Effect of incorporation of iron and aluminum on the thermoelastic properties of magnesium silicate perovskite |
| |
Authors: | Norimasa Nishiyama Takehiko Yagi Shigeaki Ono Hirotada Gotou Tatsuhiko Harada Takumi Kikegawa |
| |
Institution: | (1) Institute for Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan;(2) Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba 305-0801, Japan;(3) GeoSoilEnviroCARS, The University of Chicago, Building 434A, 9700 South Cass Avenue, Argonne, IL 60439, USA;(4) Present address: Institute for Frontier Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, Yokosuka 237-0061, Japan |
| |
Abstract: | In situ X-ray diffraction measurements of Fe- and Al-bearing MgSiO3-rich perovskite (FeAl-Pv), which was synthesized from a natural orthopyroxene, were performed at pressures of 19–32 GPa and
temperatures of 300–1,500 K using a combination of a Kawai-type apparatus with eight sintered-diamond anvils and synchrotron
radiation. Two runs were performed using a high-pressure cell with two sample chambers, and both MgSiO3 perovskite (Mg-Pv) and FeAl-Pv were synthesized simultaneously in the same cell. Thus we were able to measure specific volumes
(V/V
0) of Mg-Pv and FeAl-Pv at the same P−T conditions. At all the measurement conditions, values of the specific volume of FeAl-Pv are consistent with those of Mg-Pv
within 2 Standard Deviation, strongly suggesting that effect of incorporation of iron and aluminum on the thermoelastic properties
of magnesium silicate perovskite is undetectable in this composition, pressure, and temperature range. Two additional runs
were performed using a high-pressure cell that has one sample chamber and unit-cell volumes of FeAl-Pv were measured at pressures
and temperatures up to 32 GPa and 1,500 K, respectively. All the unit-cell volume data of FeAl-Pv perovskite were fitted to
the high temperature Birch–Murnaghan equation of state and a complete set of thermoelastic parameters of this perovskite was
determined with an assumption of K′
300,0 = 4. The determined parameters are K
300,0 = 243(3) GPa, (∂K
T,0/∂T)
P
= −0.030(8) GPa/K, a
0 = 2.78(18) × 10−5 K−1, and b
0 = 0.88(28) × 10−8 K−2, where a
0 and b
0 are the coefficients of the following expression describing the zero-pressure thermal expansion: α
T,0 = a
0 + b
0
T. The equation-of-state parameters of FeAl-Pv are in good agreement with those of MgSiO3 perovskite at the conditions corresponding to the uppermost part of the lower mantle. |
| |
Keywords: | Mg-perovskite Incorporation of Fe and Al In-situ X-ray diffraction Equation of state Lower mantle |
本文献已被 SpringerLink 等数据库收录! |
|