A new high-pressure deformation apparatus D111-type apparatus, which is a larger version of the deformation T-Cup, was recently installed on a synchrotron beamline NE7A at PF-AR, KEK, Tsukuba, Japan. In this apparatus, well-controlled deformation experiments can be conducted up to ～30 GPa by driving two opposed second-stage anvils in the Kawai-type multi-anvil assembly. High-pressure and high-temperature deformation experiments with quantitative stress and strain measurements have been carried out using the D111-type apparatus in conjunction with synchrotron radiation. Some studies have been conducted to investigate deep Earth rheology including rheology of hcp iron, rheology of bridgmanite and post-spinel, and olivine-ringwoodite phase transformation under deformation.
Minerals and rocks exhibit various isotope compositions depending on their origins and histories. In interpreting their isotopic variations, the equilibrium isotope fractionation factor is a key because it depends on the environment parameters such as temperature. Recent studies have shown that the effect of pressure on the isotope fractionation, which was considered negligible compared to temperature, is significant under the conditions of the Earth's interior. In this article we review recent advances in experimental studies to determine the isotope fractionation of iron and hydrogen at high pressure over several GPa, discussing their issues and future perspectives.
Water content in the Earth's deep interior is still controversial. In this article, recent experimental studies on hydrous phases, which play an important role in the transportation of water into the deep mantle, were reviewed. In-situ X-ray diffraction measurements combined with multi-anvil apparatus and laser-heated diamond anvil cell techniques clarified phase transitions and solid solutions of hydrous phases over a wide composition range in the ternary MgSiO4H2-AlOOH-FeOOH system under pressures. Based on these results, deep water transportation to the deep lower mantle are discussed.
In this article, recent progress on our first-principles calculations of lattice thermal conductivities of lower mantle minerals is reviewed. Effective thermal conductivity at the deepest mantle is modeled based on the compositional average. Heat flux from the core to mantle is then quantitatively estimated.
To constrain the core compositions of terrestrial planets, sound velocity and density of liquid Fe-Ni-S and Fe-Ni-Si alloys were measured up to 14 GPa. Addition of S reduces the P-wave velocity and bulk modulus of liquid Fe-Ni while addition of Si rises the P-wave velocity and does not affect on the bulk modulus in the present pressure range. Based on the obtained elastic properties of liquid Fe-Ni-S and Fe-Ni-Si, the compositions of planetary cores are estimated by matching the planetary geodesy data to 3-7 wt%S or 7-14 wt%Si for Mercury and 30-34 wt%S or 28-33 wt%Si for Mars.
In this article, history and developments of high-pressure apparatuses and the High Pressure Conference of Japan, as well as The Japan Society of High-Pressure Science and Technology, are reviewed. In Japan, many new large-volume high-pressure apparatuses are invented in 1970's and further developed. Use of the diamond-anvil apparatus were rather delayed but finally very good system was constructed and succeeded to get world leading results. All these developments were made possible through the good communications and collaborations of high-pressure community in Japan.
Current status and activities of organizations relevant to high-pressure science and technology, including HP-GRC, EHPRG, and ACHPR, in the world have been reviewed in the light of the author's personal experience, with some emphasis on those in the Asia region. The roles of AIRAPT and possible contributions of JSHPST to this international association have also been discussed.
Recent progress in theoretical mineral physics based on the ab initio quantum mechanical computation method has been dramatic in conjunction with the advancement of computer technologies. It is now possible to predict stability and several physical properties of complex minerals quantitatively not only at high pressures but also at high temperatures with uncertainties that are comparable to or even smaller than those attached in experimental data. Our present challenges include calculations of high-P,T elasticity to constrain the lower mantle mineralogy, transport properties such as lattice thermal conductivity, and further extensions to terapascal phase equilibria of Earth materials for studying planetary interiors.
The Kawai-type multi-anvil press (KMAP) is a widely used high-pressure apparatus especially in the field of solid geophysics. Because of its large volume and stable pressure-temperature field in a sample, the KMAP provides reliable results especially on phase stability. However, further development of KMAP has been needed to solve open questions on the Earth's mantle structure and dynamics. We have developed KMAP techniques and applied them to phase relations experiments of mantle-related minerals and rocks up to the uppermost lower mantle conditions and bridgmanite defect chemistry and crystal chemistry up to the mid-mantle conditions.