scholarly journals First-principles anharmonic vibrational study of the structure of calcium silicate perovskite under lower mantle conditions

2019 ◽  
Vol 99 (6) ◽  
Author(s):  
Joseph C. A. Prentice ◽  
Ryo Maezono ◽  
R. J. Needs
Keyword(s):  
First Principles ◽  
Calcium Silicate ◽  
Lower Mantle ◽  
Vibrational Study ◽  
Calcium Silicate Perovskite

scholarly journals The Characterization, Stability, and Reactivity of Synthetic Calcium Silicate Surfaces from First Principles

2014 ◽  
Vol 118 (28) ◽  
pp. 15214-15219 ◽  
Author(s):  
E. Durgun ◽  
H. Manzano ◽  
P. V. Kumar ◽  
Jeffrey C. Grossman
Keyword(s):  
First Principles ◽  
Calcium Silicate

scholarly journals Structural dynamics of basaltic melt at mantle conditions with implications for magma oceans and superplumes

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Arnab Majumdar ◽  
Min Wu ◽  
Yuanming Pan ◽  
Toshiaki Iitaka ◽  
John S. Tse
Keyword(s):  
Transport Properties ◽  
Structural Dynamics ◽  
First Principles ◽  
Lower Mantle ◽  
Coordination Numbers ◽  
Atomic Interactions ◽  
Molecular Dynamics Calculations ◽  
Basaltic Melt ◽  
Magma Oceans ◽  
Structure Density

Abstract Transport properties like diffusivity and viscosity of melts dictated the evolution of the Earth’s early magma oceans. We report the structure, density, diffusivity, electrical conductivity and viscosity of a model basaltic (Ca11Mg7Al8Si22O74) melt from first-principles molecular dynamics calculations at temperatures of 2200 K (0 to 82 GPa) and 3000 K (40–70 GPa). A key finding is that, although the density and coordination numbers around Si and Al increase with pressure, the Si–O and Al–O bonds become more ionic and weaker. The temporal atomic interactions at high pressure are fluxional and fragile, making the atoms more mobile and reversing the trend in transport properties at pressures near 50 GPa. The reversed melt viscosity under lower mantle conditions allows new constraints on the timescales of the early Earth’s magma oceans and also provides the first tantalizing explanation for the horizontal deflections of superplumes at ~1000 km below the Earth’s surface.

scholarly journals The Effect of Pulsed Laser Heating on the Stability of Ferropericlase at High Pressures

Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 542
Author(s):  
Georgios Aprilis ◽  
Anna Pakhomova ◽  
Stella Chariton ◽  
Saiana Khandarkhaeva ◽  
Caterina Melai ◽  
...  
Keyword(s):  
High Pressure ◽  
Lower Mantle ◽  
Laser Heating ◽  
High Pressures ◽  
Pulsed Laser ◽  
Experimental Conditions ◽  
Lowermost Part ◽  
The Stability ◽  
Pulsed Laser Heating ◽  
Calcium Silicate Perovskite

It is widely accepted that the lower mantle consists of mainly three major minerals—ferropericlase, bridgmanite and calcium silicate perovskite. Ferropericlase ((Mg,Fe)O) is the second most abundant of the three, comprising approximately 16–20 wt% of the lower mantle. The stability of ferropericlase at conditions of the lowermost mantle has been highly investigated, with controversial results. Amongst other reasons, the experimental conditions during laser heating (such as duration and achieved temperature) have been suggested as a possible explanation for the discrepancy. In this study, we investigate the effect of pulsed laser heating on the stability of ferropericlase, with a geochemically relevant composition of Mg0.76Fe0.24O (Fp24) at pressure conditions corresponding to the upper part of the lower mantle and at a wide temperature range. We report on the decomposition of Fp24 with the formation of a high-pressure (Mg,Fe)3O4 phase with CaTi2O4-type structure, as well as the dissociation of Fp24 into Fe-rich and Mg-rich phases induced by pulsed laser heating. Our results provide further arguments that the chemical composition of the lower mantle is more complex than initially thought, and that the compositional inhomogeneity is not only a characteristic of the lowermost part, but includes depths as shallow as below the transition zone.

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