Mineral physics studies using third-generation synchrotron facility

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We made applications of the third-generation synchrotron radiation at SPring-8 to various studies in mineral physics, using multianvil apparatus, such as observations of high-pressure phase transitions, determination of phase boundaries, detection of melting and determination of melting temperature under pressure, determination of the P-V-T relations of high pressure phases. Many successful experiments were conducted in this direction at the High Pressure Earth Science beamline at SPring-8, and abundant results have been obtained at pressures up to 25 GPa, and at temperatures to 2000℃. Moreover, attempts have been made to use sintered diamond anvils of relatively large dimensions (i.e. 14 mm edge length) for higher pressure generation. Pressures to 40 GPa, are now produced in multianvil apparatus using this technique, and the observations of phase transitions in QaMgSi2O6 diopside and MgAI2O4 spinel has been successfully made. In addition, new bulk moduli and thermal expansion data hav … More e been obtained for the high pressure phases of these minerals, i.e. MgSi03 perovskite, CaSiO3 perovskite, and MgA12O4 calcium ferrite, which provide important constraints on the density of the mantle and of subducting slabs in the upper part of the lower mantle.We made some collaborations with the researchers in SUNY at Stony Brook. We synthesized a hot-pressed specimen of modified-spinel type (Mg,Fe)2SiO4 using a multianvil apparatus which was brought to Stony Brook and used for ultrasonic measurements under high pressure. We obtained some signals for elastic wave velocities in this specimen at pressures to 13 GPa, which are currently being analyzed. Unfortunately, the simultaneous measurements of the elastic velocities and X-ray diffraction were not conducted, because of the limited beamtime at the synchrotron radiation facility. Nevertheless, we agreed to continue collaborative work in this direction for another two years with the financial support from JSPS as Japan-US collaboration program, which will certainly develop this new technique using the third-generation synchrotron radiation. Less