(Mg,Fe)SiO3-Perovskite Stability and Lower Mantle Conditions
نویسندگان
چکیده
منابع مشابه
CaSiO3 perovskite at lower mantle pressures
[1] We investigate by first-principles the structural behavior of CaSiO3 perovskite up to lower mantle pressures. We confirm that the cubic perovskite modification is unstable at all pressures. The zero Kelvin structure is stabilized by SiO6 octahedral rotations that lower the symmetry to tetragonal, orthorhombic, rhombohedral, or to a cubic supercell. The resulting structures have comparable e...
متن کاملModeling the melting of multicomponent systems: the case of MgSiO3 perovskite under lower mantle conditions
Knowledge of the melting properties of materials, especially at extreme pressure conditions, represents a long-standing scientific challenge. For instance, there is currently considerable uncertainty over the melting temperatures of the high-pressure mantle mineral, bridgmanite (MgSiO3-perovskite), with current estimates of the melting T at the base of the mantle ranging from 4800 K to 8000 K. ...
متن کاملAb initio molecular dynamics study of CaSiO3 perovskite at P-T conditions of Earth’s lower mantle
First-principles molecular dynamics calculations were performed in order to investigate the structure and properties of what is thought to be the third most abundant phase in the Earth’s lower mantle, CaSiO3 perovskite. The commonly assumed cubic structure was found to be stable at high temperatures T 1000–2000 K and unstable at low temperatures at all pressures. For this structure we investiga...
متن کاملPhase transition in MgSiO3 perovskite in the earth’s lower mantle
A new polymorph of MgSiO3 more stable than the Pbnm-perovskite phase has been identified by first-principles computations. It has the CaIrO3 structure with Cmcm symmetry and consists of SiO3 layers intercalated by eightfoldcoordinated Mg ions. High-temperature calculations within the quasiharmonic approximation give a volume change of f 1.5% and a Clapeyron slope of f 7.5F 0.3 MPa/K at f 2750 K...
متن کاملElectronic spin state of iron in lower mantle perovskite.
The electronic spin state of iron in lower mantle perovskite is one of the fundamental parameters that governs the physics and chemistry of the most voluminous and massive shell in the Earth. We present experimental evidence for spin-pairing transition in aluminum-bearing silicate perovskite (Mg,Fe)(Si,Al)O(3) under the lower mantle pressures. Our results demonstrate that as pressure increases,...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Science
سال: 1999
ISSN: 0036-8075,1095-9203
DOI: 10.1126/science.285.5430.983a