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| 2. |
- Belonoshko, Anatoly B., et al.
(författare)
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High-pressure melting of MgSiO3
- 2005
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 94:19
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Tidskriftsartikel (refereegranskat)abstract
- The melting curve of MgSiO3 perovskite has been determined by means of ab initio molecular dynamics complemented by effective pair potentials, and a new phenomenological model of melting. Using first principles ground state calculations, we find that the MgSiO3 perovskite phase transforms into post perovskite at pressures above 100 GPa, in agreement with recent theoretical and experimental studies. We find that the melting curve of MgSiO3, being very steep at pressures below 60 GPa, rapidly flattens on increasing pressure. The experimental controversy on the melting of the MgSiO3 perovskite at high pressures is resolved, confirming the data by Zerr and Boehler.
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| 3. |
- Belonoshko, Anatoly B., et al.
(författare)
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Molybdenum at High Pressure and Temperature : Melting from Another Solid Phase
- 2008
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Ingår i: Physical review letters / publ. by the American Physical Society. ; 100:13, s. 135701-
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Tidskriftsartikel (refereegranskat)abstract
- The Gibbs free energies of bcc and fcc Mo are calculated from first principles in the quasiharmonic approximation in the pressure range from 350 to 850 GPa at room temperatures up to 7500 K. It is found that Mo, stable in the bcc phase at low temperatures, has lower free energy in the fcc structure than in the bcc phase at elevated temperatures. Our density-functional-theory-based molecular dynamics simulations demonstrate that fcc melts at higher than bcc temperatures above 1.5 Mbar. Our calculated melting temperatures and bcc-fcc boundary are consistent with the Mo Hugoniot sound speed measurements. We find that melting occurs at temperatures significantly above the bcc-fcc boundary. This suggests an explanation of the recent diamond anvil cell experiments, which find a phase boundary in the vicinity of our extrapolated bcc-fcc boundary.
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| 4. |
- Cricchio, F., et al.
(författare)
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High-pressure melting of lead
- 2006
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 73:14
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Tidskriftsartikel (refereegranskat)abstract
- The melting curve of the hexagonal close-packed (hcp) phase of lead (Pb) has been determined over a wide pressure range using both ab initio molecular dynamics (AIMD) simulations and classical molecular dynamics (CMD) employing an effective pair potential. The AIMD simulations are based on a density functional theory (DFT) in the generalized gradient approximation (GGA). The Pb melting curve, constructed using a well-established theoretical scheme, is in excellent agreement with the AIMD results. Our calculated equation of state (EOS) of hcp Pb is in excellent agreement with experimental data up to 40 GPa. Our melting curve agrees very well with melting temperatures obtained in both shock-wave and diamond-anvil cell (DAC) experiments, but at higher pressures our curve lies between the two data sets.
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| 5. |
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| 6. |
- Mikhaylushkin, A. S., et al.
(författare)
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Mikhaylushkin et al. Reply
- 2008
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 101:4, s. 049602-
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Tidskriftsartikel (refereegranskat)
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| 7. |
- Wang, Y., et al.
(författare)
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First-principles calculations on MgO : Phonon theory versus mean-field potential approach
- 2006
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 100:2, s. 023533-
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Tidskriftsartikel (refereegranskat)abstract
- Various thermodynamic properties of MgO were studied using both ab initio phonon theory and the mean-field potential (MFP) approach. They include thermal pressure, thermal expansion, the 300 K equation of state, and the shock Hugoniot. It is found that the results of ab initio phonon theory and the MFP approach agree with each other, except that ab initio phonon theory gave a poor description of the thermal pressure when temperature became relatively high.
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| 8. |
- Belonoshko, Anatoly B., et al.
(författare)
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Melting of Fe and Fe0.9375Si0.0625 at Earth's core pressures studied using ab initio molecular dynamics
- 2009
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 79:22
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Tidskriftsartikel (refereegranskat)abstract
- The issue of melting of pure iron and iron alloyed with lighter elements at high pressure is critical to the physics of the Earth. The iron melting curve in the relevant pressure range between 3 and 4 Mbar is reasonably well established from the theoretical point of view. However, so far no one attempted a direct atomistic simulation of iron alloyed with light elements. We investigate here the impact of alloying the body-centered cubic (bcc) Fe with Si. We simulate melting of the bcc Fe and Fe0.9375Si0.0625 alloy by ab initio molecular dynamics. The addition of light elements to the hexagonal-close-packed (hcp) iron is known to depress its melting temperature (T-m). We obtain, in marked contrast, that alloying of bcc Fe with Si does not lead to T-m depression; on the contrary, the T-m slightly increases. This suggests that if Si is a typical impurity in the Earth's inner core, then the stable phase in the core is bcc rather than hcp.
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| 9. |
- Belonoshko, Anatoly B., et al.
(författare)
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Quenching of bcc-Fe from high to room temperature at high-pressure conditions : a molecular dynamics simulation
- 2009
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- The new high-temperature (T), high-pressure (P), body-centered cubic (bcc) phase of iron has probably already been synthesized in recent diamond anvil cell (DAC) experiments (Mikhaylushkin et al 2007 Phys. Rev. Lett. 99 165505). These DAC experiments on iron revealed that the high-PT phase on quenching transforms into a mixture of close-packed phases. Our molecular dynamics simulation and structural analysis allow us to provide a probable interpretation of the experiments. We show that quenching of the high-PT bcc phase simulated with the embedded-atom model also leads to the formation of the mixture of close-packed phases. Therefore, the assumption of the stability of the high-PT bcc iron phase is consistent with experimental observation.
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| 10. |
- Belonoshko, Anatoly, et al.
(författare)
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High-pressure melting of MgSiO3
- 2005
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Ingår i: Phys. Rev. Lett.. ; 94, s. 195701-
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Tidskriftsartikel (refereegranskat)
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