nanocrystalline graphite was deduced from micro-Raman spectra and the graphite particle size was extracted from the intensities of the Raman modes. The high-pressure decomposition products obtained in the diamond anvil cell are the monoclinic tungsten oxide phase WO2and the high-pressure phase W3O8(I). The approximate average size of the graphite particles formed here was 6–8 nm. The bulk modulus of W(CO)6isB0≃ 13 GPa.

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.

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.

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.

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