TY - JOUR
T1 - Quasi-hydrostatic compression of magnesium oxide to 52 GPa
T2 - Implications for the pressure-volume-temperature equation of state
AU - Speziale, Sergio
AU - Zha, Chang Sheng
AU - Duffy, Thomas S.
AU - Hemley, Russell J.
AU - Mao, Ho Kwang
N1 - Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2001
Y1 - 2001
N2 - Room temperature static compression of MgO (periclase) was performed under nearly hydrostatic conditions using energy dispersive synchrotron X-ray diffraction in a diamond anvil cell with methanol-ethanol (to 10 GPa) or helium (to 52 GPa) as a pressuretransmitting medium. Highly precise cell parameters were determined with an average relative standard deviation = 0.0003 over all the experimental pressure range. Fixing the bulk modulus KOT= 160.2 GPa, a fit of the data to the third-order BirchMurnaghan equation of state yields: V0 = 74.71 ± 0.01 Å3,(∂K0T/∂P)r=3.99±0.01. Afit of different P-V-T datasets, ranging to 53 GPa and 2500 K, to a Birch-Murnaghan-Debye thermal equation of state constrained the Grüneisen parameter γ0 = 1.49 ± 0.03, but not its volume dependence q, which was constrained to 1.65 ± 0.4 by thermodynamic theory. A model based on a constant value of q cannot explain the ultrahigh pressure (P = 174-203 GPa) shock compression data. We developed a model in which q decreases with compression from 1.65 at 0.1 MPa to 0.01 at 200 GPa. This model, within the framework of the Mie-Gruneisen-Debye assumptions, satisfactorily describes the low-pressure static data = 0.4% to 53 GPa) and the high-pressure Hugoniot data (1% to 203 GPa). Average values of the thermal expansion coefficient α range between 14.1 ± 2.8 and 16.3 ± 2.7 × 10-6 K-1 P = 174-203 GPa. The pressure dependence of the melting temperature yields an initial pressure derivative ∂Tm/∂P = 98 K/GPa. Our analysis shows that it is possible to develop a simple model of the volume dependence of the Grüneisen parameter that can successfully describe the P-V-T equation of state of MgO from ambient conditions to 203 GPa and 3663 K.
AB - Room temperature static compression of MgO (periclase) was performed under nearly hydrostatic conditions using energy dispersive synchrotron X-ray diffraction in a diamond anvil cell with methanol-ethanol (to 10 GPa) or helium (to 52 GPa) as a pressuretransmitting medium. Highly precise cell parameters were determined with an average relative standard deviation = 0.0003 over all the experimental pressure range. Fixing the bulk modulus KOT= 160.2 GPa, a fit of the data to the third-order BirchMurnaghan equation of state yields: V0 = 74.71 ± 0.01 Å3,(∂K0T/∂P)r=3.99±0.01. Afit of different P-V-T datasets, ranging to 53 GPa and 2500 K, to a Birch-Murnaghan-Debye thermal equation of state constrained the Grüneisen parameter γ0 = 1.49 ± 0.03, but not its volume dependence q, which was constrained to 1.65 ± 0.4 by thermodynamic theory. A model based on a constant value of q cannot explain the ultrahigh pressure (P = 174-203 GPa) shock compression data. We developed a model in which q decreases with compression from 1.65 at 0.1 MPa to 0.01 at 200 GPa. This model, within the framework of the Mie-Gruneisen-Debye assumptions, satisfactorily describes the low-pressure static data = 0.4% to 53 GPa) and the high-pressure Hugoniot data (1% to 203 GPa). Average values of the thermal expansion coefficient α range between 14.1 ± 2.8 and 16.3 ± 2.7 × 10-6 K-1 P = 174-203 GPa. The pressure dependence of the melting temperature yields an initial pressure derivative ∂Tm/∂P = 98 K/GPa. Our analysis shows that it is possible to develop a simple model of the volume dependence of the Grüneisen parameter that can successfully describe the P-V-T equation of state of MgO from ambient conditions to 203 GPa and 3663 K.
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U2 - 10.1029/2000jb900318
DO - 10.1029/2000jb900318
M3 - Article
AN - SCOPUS:0035090377
VL - 106
SP - 515
EP - 528
JO - Journal of Geophysical Research
JF - Journal of Geophysical Research
SN - 0148-0227
IS - B1
ER -