منابع مشابه
MgSiO3 postperovskite at D'' conditions.
The postperovskite transition in MgSiO(3) at conditions similar to those expected at the D'' discontinuity of Earth's lower mantle offers a paradigm for interpreting the properties of this region. Despite consistent experimental and theoretical predictions of this phase transformation, the complexity of the D'' region raises questions about its geophysical significance. Here we report the therm...
متن کاملVibrational and thermodynamic properties of MgSiO3 postperovskite
[1] Phonon dispersions and vibrational density of states of MgSiO3 postperovskite, the new high-pressure phase of MgSiO3 perovskite, are calculated as a function of pressure up to 180 GPa using density-functional perturbation theory. The calculated frequencies are then used to determine the thermal contribution to the Helmholtz free energy within the quasi-harmonic approximation. The equation o...
متن کاملPostperovskite phase equilibria in the MgSiO3-Al2O3 system.
We investigate high-P,T phase equilibria of the MgSiO(3)-Al(2)O(3) system by means of the density functional ab initio computation methods with multiconfiguration sampling. Being different from earlier studies based on the static substitution properties with no consideration of Rh(2)O(3)(II) phase, present calculations demonstrate that (i) dissolving Al(2)O(3) tends to decrease the postperovski...
متن کاملFate of MgSiO3 melts at core-mantle boundary conditions.
One key for understanding the stratification in the deep mantle lies in the determination of the density and structure of matter at high pressures, as well as the density contrast between solid and liquid silicate phases. Indeed, the density contrast is the main control on the entrainment or settlement of matter and is of fundamental importance for understanding the past and present dynamic beh...
متن کاملFerromagnesian postperovskite silicates in the D'' layer of the Earth.
Natural olivine with 12 mol % Fe(2)SiO(4) and synthetic orthopyroxenes with 20% and 40% FeSiO(3) were studied beyond the pressure-temperature conditions of the core-mantle boundary. All samples were found to convert entirely or partially into the CaIrO(3) postperovskite structure, which was recently reported for pure MgSiO(3). The incorporation of Fe greatly reduces the pressure needed for the ...
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ژورنال
عنوان ژورنال: Proceedings of the National Academy of Sciences
سال: 2006
ISSN: 0027-8424,1091-6490
DOI: 10.1073/pnas.0506879103