Infrared Absorption of Concentrated Aqueous NaClO4 Solutions to High Pressures and Temperatures

1981 ◽  
Vol 36 (11) ◽  
pp. 1169-1176 ◽  
Author(s):  
V. M. Valyashko ◽  
M. Buback ◽  
E. U. Franck

The infrared absorption of the O-D stretching fundamental of HDO in concentrated aqueous (HDO/H2O)NaClO4 solutions up to 20 mole% salt has been measured. The data for the wave-number of maximum absorption, ν̅(max), and for the integrated molar absorptivity B up to pressures and temperatures of 2800 bar and 250 °C, respectively, demonstrate the importance of non-hydrogen-bonded interactions in aqueous perchlorate solutions. A non-continuous dis­tribution of the states of water molecules is clearly evident from the experimental spectra. A band separation using three Gaussian components proves the close similarity between the high-pressure high-temperature vibrational O-D infrared spectra of aqueous perchlorate solutions and the O-D Raman spectra of water and aqueous solutions.Results of the band separation together with literature Raman data provide some evidence that a transition from “water-like” to “melt-like” behaviour occurs in a fairly narrow concentra­tion region between 10 and 15 mole% salt.

1983 ◽  
Vol 38 (5) ◽  
pp. 528-532 ◽  
Author(s):  
M. Buback ◽  
A. A. Harfoush

The near infrared absorption of pure n-heptane between 5000 cm-1 and 6500 cm-1 was measured up to 250 °C and to pressures of 2000 bar. The procedure for measuring vibrational intensities at high pressures and temperatures with a precision of better than ± 1% is described. The integrated “molar absorptivity of the combination mode va + vs of the methylene stretching fundamentals turns out to be independent of temperature and density. This offers important applications for high-pressure high-temperature thermodynamic and kinetic studies via quanti­tative near infrared spectroscopy.


1979 ◽  
Vol 34 (12) ◽  
pp. 1489-1495
Author(s):  
M. Buback ◽  
E. U. Franck ◽  
H. Lendlc

Abstract The infrared absorption of the ν1 and ν6 stretching fundamentals and of the ν2 CH2-bending mode in pure dichloromethane has been measured up to pressures and temperatures of 2 kbar and 200 °C, respectively. The optical high pressure cells were equipped with CaF2 single crystal windows. The applicability of this window material at high pressures and temperatures was investigated.With increasing density the wavenumbers of maximum absorption of ν1 and ν2 shift to lower and of ν6 to higher values. The integrated molar absorptivity of ν2 and ν6 increases with in-creasing density while it remains nearly constant for the ν1 vibration.The results obtained for the C-H modes clearly differ from those measured for O-H or N-H vibrations in polar materials. They are attributed to the action of repulsive forces in dense CH2Cl2.


Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 344
Author(s):  
William A. Bassett

The late Taro Takahashi earned a particularly well-deserved reputation for his research at Lamont Geological Observatory on carbon dioxide and its transfer between the atmosphere and the oceans. However, his accomplishments in Mineral Physics, the field embracing the high-pressure–high-temperature properties of materials, has received less attention in spite of his major contributions to this emerging field focused on the interiors of Earth and other planets. In 1963, I was thrilled when he was offered a faculty position in the Geology Department at the University of Rochester, where I had recently joined the faculty. Taro and I worked together for the next 10 years with our talented students exploring the blossoming field just becoming known as Mineral Physics, the name introduced by Orson Anderson and Ed Schreiber, who were also engaged in measuring physical properties at high pressures and temperatures. While their specialty was ultrasonic velocities in minerals subjected to high pressures and temperatures, ours was the determination of crystal structures, compressibilities, and densities of such minerals as iron, its alloys, and silicate minerals, especially those synthesized at high-pressure, such as silicates with the spinel structure. These were materials expected to be found in the Earth’s interior and could therefore provide background for the interpretation of geophysical observations.


2008 ◽  
Vol 403 ◽  
pp. 77-80 ◽  
Author(s):  
Peter Kroll

A combination of first-principle and thermochemical calculations is applied to compute the phase diagrams of rhenium-nitrogen and of ruthenium-nitrogen at elevated temperature and high pressure. We augment total energy calculations with our approach to treat the nitrogen fugacity at high pressures. We predict a sequential nitridation of Re at high-pressure/high-temperature conditions. At 3000 K, ReN will form from Re and nitrogen at about 32 GPa. A ReN2 with CoSb2-type structure may be achieved at pressures exceeding 50 GPa at this temperature. Marcasite-type RuN2 will be attainable at 3000 K at pressures above 30 GPa by reacting Ru with nitrogen.


1980 ◽  
Vol 35 (5) ◽  
pp. 549-555
Author(s):  
V. M. Valyashko ◽  
M. Buback ◽  
E. U. Franck

Abstract The infrared absorption of the O-D stretching fundamental of HDO in concentrated aqueous (HDO/H2O) LiCl solutions to a maximum of 40 mole percent salt has been measured. Data for the wavenumber of maximum absorption, ν̄(max), and for the integrated molar absorptivity B up to pressures and temperatures of 2800 bar and 350 °C, respectively, are reported and discussed. Toward high salt concentrations, the dependence of ν̄(max) on temperature and on LiCl concentration decreases. The wavenumber data indicate a transition from "water-like" to "melt-like" behaviour at about 12 to 15 mole percent LiCl.


2006 ◽  
Vol 61 (12) ◽  
pp. 1561-1565 ◽  
Author(s):  
Natalia Dubrovinskaia ◽  
Leonid Dubrovinsky ◽  
Nobuyoshi Miyajima ◽  
Falko Langenhorst ◽  
Wilson A. Crichton ◽  
...  

Bulk samples (with volumes up to ~ 7.5 mm3) of boron-doped diamonds (BDD) were synthesized by means of direct reaction between boron carbide and graphite in a multianvil apparatus at high pressures and high temperatures (HPHT). X-ray diffraction data revealed the presence in BDD of a very small amount of a highly boron-enriched phase (B50C2) and traces of the B13C2 used as an initial material. The absence of B50C2 in the product of treatment of pure B13C2 under the same HPHT conditions suggests that boron-rich carbides exsolute from diamond on quenching leading to boron depletion of the diamond matrix. These observations imply that boron solubility in diamond increases at high pressure and high temperature. This result may have important implications for the understanding of the mechanism of boron incorporation into diamond at HPHT synthesis and for the interpretation of the data on superconductivity of polycrystalline BDD.


Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 676 ◽  
Author(s):  
Raquel Chuliá-Jordán ◽  
David Santamaría-Pérez ◽  
Tomás Marqueño ◽  
Javier Ruiz-Fuertes ◽  
Dominik Daisenberger

The laser-heating diamond-anvil cell technique enables direct investigations of materials under high pressures and temperatures, usually confining the samples with high yield strength W and Re gaskets. This work presents experimental data that evidences the chemical reactivity between these refractory metals and CO2 or carbonates at temperatures above 1300 °Ϲ and pressures above 6 GPa. Metal oxides and diamond are identified as reaction products. Recommendations to minimize non-desired chemical reactions in high-pressure high-temperature experiments are given.


1979 ◽  
Vol 34 (3) ◽  
pp. 524 ◽  
Author(s):  
Jürgen Evers ◽  
Gilbert Oehlinger ◽  
Armin Weiss

Abstract After a high pressure -high temperature treatment of orthorhombic SrGe2 (BaSi2 type of structure) a trigonal polymorph (EuGe2 type of structure) is obtained: space group P3̄m 1; a - 410.4 pm, c - 516.5 pm; Z - 1; zGe = 0.406.


2007 ◽  
Vol 1040 ◽  
Author(s):  
Peter Kroll

AbstractWe apply our procedure of including nitrogen fugacity into thermochemical calculations to compute phase diagrams in the rhenium-nitrogen and ruthenium-nitrogen systems. The combination of first-principle and thermochemical calculations let us predict the sequential nitridation of Re at high-pressure/high-temperature conditions. At 3000 K, Re will react with nitrogen at about 32 GPa yielding ReN. Formation of ReN2 with CoSb2-type structure is predicted for pressures exceeding 50 GPa at this temperature. The recently proposed marcasite-type RuN2 will be attainable at 3000 K at pressures above 30 GPa from a mixture of Ru and RuN2.


2021 ◽  
Vol 73 (03) ◽  
pp. 55-55
Author(s):  
Robert Ziegler

For the past several months, the rig count in North America has been slowly but steadily improving and some pockets of deepwater operations are finally showing some activity, especially in Central and South America and Africa, where interesting discoveries continue. Arctic operations also are picking up, though not in North America, where a new administration in the US is bringing some uncertainty to upstream operations. Looking at leasing activity in 2020, however, the operators on federal land seem to have built up a backlog, so the immediate consequences of recent executive action seem not to be significant, though they do set an important precedent. More significant seems to be the opposition to pipelines, which are the most-efficient and safest way to transport any form of bulk material, be it gas, liquid, or slurry. Even if the most-stretched targets of an energy transition become reality, the need for pipeline transport will remain, and even increase, if the gas transported is biogas and hydrogen, where much larger volumes must be transported for the same calorific value of natural gas. In my tenure as a reviewer for JPT, I had refrained from a materials-focused special simply because high-pressure/high-temperature (HP/HT) conferences and sessions seem to be dominated by them and I wanted to demonstrate a wider spectrum of the challenges of HP/HT operations. With the energy transition leading to the possibility of free hydrogen being introduced into the energy system outside of established chemical feedstock installations (which are all low-pressure), this is a good time to remind our industry (and the outside world) that vast experience exists in the oil and gas industry on the interaction of hydrogen and metal (at very high pressures), a challenge that is still not completely understood and that is still a large cause of pressure-vessel failures (e.g., in refineries). Also, if carbon dioxide is intended to be captured and contained in metal vessels, another set of metallurgical challenges emerges. This Technology Focus looks at two papers from Asia, where these challenges were discovered and mitigated, and one paper from Gulf of Mexico deepwater operations. Many learnings can be taken from these papers, and extremely costly and safety-critical failures and loss of containment can be avoided. Addressing technical risk, thorough and detailed front-end engineering is a cost-effective and cost-saving activity, and this applies especially for front-end corrosion engineering and testing, as we have seen from several megaprojects in the past where this was not done to the extent finally understood to have been required. So, I invite you all to understand and embrace the fact that sound and competent engineering, as well as communicating learnings across functions and industries, is the key enabler for future success in our stressed industry, and to use our engineering brainpower and imagination to bring those HP/HT projects currently deemed too expensive to develop within the realm of the current oil-price environment.


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