The Experts below are selected from a list of 20142 Experts worldwide ranked by ideXlab platform
Agnès Dewaele - One of the best experts on this subject based on the ideXlab platform.
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toroidal Diamond Anvil Cell for detailed measurements under extreme static pressures
Nature Communications, 2018Co-Authors: Agnès Dewaele, P. Loubeyre, Florent Occelli, Olivier Marie, M MezouarAbstract:Over the past 60 years, the Diamond Anvil Cell (DAC) has been developed into a widespread high static pressure device. The adaptation of laboratory and synchrotron analytical techniques to DAC enables a detailed exploration in the 100 GPa range. The strain of the Anvils under high load explains the 400 GPa limit of the conventional DAC. Here we show a toroidal shape for a Diamond Anvil tip that enables to extend the DAC use toward the terapascal pressure range. The toroidal-DAC keeps the assets for a complete, reproducible, and accurate characterization of materials, from solids to gases. Raman signal from the Diamond Anvil or X-ray signal from the rhenium gasket allow measurement of pressure. Here, the equations of state of gold, aluminum, and argon are measured with X-ray diffraction. The data are compared with recent measurements under similar conditions by two other approaches, the double-stage DAC and the dynamic ramp compression.
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Methodology for in situ synchrotron X-ray studies in the laser-heated Diamond Anvil Cell
High Pressure Research, 2017Co-Authors: Mohamed Mezouar, Innokenty Kantor, Agnès Dewaele, R. Giampaoli, Gaston Garbarino, G. Weck, Silvia Boccato, Volodymyr Svitlyk, Angelika Dorothea Rosa, R. TorchioAbstract:ABSTRACTA review of some important technical challenges related to in situ Diamond Anvil Cell laser heating experimentation at synchrotron X-ray sources is presented. The problem of potential chemical reactions between the sample and the pressure medium or the carbon from the Diamond Anvils is illustrated in the case of elemental tantalum. Preliminary results of a comparison between reflective and refractive optics for high temperature measurements in the laser-heated Diamond Anvil Cell are briefly discussed. Finally, the importance of the size and relative alignment of X-ray and laser beams for quantitative X-ray measurements is presented.
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high melting points of tantalum in a laser heated Diamond Anvil Cell
Physical Review Letters, 2010Co-Authors: Agnès Dewaele, M Mezouar, Nicolas Guignot, P. LoubeyreAbstract:In situ x-ray diffraction has been used to characterize the structural modifications of tantalum samples under intense laser irradiation, up to 135 GPa in a Diamond Anvil Cell. Melting data points are obtained that do not confirm the previously reported anomalously low melting curve. Two effects are identified that might alter the melting determination of refractory metals such as Ta under high static pressures. First, a strong chemical reactivity of Ta with the pressure transmitting media and with carbon diffusing out from the surface of the Anvils is observed. Second, pyrometry measurements can be distorted when the pressure medium melts. The strong divergence between ab initio calculations, shock measurements and static determination is resolved here and hence many theoretical interpretations are ruled out. Finally, the body-centered cubic phase is stable over the pressure-temperature range investigated.
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optical pressure sensors for high pressure high temperature studies in a Diamond Anvil Cell
High Pressure Research, 2007Co-Authors: Frederic Datchi, R. Letoullec, P. Loubeyre, Agnès Dewaele, Le Y Godec, B. CannyAbstract:We review the various optical pressure sensors that are suitable for high-pressure and high-temperature studies in a Diamond Anvil Cell. Two different kinds of sensors are considered: those based on the pressure shift of a fluorescence line (ruby, SrB4O7:Sm2+) and those based on the pressure shift of a Raman line (c-BN, Diamond). The calibration of those sensors are presented in detail, and discussion is made on their useful pressure and temperature ranges.
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Temperature and pressure distribution in the laser-heated Diamond–Anvil Cell
Review of Scientific Instruments, 1998Co-Authors: Agnès Dewaele, Guillaume Fiquet, Philippe GilletAbstract:Thermomechanical modeling of a sample assembly (sample plus pressure transmitting medium) in a laser-heated Diamond–Anvil Cell (LHDAC) is presented. Finite elements numerical calculation afforded to obtain the temperature distribution and the induced thermal pressure field, showing that a non-negligible pressure increase (called thermal pressure) occurs in the laser-heated zone. When argon is used as a pressure transmitting medium, thermal pressure can reach 20%–30% of the normal pressure measured in the cold zone. This modeling is supported by experimental studies. It is shown that discrepancies between Diamond–Anvil Cell and large volume press experiments on the coesite to stishovite transition are quantitatively explained by the thermal pressure effect. Moreover, thermal pressure also explains the anomalous low thermal expansion coefficient obtained by x-ray diffraction studies in LHDAC.
P. Loubeyre - One of the best experts on this subject based on the ideXlab platform.
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toroidal Diamond Anvil Cell for detailed measurements under extreme static pressures
Nature Communications, 2018Co-Authors: Agnès Dewaele, P. Loubeyre, Florent Occelli, Olivier Marie, M MezouarAbstract:Over the past 60 years, the Diamond Anvil Cell (DAC) has been developed into a widespread high static pressure device. The adaptation of laboratory and synchrotron analytical techniques to DAC enables a detailed exploration in the 100 GPa range. The strain of the Anvils under high load explains the 400 GPa limit of the conventional DAC. Here we show a toroidal shape for a Diamond Anvil tip that enables to extend the DAC use toward the terapascal pressure range. The toroidal-DAC keeps the assets for a complete, reproducible, and accurate characterization of materials, from solids to gases. Raman signal from the Diamond Anvil or X-ray signal from the rhenium gasket allow measurement of pressure. Here, the equations of state of gold, aluminum, and argon are measured with X-ray diffraction. The data are compared with recent measurements under similar conditions by two other approaches, the double-stage DAC and the dynamic ramp compression.
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high melting points of tantalum in a laser heated Diamond Anvil Cell
Physical Review Letters, 2010Co-Authors: Agnès Dewaele, M Mezouar, Nicolas Guignot, P. LoubeyreAbstract:In situ x-ray diffraction has been used to characterize the structural modifications of tantalum samples under intense laser irradiation, up to 135 GPa in a Diamond Anvil Cell. Melting data points are obtained that do not confirm the previously reported anomalously low melting curve. Two effects are identified that might alter the melting determination of refractory metals such as Ta under high static pressures. First, a strong chemical reactivity of Ta with the pressure transmitting media and with carbon diffusing out from the surface of the Anvils is observed. Second, pyrometry measurements can be distorted when the pressure medium melts. The strong divergence between ab initio calculations, shock measurements and static determination is resolved here and hence many theoretical interpretations are ruled out. Finally, the body-centered cubic phase is stable over the pressure-temperature range investigated.
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optical pressure sensors for high pressure high temperature studies in a Diamond Anvil Cell
High Pressure Research, 2007Co-Authors: Frederic Datchi, R. Letoullec, P. Loubeyre, Agnès Dewaele, Le Y Godec, B. CannyAbstract:We review the various optical pressure sensors that are suitable for high-pressure and high-temperature studies in a Diamond Anvil Cell. Two different kinds of sensors are considered: those based on the pressure shift of a fluorescence line (ruby, SrB4O7:Sm2+) and those based on the pressure shift of a Raman line (c-BN, Diamond). The calibration of those sensors are presented in detail, and discussion is made on their useful pressure and temperature ranges.
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The membrane Diamond Anvil Cell
High Pressure Research, 1990Co-Authors: R. Letoullec, J. P. Pinceaux, P. LoubeyreAbstract:Abstract A new design for a Diamond Anvil Cell is described. Its main characteristic is that the force on the piston is generated by pressurized helium. Two of its main qualities are illustrated on...
Martin Kunz - One of the best experts on this subject based on the ideXlab platform.
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thermal pressure in the laser heated Diamond Anvil Cell a quantitative study and implications for the density versus mineralogy correlation of the mantle
Journal of Geophysical Research, 2020Co-Authors: Quentin Williams, Connor Ethan Yen, Martin KunzAbstract:Thermal pressure is an inevitable thermodynamic consequence of heating a volumetrically constrained sample in the Diamond Anvil Cell. Its possible influences on experimentally determined density-mi...
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In situ laser heating and radial synchrotron X-ray diffraction in a Diamond Anvil Cell
Lawrence Berkeley National Laboratory, 2007Co-Authors: Martin Kunz, Wendel A. Caldwell, Lowell Miyagi, Hans-rudolf WenkAbstract:We report a first combination of Diamond Anvil Cell radial x-ray diffraction with in situ laser heating. The laser-heating setup of ALS beamline 12.2.2 was modified to allow one-sided heating of a sample in a Diamond Anvil Cell with an 80 W yttrium lithium fluoride laser while probing the sample with radial x-ray diffraction. The Diamond Anvil Cell is placed with its compressional axis vertical, and perpendicular to the beam. The laser beam is focused onto the sample from the top while the sample is probed with hard x-rays through an x-ray transparent boron-epoxy gasket. The temperature response of preferred orientation of (Fe,Mg)O is probed as a test experiment. Recrystallization was observed above 1500 K, accompanied by a decrease in stress.
Dion L. Heinz - One of the best experts on this subject based on the ideXlab platform.
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Thermal analysis in the laser-heated Diamond Anvil Cell
Experimental Techniques in Mineral and Rock Physics, 1993Co-Authors: Jeffrey S. Sweeney, Dion L. HeinzAbstract:A new technique actively controls thermal radiation and monitors sample properties during laser-heating in a Diamond Anvil Cell. The technique can be described as a qualitative application of thermal analysis. Discontinuities in temperature, laser power, visible thermal radiation, or in their derivatives as functions of time can be associated with the enthalpy of phase transitions (such as melting) or with changes in material properties (such as emissivity).
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Thermal pressure in the laser‐heated Diamond Anvil Cell
Geophysical Research Letters, 1990Co-Authors: Dion L. HeinzAbstract:Estimation of the thermal elastic effect is necessary for the calibration of the pressure and temperature conditions during laser-heated Diamond Anvil Cell experiments, since above 800K, the standard technique of using ruby florescence to measure pressure fails. Continuum calculations based upon the thermoelastic equations for an elastic medium were used to estimate the thermal pressure resulting from a radially symmetric temperature gradient in an elastic sphere with zero displacement on its surface. This calculation corresponds to the thermal pressure generated in a laser-heated Diamond Anvil Cell sample that is compressed without a pressure medium. This solution must fall between circumstances where the sample is held at constant pressure and where the sample is held at constant volume. It is shown here that the thermal pressure in an elastic medium with a Gaussian temperature gradient is approximately 40–60% of the thermodynamic value of the thermal pressure in a material raised to some constant temperature with the volume constrained to be constant. Even though the thermal pressure correction can be significant in terms of the total pressure that the sample experiences, these calculations indicate that the correction can be estimated to approximately 10%.
Takuo Okuchi - One of the best experts on this subject based on the ideXlab platform.
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A Peltier cooling Diamond Anvil Cell for low-temperature Raman spectroscopic measurements.
The Review of scientific instruments, 2016Co-Authors: Naoki Noguchi, Takuo OkuchiAbstract:A new cooling system using Peltier modules is presented for a low-temperature Diamond Anvil Cell instrument. This cooling system has many advantages: it is vibration-free, low-cost, and compact. It consists of double-stacked Peltier modules and heat sinks, where a cooled ethylene glycol-water mixture flows through a chiller. Current is applied to the Peltier modules by two programmable DC power supplies. Sample temperature can be controlled within the range 210-300 K with a precision of ±0.1 K via a Proportional-Integral-Differential (PID) control loop. A Raman spectroscopic study for the H2O ice VII-VIII transition is shown as an example of an application of the Peltier cooling Diamond Anvil Cell system.
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A new type of nonmagnetic Diamond Anvil Cell for nuclear magnetic resonance spectroscopy
Physics of the Earth and Planetary Interiors, 2004Co-Authors: Takuo OkuchiAbstract:Abstract Nuclear magnetic resonance (NMR) spectroscopy in the Diamond Anvil Cell (DAC) has the potential to be a powerful tool for high pressure science as suggested by previous works. NMR in the DAC at high temperatures and pressures would be useful for exploring materials under Earth and planetary conditions. As a step toward realizing this goal, we fabricated a new type of Diamond Anvil Cell from a nonmagnetic titanium alloy. The Cell was designed to generate a multiplied force within a compact dimension for use in superconducting magnets. Using a handmade rf probe and NMR system, a spin echo train was successfully detected for liquid H 2 O sample in the DAC at