scholarly journals First-principles calculations of properties of orthorhombic iron carbideFe7C3at the Earth's core conditions

2015 ◽  
Vol 91 (21) ◽  
Author(s):  
Zamaan Raza ◽  
Nina Shulumba ◽  
Nuala M. Caffrey ◽  
Leonid Dubrovinsky ◽  
Igor A. Abrikosov
1997 ◽  
Vol 106 ◽  
pp. 205-218 ◽  
Author(s):  
Lidunka Vočadlo ◽  
Gilles A. de Wijs ◽  
Georg Kresse ◽  
Mike Gillan ◽  
Geoffrey D. Price

1998 ◽  
Vol 58 (13) ◽  
pp. 8248-8256 ◽  
Author(s):  
Dario Alfè ◽  
Michael J. Gillan

2003 ◽  
Vol 67 (1) ◽  
pp. 113-123 ◽  
Author(s):  
D. Alfé ◽  
M. J. Gillan ◽  
G. D. Price

AbstractWe summarize the main ideas used to determine the thermodynamic properties of pure systems and binary alloys from first principles calculations. These are based on the ab initio calculations of free energies. As an application we present the study of iron and iron alloys under Earth,s core conditions. In particular, we report the whole melting curve of iron under these conditions, and we put constraints on the composition of the core. We found that iron melts at 6350士600 K at the pressure corresponding to the boundary between the solid inner core and the liquid outer core (ICB). We show that the core could not have been formed from a binary mixture of Fe with S, Si or O and we propose a ternary or quaternary mixture with 8—10% of S/Si in both liquid and solid and an additional ~8% of oxygen in the liquid. Based on this proposed composition we calculate the shift of melting temperature with respect to the melting temperature of pure Fe of ~—700 K, so that our best estimate for the temperature of the Earth's core at ICB is 5650±600 K.


RSC Advances ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 3577-3581 ◽  
Author(s):  
Nursultan Sagatov ◽  
Pavel N. Gavryushkin ◽  
Talgat M. Inerbaev ◽  
Konstantin D. Litasov

We carried out ab initio calculations on the crystal structure prediction and determination of P–T diagrams within the quasi-harmonic approximation for Fe7N3 and Fe7C3.


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