Viscosity of silicate melts in CaMgSi2O6–NaAlSi2O6 system at high pressure     

Akio Suzuki  Eiji Ohtani  Hidenori Terasaki  Ken-ichi Funakoshi 《Physics and Chemistry of Minerals》2005,32(2):140-145

In situ X-ray viscometry of the silicate melts was carried out at high pressure and at high temperature. The viscosity of the silicate melts in the diopside(Di)–jadeite(Jd) system was determined in the pressure range from 1.88 GPa to 7.9 GPa and in the temperature range from 2,003 K to 2,173 K. The viscosity of the Di 25%–Jd 75% melt decreases continuously to 5.0 GPa, whereas the viscosity of the Di 50%–Jd 50% melt increases over 3.5 GPa. The viscosity of the Di50%–Jd 50% melt reaches a minimum around 3.5 GPa. Since the amounts of silicon in the two melts are the same, the difference in the pressure dependence of the viscosity may be controlled by another network-forming element, i.e., aluminum. The difference in the pressure dependence of the viscosities in the melts with two intermediate compositions in the Di–Jd system is estimated to be due to the difference in the melt structures at high pressures and high temperatures.  相似文献   

Fe–Mg partitioning between post-perovskite and ferropericlase in the lowermost mantle     

Takeshi Sakai  Eiji Ohtani  Hidenori Terasaki  Masaaki Miyahara  Masahiko Nishijima  Naohisa Hirao  Yasuo Ohishi  Nagayoshi Sata 《Physics and Chemistry of Minerals》2010,37(7):487-496

Fe–Mg partitioning between post-perovskite and ferropericlase has been studied using a laser-heated diamond anvil cell at pressures up to 154 GPa and 2,010 K which corresponds to the conditions in the lowermost mantle. The composition of the phases in the recovered samples was determined using analytical transmission electron microscopy. Our results reveal that the Fe–Mg partition coefficient between post-perovskite and ferropericlase (K _D^PPv/Fp) increases with decreasing bulk iron content. The compositional dependence of K _D^PPv/Fp on the bulk iron content explains the inconsistency in previous studies, and the effect of the bulk iron content is the most dominant factor compared to other factors, such as temperature and aluminum content. Iron prefers ferropericlase compared to post-perovskite over a wide compositional range, whereas the iron content of post-perovskite (X _Fe^PPv, the mole fraction) does not exceed a value of 0.10. The iron-rich ferropericlase phase may have significant influence on the physical properties, such as the seismic velocity and electrical conductivity at the core–mantle boundary region.  相似文献