scholarly journals Diamond and methane formation from the chemical decomposition of polyethylene at high pressures and temperatures

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
E. B. Watkins ◽  
R. C. Huber ◽  
C. M. Childs ◽  
A. Salamat ◽  
J. S. Pigott ◽  
...  
Keyword(s):  
High Pressures ◽  
Equations Of State ◽  
Spherical Particles ◽  
Radius Of Gyration ◽  
Methane Formation ◽  
Reaction Products ◽  
Chemical Decomposition ◽  
X Ray ◽  
Diamond Anvil ◽  
Laser Heated

AbstractPolyethylene (C2H4)n was compressed to pressures between 10 and 30 GPa in a diamond anvil cell (DAC) and laser heated above 2500 K for approximately one second. This resulted in the chemical decomposition of the polymer into carbon and hydrocarbon reaction products. After quenching to ambient temperature, the decomposition products were measured in the DAC at pressures ranging from ambient to 29 GPa using a combination of x-ray diffraction (XRD) and small angle x-ray scattering (SAXS). XRD identified cubic diamond and methane as the predominant product species with their pressure–volume relationships exhibiting strong correlations to the diamond and methane equations of state. Length scales associated with the diamond products, obtained from SAXS measurements, indicate the formation of nanodiamonds with a radius of gyration between 12 and 35 nm consistent with 32–90 nm diameter spherical particles. These results are in good agreement with the predicted product composition under thermodynamic and chemical equilibrium.

scholarly journals Synthesis of clathrate cerium superhydride CeH9 at 80-100 GPa with atomic hydrogen sublattice

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Nilesh P. Salke ◽  
M. Mahdi Davari Esfahani ◽  
Youjun Zhang ◽  
Ivan A. Kruglov ◽  
Jianshi Zhou ◽  
...  
Keyword(s):  
Atomic Hydrogen ◽  
High Pressures ◽  
Structure Stability ◽  
X Ray Diffraction ◽  
Detailed Chemistry ◽  
X Ray ◽  
3 Dimensional ◽  
Diamond Anvil ◽  
Laser Heated ◽  
Very High

Abstract Hydrogen-rich superhydrides are believed to be very promising high-Tc superconductors. Recent experiments discovered superhydrides at very high pressures, e.g. FeH5 at 130 GPa and LaH10 at 170 GPa. With the motivation of discovering new hydrogen-rich high-Tc superconductors at lowest possible pressure, here we report the prediction and experimental synthesis of cerium superhydride CeH9 at 80–100 GPa in the laser-heated diamond anvil cell coupled with synchrotron X-ray diffraction. Ab initio calculations were carried out to evaluate the detailed chemistry of the Ce-H system and to understand the structure, stability and superconductivity of CeH9. CeH9 crystallizes in a P63/mmc clathrate structure with a very dense 3-dimensional atomic hydrogen sublattice at 100 GPa. These findings shed a significant light on the search for superhydrides in close similarity with atomic hydrogen within a feasible pressure range. Discovery of superhydride CeH9 provides a practical platform to further investigate and understand conventional superconductivity in hydrogen rich superhydrides.

scholarly journals Experimental Issues in In-Situ Synchrotron X-Ray Diffraction at High Pressure and Temperature by Using a Laser-Heated Diamond-Anvil Cell

1997 ◽  
Vol 499 ◽  
Author(s):  
C. S. Yoo ◽  
H. Cynn ◽  
A. Campbell ◽  
J.-Z. Hu
Keyword(s):  
Diamond Anvil Cell ◽  
High Pressures ◽  
Thermal Gradients ◽  
X Ray Diffraction ◽  
High Pressure And Temperature ◽  
X Ray ◽  
Diamond Anvil ◽  
Integrated Technique ◽  
Laser Heated

ABSTRACTAn integrated technique of diamond-anvil cell, laser-heating and synchrotron x-ray diffraction technologies is capable of structural investigation of condensed matter in an extended region of high pressures and temperatures above 100 GPa and 3000 K. The feasibility of this technique to obtain reliable data, however, strongly depends on several experimental issues, including optical and x-ray setups, thermal gradients, pressure homogeneity, preferred orientation, and chemical reaction. In this paper, we discuss about these experimental issues together with future perspectives of this technique for obtaining accurate data.

In situ synchrotron X-ray diffraction with laser-heated diamond anvil cells study of Pt up to 95 GPa and 3150 K

RSC Advances ◽  
2015 ◽  
Vol 5 (19) ◽  
pp. 14603-14609 ◽  
Author(s):  
Xiaoli Huang ◽  
Fangfei Li ◽  
Qiang Zhou ◽  
Gang Wu ◽  
Yanping Huang ◽  
...  
Keyword(s):  
X Ray Diffraction ◽  
Diamond Anvil Cells ◽  
X Ray ◽  
Diamond Anvil ◽  
Laser Heated

In situ synchrotron X-ray diffraction with laser-heated diamond anvil cells study the EOS of Pt.

Construction of laser-heated diamond anvil cell system for in situ x-ray diffraction study at SPring-8

2001 ◽  
Vol 72 (2) ◽  
pp. 1289 ◽  
Author(s):  
Tetsu Watanuki ◽  
Osamu Shimomura ◽  
Takehiko Yagi ◽  
Tadashi Kondo ◽  
Maiko Isshiki
Keyword(s):  
Diffraction Study ◽  
Diamond Anvil Cell ◽  
Cell System ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diamond Anvil ◽  
Laser Heated

scholarly journals Melting of iron determined by X-ray absorption spectroscopy to 100 GPa

2015 ◽  
Vol 112 (39) ◽  
pp. 12042-12045 ◽  
Author(s):  
Giuliana Aquilanti ◽  
Angela Trapananti ◽  
Amol Karandikar ◽  
Innokenty Kantor ◽  
Carlo Marini ◽  
...  
Keyword(s):  
Melting Temperature ◽  
Absorption Spectroscopy ◽  
Inner Core ◽  
Solid Phase ◽  
Melting Curve ◽  
X Ray ◽  
Core Boundary ◽  
Diamond Anvil ◽  
Laser Heated ◽  
X Ray Absorption

Temperature, thermal history, and dynamics of Earth rely critically on the knowledge of the melting temperature of iron at the pressure conditions of the inner core boundary (ICB) where the geotherm crosses the melting curve. The literature on this subject is overwhelming, and no consensus has been reached, with a very large disagreement of the order of 2,000 K for the ICB temperature. Here we report new data on the melting temperature of iron in a laser-heated diamond anvil cell to 103 GPa obtained by X-ray absorption spectroscopy, a technique rarely used at such conditions. The modifications of the onset of the absorption spectra are used as a reliable melting criterion regardless of the solid phase from which the solid to liquid transition takes place. Our results show a melting temperature of iron in agreement with most previous studies up to 100 GPa, namely of 3,090 K at 103 GPa.

In situ synchrotron X-ray diffraction study of the formation of TaB2 from the elements in a laser heated diamond anvil cell

2010 ◽  
Vol 12 (12) ◽  
pp. 2059-2064 ◽  
Author(s):  
Björn Winkler ◽  
Erick A. Juarez-Arellano ◽  
Alexandra Friedrich ◽  
Lkhamsuren Bayarjargal ◽  
Florian Schröder ◽  
...  
Keyword(s):  
Diffraction Study ◽  
Diamond Anvil Cell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diamond Anvil ◽  
Laser Heated

High-pressure transformations of NbO2F

2000 ◽  
Vol 56 (2) ◽  
pp. 189-196 ◽  
Author(s):  
Stefan Carlson ◽  
Ann-Kristin Larsson ◽  
Franziska E. Rohrer
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
High Pressures ◽  
Ambient Pressure ◽  
Close Packing ◽  
Hexagonal Close Packing ◽  
Rietveld Refinements ◽  
X Ray ◽  
Anion Coordination ◽  
Diamond Anvil

The ReO3-type structure NbO2F, niobium dioxyfluoride, has been studied at high pressures using diamond anvil cells and synchrotron X-ray radiation. High-pressure powder diffraction measurements have been performed up to 40.1 GPa. A phase transition from the cubic (Pm3¯m) ambient pressure structure to a rhombohedral (R3¯c) structure at 0.47 GPa has been observed. Rietveld refinements at 1.38, 1.96, 3.20, 6.23, 9.00 and 10.5 GPa showed that the transition involves an a − a − a − tilting of the cation–anion coordination octahedra and a change of the anion–anion arrangement to approach hexagonal close packing. Compression and distortion of the Nb(O/F)6 octahedra is also revealed by the Rietveld refinements. At 17–18 GPa, the diffraction pattern disappears and the structure becomes X-ray amorphous.

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