Next Article in Journal
The Effect of Fly Ash Microspheres on the Pore Structure of Concrete
Next Article in Special Issue
The Bridgmanite–Akimotoite–Majorite Triple Point Determined in Large Volume Press and Laser-Heated Diamond Anvil Cell
Previous Article in Journal
Introduction to the Special Issue “Role of Magmatic Activity in the Generation of Ore Deposits”
Previous Article in Special Issue
First Principles Calculation of the Stability of Iron Bearing Carbonates at High Pressure Conditions
Open AccessArticle

Ab Initio Thermoelasticity of Liquid Iron-Nickel-Light Element Alloys

by Hiroki Ichikawa and Taku Tsuchiya *,†
Geodynamics Research Center, Ehime University, Matsuyama 790-8577, Japan
*
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Minerals 2020, 10(1), 59; https://doi.org/10.3390/min10010059
Received: 8 October 2019 / Revised: 8 January 2020 / Accepted: 8 January 2020 / Published: 9 January 2020
(This article belongs to the Special Issue Mineral Physics—In Memory of Orson Anderson)
The earth’s core is thought to be composed of Fe-Ni alloy including substantially large amounts of light elements. Although oxygen, silicon, carbon, nitrogen, sulfur, and hydrogen have been proposed as candidates for the light elements, little is known about the amount and the species so far, primarily because of the difficulties in measurements of liquid properties under the outer core pressure and temperature condition. Here, we carry out massive ab initio computations of liquid Fe-Ni-light element alloys with various compositions under the whole outer core P, T condition in order to quantitatively evaluate their thermoelasticity. Calculated results indicate that Si and S have larger effects on the density of liquid iron than O and H, but the seismological reference values of the outer core can be reproduced simultaneously by any light elements except for C. In order to place further constraints on the outer core chemistry, other information, in particular melting phase relations of iron light elements alloys at the inner core-outer core boundary, are necessary. The optimized best-fit compositions demonstrate that the major element composition of the bulk earth is expected to be CI chondritic for the Si-rich core with the pyrolytic mantle or for the Si-poor core and the (Mg,Fe)SiO3-dominant mantle. But the H-rich core likely causes a distinct Fe depletion for the bulk Earth composition.
Keywords: ab initio molecular dynamics; high-pressure thermoelasticity; outer core chemistry ab initio molecular dynamics; high-pressure thermoelasticity; outer core chemistry
MDPI and ACS Style

Ichikawa, H.; Tsuchiya, T. Ab Initio Thermoelasticity of Liquid Iron-Nickel-Light Element Alloys. Minerals 2020, 10, 59.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop