Thermal equation of state of CaFe2O4-type MgAl2O4

Autor: Yuichiro Sueda, Tetsuo Irifune, Takumi Kikegawa, Norimasa Nishiyama, T. Sanehira, Takehiko Yagi, Ken-ichi Funakoshi
Rok vydání: 2009
Předmět:
Zdroj: Physics of the Earth and Planetary Interiors. 174:78-85
ISSN: 0031-9201
Popis: In situ X-ray diffraction measurements of CaFe 2 O 4 -type MgAl 2 O 4 have been conducted at pressures up to 42 GPa and temperatures to 2400 K using Kawai-type multianvil apparatus with sintered diamond anvils. Additional measurements have also been conducted at pressures to 12 GPa using diamond anvil cell with helium as a pressure medium at room temperature, and at temperatures to 836 K at the ambient pressure using a high-temperature X-ray diffractometer. The analysis of room-temperature data yielded V 0 = 240.1(2) A 3 , K 0 = 205(6) GPa, and K ′ 0 = 4.1 ( 3 ) . A fit of the present data to high-temperature Birch–Murnaghan equation of state (EOS) yielded (∂ K 0 /∂ T ) P = −0.030(2) GPa/K and α 0 = a 0 + b 0 T with values of a 0 = 1.96(13) × 10 −5 K −1 and b 0 = 1.64(24) × 10 −8 K −2 . The present data set was also fitted to Mie–Gruneisen–Debye (MGD) EOS and we obtained γ 0 = 1.73(7), q = 2.03(37), and θ 0 = 1546(104) K. Density changes of MORB have been estimated using the newly obtained thermoelastic parameters, assuming that the Al-rich phase in this composition possesses the CaFe 2 O 4 -type structure under the lower mantle P , T conditions. The calculated densities along geotherms for the normal mantle and subducting cold slabs are both significantly higher than those of typical seismological models, confirming the conclusion of some recent results on MORB by laser-heated diamond anvil cell experiments.
Databáze: OpenAIRE
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