The Review of High Pressure Science and Technology

Reviews -Frontier of High-Pressure Earth Science-

Sintered Diamond and Research of the Earth's Interior

Eiji ITO, Atsushi KUBO

Article type: Review
Subject area: High Pressure Science and Technology
2002 Volume 12 Issue 2 Pages 104-111
Published: 2002
Released on J-STAGE: June 26, 2003

DOIhttps://njjn-jsjc-gov-cn-s-1416.res.gxlib.org.cn:443/rwt/1416/https/MSYXTLUQPJUB/10.4131/jshpreview.12.104

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The maximum attainable pressure in a Kawai-type of high-pressure apparatus (KHA) is limited to about 27 GPa when using tungsten carbide (WC) as the anvil material. Recently a remarkable innovation has been made for the KHA by adopting sintered diamond (SD) as the anvil material. So far pressures up to 50 GPa have been confirmed in SD anvil assemblies without any reduction of the specimen volume. Therefore, phase equilibrium and melting experiments of Earth materials have been extended to conditions deep into the lower mantle. The results will substantially advance our understanding of the structure of the lower mantle and the state of the Earth early in its history.

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Recent Advances in High Pressure High Temperature Experiments using a Laser Heated Diamond Anvil Cell and Synchrotron Radiation

Tadashi KONDO

Article type: Review
Subject area: High Pressure Science and Technology
2002 Volume 12 Issue 2 Pages 112-119
Published: 2002
Released on J-STAGE: June 26, 2003

DOIhttps://njjn-jsjc-gov-cn-s-1416.res.gxlib.org.cn:443/rwt/1416/https/MSYXTLUQPJUB/10.4131/jshpreview.12.112

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A laser heated diamond anvil cell (LHDAC) is a powerful tool to investigate the Earth's deep interior. Recent advances and problems of synchrotron experiments are reviewed in this paper. An on-line temperature and pressure measurement system was developed for effective laser heating experiments. High temperature reduction of iron bearing material was discussed also. The results of an in-situ powder X-ray diffraction experiment are shown for SiO₂ and (Mg, Fe)O. Stishovite transforms to a CaCl₂-structured phase at about 55 GPa and the phase was stable up to 80 GPa and 2000°C. A rhombohedral distortion of magnesiowüsutite was observed for (Mg, Fe)O. The positive phase boundary between rocksalt and the rhombohedral phase continues over 100 GPa.

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MD Simulation of Temperature-Pressure-Volume Equation of State for MgO

Masanori MATSUI

Article type: Review
Subject area: High Pressure Science and Technology
2002 Volume 12 Issue 2 Pages 120-125
Published: 2002
Released on J-STAGE: June 26, 2003

DOIhttps://njjn-jsjc-gov-cn-s-1416.res.gxlib.org.cn:443/rwt/1416/https/MSYXTLUQPJUB/10.4131/jshpreview.12.120

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Molecular dynamics (MD) simulation with a realistic and precise potential model is found to be very successful in accurately reproducing the observed molar volume and the measured elastic constants of MgO at ambient conditions, and their temperature and pressure dependencies over wide temperature and pressure ranges. We present the MD simulated temperature-pressure-volume equation of state for MgO as a reliable internal pressure calibration standard at high temperatures and high pressures.

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Mineral Chemistry of Al-bearing Materials in the Earth's Lower Mantle

Hiroshi KOJITANI, Nobuyoshi MIYAJIMA

Article type: Review
Subject area: High Pressure Science and Technology
2002 Volume 12 Issue 2 Pages 126-137
Published: 2002
Released on J-STAGE: June 26, 2003

DOIhttps://njjn-jsjc-gov-cn-s-1416.res.gxlib.org.cn:443/rwt/1416/https/MSYXTLUQPJUB/10.4131/jshpreview.12.126

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Recent high-pressure and high-temperature experiments strongly imply the possibility of non-stoichiometry for Al, Fe³⁺ containing MgSiO₃ perovskite and the related Al-phases. Therefore, the non-stoichiometric behavior of perovskites in the MgSiO₃-MgAlO_2.5 system and also in the multi-component system which are similar to natural mantle minerals and rocks was discussed by considering the trivalent cation substitution mechanism: 2^VI Si⁴⁺ ⇔ 2^VI (Al³⁺, Fe³⁺) + V_O^••. Since the behavior of Al coupled with iron in the MgSiO₃ perovskite is much more complicated because of the issue of fO₂ conditions, it is still under discussion. For dealing with the chemical behavior of Fe³⁺ in the perovskite, the electron energy-loss spectroscopy (EELS) in transmission electron microscopy (TEM) is becoming a powerful tool by which we can determine the Fe³⁺ / ΣFe ratio of coexisting phases separately on a nanometer order of resolution. It is expected that the EELS method combined with TEM techniques will be very useful to characterize synthetic high-pressure mantle minerals.

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Physical Properties of Molten Iron Alloys at High Pressures

Satoru URAKAWA, Hidenori TERASAKI

Article type: Review
Subject area: High Pressure Science and Technology
2002 Volume 12 Issue 2 Pages 138-144
Published: 2002
Released on J-STAGE: June 26, 2003

DOIhttps://njjn-jsjc-gov-cn-s-1416.res.gxlib.org.cn:443/rwt/1416/https/MSYXTLUQPJUB/10.4131/jshpreview.12.138

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In order to understand the formation, evolution and dynamic processes of the molten core of the terrestrial planets, knowledge of the physical properties, such as viscosity and density, of the molten iron alloy is required. Recent progress in the high-pressure technology combined with synchrotron radiation allows us to measure such properties at high-temperature and high-pressure. In this article, recent advances in the high-pressure research of molten iron alloys are reviewed.

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Infrared Microspectroscopy of OH in Minerals under High Temperature and High Pressure with High Temperature DAC

Keiji SHINODA

Article type: Review
Subject area: High Pressure Science and Technology
2002 Volume 12 Issue 2 Pages 145-152
Published: 2002
Released on J-STAGE: June 26, 2003

DOIhttps://njjn-jsjc-gov-cn-s-1416.res.gxlib.org.cn:443/rwt/1416/https/MSYXTLUQPJUB/10.4131/jshpreview.12.145

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A high temperature diamond anvil cell (HTDAC) was installed in an infrared (IR) microscope at BL43IR of the synchrotron radiation (SR) facility SPring8 to investigate the behavior of “water” in minerals. Since IRSR as an IR light source is more brilliant than a conventional IR source, the IRSR is useful for IR measurements under experimentally difficult conditions such as in a DAC study. In this text, IR microspectroscopy of BL43IR at SPring8, the HTDAC for IR study and the behavior of the proton in brucite (Mg(OH)₂) under high temperature and high pressure revealed by IR absorption spectra with IRSR and HTDAC are introduced.

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Reviews

Error Sources of Pressure Measurement in High-Pressure and High-Temperature X-ray Diffraction Studies Using Multi-Anvil Apparatus

Nobumasa FUNAMORI

Article type: Review
Subject area: High Pressure Science and Technology
2002 Volume 12 Issue 2 Pages 153-158
Published: 2002
Released on J-STAGE: June 26, 2003

DOIhttps://njjn-jsjc-gov-cn-s-1416.res.gxlib.org.cn:443/rwt/1416/https/MSYXTLUQPJUB/10.4131/jshpreview.12.153

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Accurate measurement of pressure is fundamental in high-pressure and high-temperature research. To make better measurements, it is important to identify error sources and their seriousness. Error sources in synchrotron X-ray-diffraction multi-anvil experiments, such as non-hydrostatic stresses, pressure effects on e.m.f. of thermocouples, uncertainties in pressure scales, etc. are reviewed.

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Structure, Dynamics, and Reaction of Supercritical Water

Nobuyuki MATUBAYASI

Article type: Review
Subject area: High Pressure Science and Technology
2002 Volume 12 Issue 2 Pages 159-166
Published: 2002
Released on J-STAGE: June 26, 2003

DOIhttps://njjn-jsjc-gov-cn-s-1416.res.gxlib.org.cn:443/rwt/1416/https/MSYXTLUQPJUB/10.4131/jshpreview.12.159

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The hydrogen bonding structure and dynamics of supercritical water is studied by means of high-temperature and high-pressure NMR. The proton chemical shift is measured over a wide range of thermodynamic conditions and is related to the number of hydrogen bonds in supercritical water with the help of computer simulations. It is found that the hydrogen bonding persists at supercritical temperatures and that the average number of hydrogen bonds is at least one in the supercritical densities. The spin-lattice relaxation time is further measured to determine the reorientational correlation time. It is shown that while the reorientational relaxation proceeds on the order of picosecond in ambient water, it does on the order of several tens of femtoseconds in supercritical water. The role of water in noncatalytic reactions in hydrothermal conditions is also examined by focusing on the dehydration of 1, 4-butanediol into tetrahydrofuran, which proceeds under the presence of a strong acid at ambient conditions. The water-induced and acid-catalyzed rate constants are separately determined, and water is proven to promote the reaction in its undissociated form.

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Techno-Series: Pressure Scale (2)

Ruby Pressure Scales and Hydrostaticity

Kenichi TAKEMURA

Article type: Review
Subject area: High Pressure Science and Technology
2002 Volume 12 Issue 2 Pages 167-170
Published: 2002
Released on J-STAGE: June 26, 2003

DOIhttps://njjn-jsjc-gov-cn-s-1416.res.gxlib.org.cn:443/rwt/1416/https/MSYXTLUQPJUB/10.4131/jshpreview.12.167

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The accuracy of pressure determination with ruby pressure scales is reviewed. Various problems associated with nonhydostatic stress conditions are discussed.

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